1
INTRODUCTION ............................................................................................ 1-2
2
HEALTH, SAFETY, ENVIRONMENT AND SECURITY .................................. 2-1
3
PROJECT MANAGEMENT & CONTROL....................................................... 3-1
4
PLANNING & FORECASTING ....................................................................... 4-1
5
DEPOT DESIGN & ENGINEERING ............................................................... 5-2
6
HYDRANT DESIGN & ENGINEERING .......................................................... 6-1
7
GENERAL AVIATION..................................................................................... 7-1
8
MODULAR EQUIPMENT ............................................................................... 8-1
9
OTHER FACILITIES ENGINEERING ............................................................. 9-1
10
HAZARDOUS AREA CLASSIFICATION ...................................................... 10-1
11
ELECTRICAL ............................................................................................... 11-2
12
CONTROL.................................................................................................... 12-2
13
MATERIALS PROCUREMENT .................................................................... 13-1
14
CONSTRUCTION, INSPECTION AND TESTING ........................................ 14-1
15
COMMISSIONING........................................................................................ 15-1
16
VEHICLES.................................................................................................... 16-1
17
ENVIRONMENTAL....................................................................................... 17-2
18
DEMOLITION, ABANDONMENT & RESTORATION.................................... 18-1
A
DEFINITIONS AND ABBREVIATIONS...........................................................A-1
B
PROJECT CONTROL CHECKLIST................................................................B-1
A
TYPICAL STATEMENT OF REQUIREMENTS...............................................B-1
C
TYPICAL PROJECT STRATEGY...................................................................C-2
D
PROJECT CO-ORDINATION PROCEDURE .................................................D-2
E
INFORMATION GATHERING CHECKLIST....................................................E-2
F
INITIAL DESIGN STUDY................................................................................ F-2
G
TYPICAL DETAILED DRAWINGS................................................................. G-2
H
SOAK TESTING .............................................................................................H-1
I
MESH SCREENS FOR TANK VENTS ............................................................ I-1
J
CALCULATION OF PEAK HYDRANT FLOW RATE ...................................... J-2
K
CALCULATION OF TANK LEVEL ..................................................................K-1
L
EXAMPLES OF CONSTRUCTION SITE REPORTING DOCUMENTS .......... L-1
M
PRODUCT AND ENGINEERING DATA ........................................................ M-1
1
INTRODUCTION 1.1
PURPOSE .......................................................................................... 1-3
1.2
INTENDED USE OF THESE GUIDELINES ........................................ 1-3
1.3
NATIONAL AND LOCAL REQUIREMENTS........................................ 1-4
1.4
RELATED BP AND AIR BP PUBLICATIONS...................................... 1-4
1.5
AIR BP ENGINEERING STANDARDS................................................ 1-4
1.6
EXPLANATIONS AND EXAMPLES .................................................... 1-4
1.7
FEEDBACK AND FUTURE REVISIONS............................................. 1-4
1.8
USE OF LANGUAGE .......................................................................... 1-4
1.9
DEFINITIONS AND ABBREVIATIONS ............................................... 1-5
1.10
UNITS ................................................................................................. 1-5
1.11
DISTRIBUTION................................................................................... 1-5
1.12
COPYRIGHT....................................................................................... 1-5
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1.1
PURPOSE This Air BP Engineering Guide ('AEG') replaces the Air BP Aviation Engineering Practice ('AEP') last issued in 1975. The purpose of AEG is to provide guidance on the planning, design, construction and commissioning of safe, efficient and cost effective airfield aviation fuel facilities for civil use. The guidance given in AEG is based on experience gained since 1926 of the design, construction and operation of many aviation fuel facilities around the world. It therefore provides a sound basis for similar projects in the future. In general the guidance meets or exceeds the requirements for jointly owned/operated facilities given in the Guidelines for Aviation Fuel Quality Control and Operating Procedures for: •
Jointly Operated Supply & Distribution Facilities
•
Joint Airport Depots
•
Joint Into-Plane Fuelling Services.
It is not intended to preclude the use of alternative designs, or construction methods, where these can be proven to provide equivalent standards of safety and product quality, but confirmation should be sought from Air BP Centre Technical Branch, before such changes are implemented. This may need to be in the form of a waiver in accordance with the procedure given in ADM 30. AEG is not intended to be directly applicable to ‘off-airport’ projects in the supply chain, but the content may be useful when considering aviation fuel related issues. Key Considerations: AEG is a guide, not a specification. The designer is responsible for the end-product. Queries can be referred to Air BP Centre Engineering for advice. AEG is intended for Air BP internal use and to aid the briefing of external consultants. Use BP Group and Air BP standard documents whenever possible. Feed back lessons learned. Protect Air BP’s copyright on AEG
1.2
INTENDED USE OF THESE GUIDELINES The engineering guidance given should be used by Air BP and authorised third parties for feasibility studies, planning, detailed design, construction and commissioning of new or modified aviation fuel facilities. AEG is applicable to: 1. Airport depot installations, for the receipt, storage and supply into aircraft (via fuel hydrants or fuellers) of both kerosene and gasoline types of aviation fuels. 2. Airport fuel hydrants.
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3. Aviation fuel dispensing and related vehicles (e.g. dispensers, fuellers and pit cleaning vehicles). Designs for new facilities or for modifications to existing facilities should follow the guidance given here from the date of issue (or revision). At existing facilities it may be difficult to adopt all of the recommendations, but such improvements that are reasonably practicable should be made, taking into account the hazards that may exist at a given site and the feasibility of additional safety precautions.
1.3
NATIONAL AND LOCAL REQUIREMENTS All applicable national and local (including aviation authorities) statutory requirements and/or standards must be complied with and in the case of any conflict with the guidance given in this document the most stringent requirement shall be applied subject to fitness-for-purpose considerations. In cases of any doubt, further guidance should be sought from Air BP Centre Technical Branch.
1.4
RELATED BP AND AIR BP PUBLICATIONS The hierarchy of documentation and other publications into which AEG fits is shown on the Air BP Documentation Map, Get latest one from Albert B in PDF format.
1.5
AIR BP ENGINEERING STANDARDS References are made in AEG to detailed Air BP Engineering Specifications and Standard Drawings. A list of Air BP Engineering Specifications is also available on the Intranet. Details of Standard Drawings are available from Air BP Centre Technical Branch. Copies of specifications and drawings are available either by downloads from the Intranet or from Air BP Centre Technical Branch.
1.6
EXPLANATIONS AND EXAMPLES As far as possible, explanation for the reasoning, the background and/or examples are included in the text to help in the interpretation and application of the guidance given. Some sections of AEG including this introduction start with a list of “Key Considerations” to aid the designer.
1.7
FEEDBACK AND FUTURE REVISIONS The value of AEG to its users will be significantly enhanced by participation in its improvement and updating. For this reason, users are encouraged to inform Colin Robson (
[email protected]), the Engineering Team Leader, or the Section Owner (whose email address appears at the end of each section) with their comments in all aspects of its application.
1.8
USE OF LANGUAGE In this document, the words 'will', 'may', 'should', 'shall', and 'must', when used in the context of actions by BP or others, have specific meanings as follows: 'Will' is used normally in connection with an action by BP (or authorised third party) rather than by a contractor or supplier. 'May' is used where alternatives are equally acceptable. 'Should' is used where a provision is preferred. 'Shall' is used where a provision is mandatory. 'Must' is used only where a provision is a statutory requirement.
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1.9
DEFINITIONS AND ABBREVIATIONS Refer to Appendix A for a list the definitions and abbreviations used in the AEG.
1.10
UNITS SI metric units are used throughout these pages, with the imperial equivalents given in brackets. The use of SI units is encouraged in all cases, even where local practice differs.
1.11
DISTRIBUTION AEG should be made available to all Air BP staff and authorised third parties engaged in the design and construction of aviation fuelling facilities. Copies (or appropriate extracts) should also be issued to any BP Group staff who are engaged by Air BP in the design or construction of aviation fuelling facilities. It is intended that these pages will contain the most up-to-date copy of AEG. Paper copies, preferably limited to extracts, can be issued to those persons without access to the Intranet.
1.12
COPYRIGHT Attention is drawn to the copyright notice at the front of this document. The issue of AEG to external consultants and contractors should be strictly controlled and all copies or extracts from AEG (and associated Air BP Specifications or Standard Drawings) should be returned on completion of the project. Owner: Colin Robson (
[email protected])
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2
HEALTH, SAFETY, ENVIRONMENT AND SECURITY
2.1
INTRODUCTION...................................................................................2-2
2.1.1 2.1.2 2.1.3 2.2
Group Policy .........................................................................................2-2 Aim 2-2 HSE Expectations/Capital Value Process..............................................2-2 PRINCIPLES.........................................................................................2-2
2.2.1 2.3
BATNEEC 2-2 HSES MANAGEMENT..........................................................................2-2
2.4
SECURITY 2-3
2.5
APPLICATION OF HSES STANDARDS TO AIR BP FUEL FACILITY DESIGN AND CONSTRUCTION ..........................................................2-3
2.5.1 2.5.2 2.5.3 2.5.4 2.5.5 2.5.6 2.5.7 2.5.8 2.5.9 2.6
Design Safety........................................................................................2-3 Construction Safety...............................................................................2-3 Environmental Considerations...............................................................2-3 Legislation 2-3 Site Investigations .................................................................................2-4 Noise Control ........................................................................................2-4 Environmental Monitoring......................................................................2-4 Vapour Emissions .................................................................................2-4 Emergency Spill Containment / Clean Up..............................................2-4 CONSIDERATIONS ..............................................................................2-1
2.6.1 2.6.2 2.6.3 2.6.4 2.6.5
Element 1 – Leadership and Accountability...........................................2-1 Risk Assessment and Management ......................................................2-3 People, Training and Behaviours ..........................................................2-5 Working With Contractors and Others ...................................................2-7 Facilities Design and Construction ........................................................2-9
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2.1
INTRODUCTION
2.1.1
Group Policy BP Group HSE Policy (March 1999) makes a commitment to Health Safety and Environment performance and states three simple goals: •
No accidents
•
No harm to people
•
No damage to the environment
Air BP endorses the principles set out in the BP Group commitment to Health Safety and Environment performance and the BP Group Security Policy.
2.1.2
Aim The aim of this section is to highlight the HSE issues that can be influenced by the engineer in order to allow engineers to minimise risks by good planning, design and project management. This section uses the Thirteen Elements of BP’s HSE Management System Framework to ensure all issues are covered and to make it simple for the engineer to cross reference with the Group’s HSE Expectations.
2.1.3
HSE Expectations/Capital Value Process There is significant overlap between these two tools. Before reading this section you should be familiar with the Capital Value Process (CVP) and its terminology.
2.2
PRINCIPLES
2.2.1
BATNEEC B – Best A – Available T – Technology N – Not E – Entailing E – Excessive C - Cost
2.3
HSES MANAGEMENT Within Air BP, HSES management is viewed as a significant tool in ensuring that our business is run efficiently. The objectives are appropriate standards of employee welfare, ensuring our licence to operate and meeting Society's expectations. HSES management is important from the outset when a new facility is considered; from the initial site visit, through design, procurement, construction and commissioning to the eventual operation, all aspects of HSES need to be carefully considered. Many HSES topics will be noted throughout AEG and the associated Specifications. These range from the methodologies adopted to maintain the aviation products on specification to consideration of the Health and Safety aspects associated with the operation of the facilities and protection of the environment from damage.
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From acquisition or design, through to abandonment or divestiture the HSES risks associated with Air BP facilities, equipment and operations, should be assessed and managed. Air BP’s aim is to address HSES concerns throughout the entire life of the facilities and operations.
2.4
SECURITY Appropriate provisions need to be made to ensure the security of each operation. An overall security plan should be developed for each site taking due accounts of all existing airport security arrangements where appropriate. Reference should be made to the BP Group Security Policy.
2.5
APPLICATION OF HSES STANDARDS TO AIR BP FUEL FACILITY DESIGN AND CONSTRUCTION Specific application of HSES Standards to Air BP fuel facility design and construction are incorporated in the appropriate sections of AEG and associated Air BP Engineering Standards. However, some general points are noted in the following sections.
2.5.1
Design Safety All facilities and equipment should be designed, so as to be safe in operation and to minimise risks to personnel, our customers and the surrounding public when properly used. For aviation fuel facilities this includes the design aspects that ensure the quality of the product. The design process should consider HSES aspects through the construction, commissioning and projected life of the facility.
2.5.2
Construction Safety Construction safety covers all aspects of the physical building and commissioning of a facility so as to ensure this work is carried out in a safe manner. This involves the selection of contractors, control and monitoring of the site work and maintaining appropriate standards of safety at all times. The Client and Contractor(s) responsibility for safety needs to be clearly defined in the project documentation. GEN 5 provides a detailed guide to Construction Health and Safety. Special considerations also apply when undertaking work on existing facilities and guidance on this aspect is given in GEN 10. Further guidance on the qualification of contractors is given in GEN 15.
2.5.3
Environmental Considerations When considering both design safety and construction safety, any adverse physical effects on the environment should be minimised both in the short term (during construction) and in the longer term (during the operational life and decommissioning of the facility). The aim in the design stage is to reduce the impact of Air BP’s activities on the environment at all our facilities and throughout our operations. This should include the minimisation of waste through prevention, recycling or re-use. From the outset, consideration should be given to the means of disposal of all waste in accordance with local legislation.
2.5.4
Legislation Legal responsibilities and duties relating to safety in design and construction are established on a national basis. At all locations where Air
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BP operates, these should be understood and adhered to. In the event of conflict with Air BP practices, procedures, standards or specifications, guidance should be sought from Air BP Technical Centre.
2.5.5
Site Investigations Before the acquisition of any new site or taking over an existing site a detailed site investigation shall be carried out to determine if there is any pre-existing soil or groundwater contamination. The records of such investigations shall be agreed and filed with local authorities where possible. Reference should be made to the BP Oil Guidelines on the Evaluation of Acquisitions and Disposals (click on the link and follow the "Learning Lessons (Post Project Appraisal)" and then "Green Booklets"options)
2.5.6
Noise Control Local legislative requirements shall be adhered to and due consideration given to Air BP’s own staff, contracted staff and neighbouring third parties.
2.5.7
Environmental Monitoring All sites should include at least two appropriately located wells and routine sampling procedures to monitor for product loss into the soil or groundwater (possibly from adjacent facilities).
2.5.8
Vapour Emissions Local legislative requirements shall be adhered to.
2.5.9
Emergency Spill Containment / Clean Up Appropriate emergency spill containment and clean-up procedures and associated equipment and services need to be prepared and in place during construction and commissioning phases. National legislation shall be complied with and a comprehensive philosophy developed suitable for a given site.
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2.6
CONSIDERATIONS
2.6.1
Element 1 – Leadership and Accountability
EXPECTATION
ENGINEERING CONSIDERATIONS
Leaders model positive HSE behaviours by personal example both on and off the job, and reinforce and reward positive behaviours.
•
The Engineer should set an example to all involved in the project; contractors, site staff and anyone involved in the project.
•
Issue copies of the BP HSE Expectations to Contractors.
Leaders engage in clear, two-way communication with employees, contractors and others on HSE issues
•
Ensure all involved in the project (both internal and external) are aware of the methods of communication.
•
Encourage regular HSE reporting. This is best done in the form of a one page weekly report that asks for project progress, near miss and other HSE information. These reports should be circulated to the assets HSE coordinator and possibly the projects SPA (see Appendix ?? for an example). The reports are useful when reviewing the project in the Execute Stage.
•
If you are not based on the site during the works make contact daily.
Leaders integrate the HSE Expectations into business planning and decision-making processes, ensuring that documented systems are in place to deliver these Expectations.
•
The relevant HSE Expectations shall be considered alongside the CVP when planning any engineering projects. If the CVP is followed then this should happen.
Leaders establish clear HSE goals and objectives, roles and responsibilities, performance measures and allocate competent resources and, where necessary, specialist expertise.
•
Appoint key personnel early on in the project. If necessary bring in specialists such as site supervisors.
•
Set HSE targets in the invitation to tender.
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EXPECTATION
ENGINEERING CONSIDERATIONS
HSE mgt systems are developed, documented, implemented and supported throughout the organisation. These address health, safety, technical integrity, environmental, security, product and operational risks in accordance with the appropriate expectations.
•
Insist that all tender applications are accompanied by a detailed HSE plan that shows how the contractor manages HSE issues.
•
Provide support to contractors who are new to the BP HSE Expectations.
•
Register project on Air BP Engineering Project Database.
Leaders' HSE performance is assessed against their annual objectives, based on feedback from line management, peers and others in the Business Unit.
•
N/A
Leaders integrate Group HSE targets into their business activities. (These include, for example, external verifications, climate change, sustainable development, biodiversity and emissions reduction.
•
N/A
Leaders promote the sharing of HSE lessons learned inside and outside their Business Unit.
•
Communicate “lesson learnt” on projects to colleagues, persons working on similar projects and relevant networks (e.g. AGNES).
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2.6.2
Risk Assessment and Management EXPECTATION
ENGINEERING CONSIDERATIONS •
Encourage HSE awareness by unannounced site visits and ASAs.
•
Develop site audit checklist and use it!
•
Insist on Method Statements and accompanying risk assessments for all activities.
•
Use Air BP Spec GEN 10 to communicate Expectations.
Potential hazards and risks to personnel, facilities, the public, customers and the environment are assessed for existing operations, products, business developments, acquisitions, modifications, new projects, closures, divestments and decommissioning.
•
Provide contractors with information on all known hazards on the site.
•
Carry out Project Loss Control Reviews (PLCR) as often as you see necessary and at least when specified in the CVP.
Assessed risks are addressed by levels of management appropriate to the nature and magnitude of the risk. Decisions are clearly documented and resulting actions implemented through local procedures.
•
Follow the CVP.
•
Do not ignore financial risks.
Risk assessments and risk management / control measures are referenced in project approval documentation.
•
Ensure all Risk Assessments and Method Statements are checked and filed in the project Health & Safety file.
Risk assessments are updated at
•
The Health & Safety File is a “living” document; encourage all contractors and project staff to
Leaders put into place and promote the use of processes to identify hazards associated with BP's activities, assess risks, control the hazards and manage the risks to acceptable levels.
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EXPECTATION specified intervals and as changes are planned.
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ENGINEERING CONSIDERATIONS update risk assessments and other related information.
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2.6.3
People, Training and Behaviours ENGINEERING CONSIDERATIONS
EXPECTATION Employees and contractors practice, encourage, and reinforce safe, healthy and environmentally sound behaviours.
•
All Air BP staff involved in the project shall set an example to all contractors.
•
Insist on weekly reports. Stop work if HSE standards or procedures are violated.
HSE roles, responsibilities and accountabilities are developed and used to define individual performance targets. These are documented, and feedback on personal performance is provided.
•
Ensure all involved in the project (both internal and external) are aware of the HSE Expectations.
•
Make performance targets and penalties clear in the tender/contract documentation.
Recruitment, selection and placement process ensure that personnel are qualified, competent, and physically and mentally fit for their assigned tasks.
•
Insist on contractors’ certificates of competency, qualifications, health and insurance certificates.
BP’s workforce has the required skills and training to competently perform their tasks in a healthy, safe, and environmentally sound manner. Training is evaluated to determine its effectiveness.
•
Ensure all Air BP staff on the project are trained in the relevant skills.
•
Carry out inspections and ASAs.
With employees’ involvement, physical, chemical, biological,
•
Plan for the worst case (e.g. asbestos, equipment that has been used with Avgas – lead) and mitigate risks with control measures.
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ENGINEERING CONSIDERATIONS
EXPECTATION ergonomic and psychological health hazards are identified and the risks managed in the workplace.
mitigate risks with control measures. •
Seek expert advice (from Head Office) if unsure.
Each worksite has access to an appropriate level of medical support and to resource/facilities that promote health and wellness
•
Provide facilities, as required ensuring any use of existing site facilities does not have a detrimental effect on local staff.
•
Monitor working hours of Air BP staff and contractors (weekly report).
A programme is in place to ensure that drugs or alcohol do not impair the performance of our workforce and others on our premises.
•
Inform contractors of site policies.
New or transferred employees, contractors and other visiting personnel undergo appropriate site orientation/induction training that covers HSE rules and emergency procedures.
•
Ensure principle contractor and permit issuing authority has a suitable site induction training package. The regular site induction is almost certain not suitable.
•
Consider increasing visitor restrictions to the site. Have a “by appointment only” policy to avoid visitors impacting site safety and project productivity.
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2.6.4
Working With Contractors and Others ENGINEERING CONSIDERATIONS
EXPECTATION •
Assess contractors before committing to a contract against the Group HSE Expectations. See Appendix ?? for an example questionnaire.
•
Are internal audits undertaken?
•
Provide contractors with information on all known hazards on the site.
•
Ensure all risk assessments are recorded in the Health & Safety file and communicated to affected parties.
•
Carry out Project Loss Control Reviews (PLCR) as often as you see necessary and at least when specified in the CVP.
Interfaces between BP and suppliers of services and products are identified and effectively managed.
•
Ensure a clear contract is in place. Use BP Legal for more complex projects. Contact Head Office for a suitable example of a contract.
Clear deliverables and performance standards are agreed to and systems are put in place to assure HSE and technical compliance.
•
Break projects into manageable sections to allow simple quantification.
•
Set clear standards in the project specification (part of the contract).
•
Provide relevant Air BP Specifications and guideline.
•
Reference relevant National and IP Standards to be followed.
•
It is the engineers responsibility to check that all equipment procured (directly and
Pre-qualification and retention criteria are established for work performed by contractors, suppliers and others, including a system for assuring their compliance. Hazards and risks associated with contractor and procurement activities in our businesses are identified, managed and communicated.
Purchases products and services are,
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ENGINEERING CONSIDERATIONS
EXPECTATION where possible, verified as meeting national / international health, safety and environmental standards. Joint venture and alliance partners have HSE management systems that are aligned with those of BP’s, meet legal compliance requirements and satisfy the Group's Expectations and targets.
AEG Issue 1
indirectly) complies with Air BP Specifications, National and Industry Standards.
•
Audit all contributors to the project against HSE Expectations.
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2.6.5
Facilities Design and Construction ENGINEERING CONSIDERATIONS
EXPECTATION Baseline technical, environmental and health data are collected before the development of any new operation, facility or major modification.
Facilities are designed and constructed using technology, which balances commercial risks and financial benefits to manage technical risk and minimise or eliminate emissions, discharges, impacts on biodiversity and other environmental impacts.
Project management systems and procedures addressing technical integrity and HSE accountabilities are documented and well understood. Design, procurement and construction standards are formally approved by the designated technical/engineering authority. Formal design review, verification and validation studies are carried out based on risk assessment.
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•
Consider commissioning an (baseline) environmental audit of the site especially if it is a new location or a decommissioning.
•
Topographical and geo-technical surveys are invaluable if the ground make-up is not known or unreliable.
•
Ensure all practices follow Air BP specifications and procedures.
•
Ensure Air BP and/or the relevant Competent Authority approves all equipment used.
•
“Design out” HSE risks as much as possible.
•
Apply BATNEEC to all designs and technology with the aim of minimising impact on the environment.
•
Consider design innovations.
•
Consider commissioning and operation when designing; involve operators in the design.
•
Use CVP.
•
Carry out PLCR.
•
Apply all appropriate construction regulations e.g. CDM in the UK).
•
Apply for planning permission and other necessary permissions/consents (e.g. consent to discharge).
Air BP 2001
ENGINEERING CONSIDERATIONS
EXPECTATION Operational, maintenance and HSE expertise are integrated early in the project/design stage. Experience from previous projects and current operations is applied.
Potential hazards are identified and HSE risks assessed using appropriate risk assessment tools (e.g. quantified risk assessments, HAZOPS, and HSE reviews) at specific stages of a project from concept through to start-up, and risks are mitigated through risk management techniques.
Deviations from design standards are identified and managed at an appropriate level, with the reasons documented and retained.
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•
Appoint key personnel early on in the project. If necessary bring in specialists such as site supervisors.
•
Seek advice from asset HSE advisors.
•
Consult discipline experts.
•
Involve operations and maintenance staff in design and PLCRs.
•
Insist that all tender applications are accompanied by a detailed HSE plan that shows how the contractor manages HSE issues.
•
Provide support to contractors who are new to the BP HSE Expectations.
•
Provide Risk Assessment assistance to contractors.
•
Carry out HAZOPs for all changes.
•
Check all relevant site visit reports for required and/or suggested changes/modifications.
•
Specify in contract that all deviations from the construction drawings & specification are to be authorised by the project engineer.
•
Carry out PLCR and risk assessment(s) if changes are significant.
•
Ensure construction drawings/specifications are amended so that accurate as built drawings can be produced.
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ENGINEERING CONSIDERATIONS
EXPECTATION •
Planning permission.
•
Building warrant.
•
Consent to discharge.
Quality assurance and inspection systems are in place to ensure that facilities meet design and procurement specifications and that construction is in accordance with approved standards.
•
Arrange a GEN 500 inspection on completion of new site.
Documented pre-start up reviews are carried out for all newly installed or modified equipment to confirm that construction is in accordance with design, all required verification testing is complete and acceptable, and all recommendations/deviations are closed and approved by the designated technical authority.
•
Carry out “close-out” PLCR.
•
Document commissioning procedure.
•
Obtain necessary Competent Authority completion/compliance documentation (e.g. building certificate for buildings).
Local regulatory requirements are met or exceeded. Where these are absent or inadequate, standards are set that protect people and the environment.
No.
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•
EXPECTATION
ENGINEERING CONSIDERATIONS
Post-start up reviews are carried out for all newly installed or modified equipment to confirm that construction is in accordance with design, all required verification testing is complete and acceptable, and all recommendations/deviations are closed and approved by the designated technical authority.
•
The operate stage of the CVP.
•
Amend construction drawings so that as built drawings can be produced.
•
Do not close contracts until all “snags” have been resolved.
Applicable regulatory requirements are met or exceeded and operational/technical/mechanical integrity is maintained by use of clearly defined and documented operational maintenance
•
Follow local CA guidelines.
•
Ensure all new equipment is registered on the planned
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No.
EXPECTATION
ENGINEERING CONSIDERATIONS
clearly defined and documented operational, maintenance, inspection and corrosion control systems.
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maintenance schedule. •
Provide all relevant technical documentation to site and/or Maintenance engineer Manager.
•
Recommend inspection programmes.
Key operating parameters are established and regularly monitored. The workforce understands their roles and responsibilities to maintain operations within these parameters.
•
Ensure operating procedures are drawn up.
Clearly defined start-up, operating, maintenance and shutdown procedures are in place with designated authorities identified (e.g. permit to work, hand-over, equipment and process isolation, etc.)
•
Ensure operating procedures are drawn up.
Equipment that has been out of service for maintenance or modification is subject to documented inspection and testing prior to use.
•
Get all “recycled” equipment is reconditioned/overhauled before reuse.
Reliability and availability of protective systems are maintained by appropriate testing and maintenance programmes, including management of temporary disarming or deactivation.
•
Ensure all safety equipment is added to the planned maintenance system.
•
Write procedures for emergency equipment override.
Risks introduced by simultaneous operations are assessed and managed.
•
Carry out risk assessments in the design phase in order to mitigate risks.
HSE impacts associated with waste, emissions, noise, biodiversity and energy use are monitored and minimised.
•
Consider in design phase.
•
Operating procedures should be written so as to minimise impact.
Comprehensive waste management programmes are in place to ensure that wastes are minimised re used recycled or properly
•
Closed system sampling.
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No.
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EXPECTATION
ENGINEERING CONSIDERATIONS
ensure that wastes are minimised, re-used, recycled, or properly disposed of.
•
Provide suitable equipment to assist recycling and, if necessary, disposal of materials.
Decommissioning, remediation and restoration plans are established using risk-based studies for end of life equipment/ facilities.
•
Consider in Select stage of CVP.
A quality assurance programme exists to ensure that equipment replacement or modification maintains operations integrity.
•
Planned maintenance.
The health, safety, security, environmental, technical and other impacts of temporary and permanent changes are formally assessed, managed, documented and approved.
•
Covered by PLCR process..
Changes in legal and regulatory requirements, technical codes, and knowledge of health and environmental effects, are tracked and appropriate changes implemented.
•
Ensure you are applying up to date Standards and codes to the design.
Effects of change on the workforce/organization, including training requirements, are assessed and managed.
•
Local staff will require training on new equipment. Does the project result in more/less staff?
The impact on product quality of changes in manufacturing processes is assessed, associated hazards are evaluated and risks are controlled.
•
N/A
The original scope and duration of temporary changes are not exceeded without review and approval.
•
A waiver from the local fuels quality advisor should cover all changes affecting fuel quality.
2-13
Air BP 2001
No.
AEG Issue 1
EXPECTATION
ENGINEERING CONSIDERATIONS
A system is in place to securely manage drawings, design data and other documentation, including definition of responsibilities for maintaining this information.
•
Set up a filing system in the Appraise stage.
•
Ensure the H&S file is kept up to date and reviewed frequently.
Applicable regulations, permits, codes, standards and practices are identified. The resultant operating requirements are documented and communicated to the workforce.
•
Identify all relevant standards and codes early on and if necessary include them in tender documentation.
Pertinent records are maintained, available and retained as necessary. Obsolete documentation is identified and removed from circulation.
•
Ensure drawings are kept up to date and revisions maintained.
Scope and format of technical documentation will be agreed for each facility and will form part of the design input for new facilities and modifications.
•
Follow CVP and Air BP specification ADM 1 (documents) & ADM 20 (drawings).
Employee health, medical and occupational exposure records are maintained with appropriate confidentiality and retained as necessary.
•
N/A
Assessments are conducted for new products prior to marketing or distribution, to identify health, safety and environmental hazards and risks associated with normal use and foreseeable misuse.
•
Only use approved equipment.
Periodic reassessments are conducted for all manufactured and rebranded products and intermediate streams. This includes a review of adverse effects reported or experienced by those handling these products.
•
N/A
New uses or markets for existing products are evaluated to ensure that health; safety and environmental hazards and risks are identified and addressed.
•
N/A
2-14
Air BP 2001
No.
AEG Issue 1
EXPECTATION
ENGINEERING CONSIDERATIONS
Records of assessment, background information and conclusions are kept up-to-date throughout the product’s life and retained as appropriate.
•
N/A
Up-to-date information on health, safety and environmental hazards and risks relating to the use, storage, handling, transport and disposal of our products is available to the workforce, customers and others. Material Safety Data Sheets (MSDS), labels and other information are developed and issued to handlers and users in accordance with legislative and customer requirements, and as information changes.
•
Provide contractors will all necessary MSDS and COSHH assessment forms.
A system exists to collect and review adverse effects reported or experienced by those handling our products. Causes for concern are identified and actions are taken.
•
N/A
An effective recall system exists for products where a defect could give rise to health, safety or environmental hazards.
•
N/A
A system is in place to respond on a 24-hour basis to emergency requests for product health, safety and environmental information.
•
A contact list should be generated, circulated and maintained. The local emergency contact (in the Air BP Emergency Contact Directory) should be made aware of the project.
Open and proactive communications are established and maintained with employees, contractors, regulatory agencies, public organizations and communities regarding the HSE aspects of our business.
•
Consult the relevant Competent Authorities regarding the project design and possible impacts.
•
Ensure all consents are got before work commences (e.g. planning permission, consent to discharge).
BP recognizes and responds to government and community HSE related expectations and concerns about our operations and our
•
2-15
Air BP 2001
No.
EXPECTATION
ENGINEERING CONSIDERATIONS
related expectations and concerns about our operations and our products.
AEG Issue 1
HSE impacts of new business development on local communities are openly assessed, communicated, and integrated into the business case.
•
PLCR
HSE impacts of any divestment or decommissioning on existing operations, neighbours or local community (originally identified during the new business development stage) are reviewed, communicated and managed.
•
Keep neighbours (e.g. Airport Authority) informed of developments and changes.
Major business operations periodically issue an externally verified statement relating to HSE performance and programmes.
•
Provide the local HSE advisor with the necessary information to publish an informed bulletin.
Emergency management plans are based on the risks that potentially impact the business. These plans are documented, accessible, clearly communicated and align to the BP Group’s emergency management system.
•
Equipment, facilities and personnel needed for emergency response are identified, tested and available.
•
Personnel are trained and understand emergency plans, their roles and responsibilities, and the use of crisis management tools and resources.
•
2-16
Air BP 2001
No.
AEG Issue 1
EXPECTATION
ENGINEERING CONSIDERATIONS
Drills and exercises are conducted to assess and improve emergency response/crisis management capabilities, including liaison with and involvement of external organizations.
•
Periodic updates of plans and training are used to incorporate lessons learned from previous incidents and exercises.
•
All health, safety, technical integrity, security and environmental incidents, including near misses, are openly reported, investigated, analysed and documented.
•
Major incidents are investigated by a multi-function/level team with participation and leadership from outside the business unit.
•
Incident investigations, including identification of root causes and preventive actions, are documented and closed-out.
•
Information gathered from incident investigations is analysed to identify and monitor trends and develop prevention programmes.
•
2-17
Air BP 2001
No.
AEG Issue 1
EXPECTATION
ENGINEERING CONSIDERATIONS
Lessons learned from investigations are shared across BP and personnel take appropriate action upon receipt of such information.
•
Mutual sharing of lessons learned and good practice is encouraged within the wider energy and chemical industry.
•
HSE performance indicators (both inputs and outcomes) are established, communicated and understood throughout the organization.
•
The workforce is actively involved in periodic self-assessments of the effectiveness of processes and procedures to meet the HSE Expectations.
•
HSE performance indicators are regularly used to determine when and what management system changes are necessary. When changes occur in one HSE Element the impact on the entire management system is evaluated.
•
A system exists to continually improve HSE behaviours through observation, recording, and coaching.
•
A documented, risk-based audit programme exists to periodically evaluate progress towards HSE targets, regulatory compliance, and
•
2-18
Air BP 2001
No.
EXPECTATION
ENGINEERING CONSIDERATIONS
the effectiveness of the Business Unit management system(s).
AEG Issue 1
The Business Unit, in co-operation with the audit team, plans audits, which are objective and systematic. These are documented and conducted using expertise from inside and outside the unit.
•
Findings from learning processes (e.g. audits, incident investigations, near misses, HAZOPS, etc.) are prioritised, tracked and used to systematically improve the HSE management system.
•
The Business Unit leadership team reviews the management system to ensure it is continually delivering consistent, desired performance. Based on the review, new risk-based targets are considered and established wherever necessary.
•
Business Units report HSE performance data, as part of the Group’s HSE Reporting Requirements.
•
A process is in place whereby assurance is regularly provided to the Group Chief Executive demonstrating effective implementation of the BP HSE Policy and Expectations. Annual self-assessments against these Expectations are carried out by each Business Unit, along with external audits at least every three years.
•
2-19
Air BP 2001
3
PROJECT MANAGEMENT & CONTROL
3.1
GENERAL.............................................................................................3-2
3.2
BP GROUP TOOLS ..............................................................................3-2
3.3
STATEMENT OF REQUIREMENTS .....................................................3-4
3.4
PROJECT STRATEGY .........................................................................3-4
3.5
CONTRACTS........................................................................................3-5
3.5.1 3.5.2 3.6
Contract Strategy ..................................................................................3-5 Forms of Contract .................................................................................3-5 PROJECT CO-ORDINATION................................................................3-6
3.7
COST ESTIMATES ...............................................................................3-6
3.8
PROJECT LOSS CONTROL REVIEW PROCEDURE & RISK ASSESSMENT......................................................................................3-6
3.9
VALUE ENGINEERING ........................................................................3-7
3.10
QUALITY ASSURANCE AND CONTROL .............................................3-7
3.11
PROJECT DOCUMENTATION .............................................................3-8
3.12
POST-PROJECT APPRAISALS............................................................3-9
AEG Issue 1
3-1
Air BP 2001
3.1
GENERAL In this section, guidance is given on the management and control of projects. What is a “project” ? A project is any situation that involves change – usually new works or modifications to existing facilities but can be non-physical e.g. a reorganisation or system implementation. The first step in a successful project is to recognise that a change is taking place ! Key Considerations: Recognise the change and manage it. Use BP Group tools e.g. CVP Identify the client and key players. Define the opportunity / problem. Consider all the solutions and pros v. cons. Consider HSE issues from the start. Key decisions are at the front end (most influence). Cost of a change increases as a project proceeds. Consider all the risks and effect on the project’s payback. Develop a project strategy Use standard documents whenever possible. Do Loss Control Reviews at key stages. Review and feed back lessons learned (technical and commercial).
3.2
BP GROUP TOOLS Reference should be made to The BP Group ‘Getting HSE Right’ Expectations Document, Section 5 - Facilities Design and Construction and the BP Group Project Management Guidelines available on the Intranet. Air BP projects of estimated value > $5M must follow the BP Group Capital Value Process. Air BP projects of estimated value < $5M but > $1M must follow the Air BP Simplified Capital Value Process.
AEG Issue 1
3-2
Air BP 2001
Air BP projects of estimated value < $1M should follow the principles of the Air BP Simplified Capital Value Process. The Capital Value Process is to ensure that a project is aligned with the business strategy and is implemented efficiently. 'Front End Loading' is the term used to apply resources at an early stage where the influence is greatest and the most value can be extracted. Air BP Engineers are encouraged to participate in the Appraise and Select stages to ensure that the right technical solution is chosen.
It is important from the outset of any project to be fully aware of the factors that impact on its successful implementation. These include not only the technical design and detailed specifications, but also legal, tax, local regulations, and other factors that could enhance or detract from the project adding value to Air BP's operation and which should all be considered in the preparation of a sound commercial case. The principles of how a project is to be managed and controlled from initial concept to construction and commissioning also need to be carefully considered at an early stage. In order to highlight the phases of a typical project and the general order in which things should be done, a Project Control Checklist has been produced and is given in Appendix B. (add link) Key points to note are:
AEG Issue 1
•
It is important to clearly identify the Client, Single Point Accountability and Gatekeeper at the start of any project.
•
It is essential to understand the project's commercial objective and a preliminary Finance Memorandum should be prepared at an early stage to help understand the cost, schedule and operability drivers together with HSE implications.
3-3
Air BP 2001
•
A written Statement of Requirements (SoR) should be prepared at an early stage and formally agreed with the Client. (see below)
•
A comprehensive data gathering exercise is often necessary, with site visit(s), in order to prepare initial designs and layouts, size facilities and make first order cost estimates. During this phase, many factors other than those of a purely technical nature need to be considered which could have a significant impact on the project, both upside and downside.
•
The client needs to be able to make a business decision on the strength of the case(s) presented, which will often need to be prepared with their co-operation to develop the full commercial position. The use of risk modelling to analyse the sensitivities of the case(s) to variations in assumptions should be considered.
Lessons from similar past and current projects should be carefully considered.
3.3
STATEMENT OF REQUIREMENTS A Statement of Requirements (SoR) is an unambiguous definition of the services and/or facilities required by the Client. This may include several options yet to be evaluated, but it should be as precise and comprehensive as possible to ensure that all parties involved know what is to be delivered. The SoR should be prepared and agreed with the Client before any significant work commences on the project. Any subsequent change or deviation from the agreed SoR, whether at the request of the Client or through the design/construction process, should be noted in a revision to the SoR, clearly identifying the reason(s) for the change. A description of the contents for a typical SoR is given in Appendix C.
3.4
PROJECT STRATEGY To have the best chance of completing a project safely, to specification, on time and within budget a clear and coherent project strategy should be defined at an early stage. This should identify how the project is to be managed, the responsibilities and interfaces for all parties concerned with the project, the resources required, a cost estimate, project programme, quality assurance and control procedures, the contract and purchasing strategy, cost controls, loss control review procedures and how these should be managed. It is important to ensure that the Project Manager and project team have the relevant knowledge and experience. To ensure consistency the Project Manager should ideally be appointed prior to the preparation of the project strategy and not changed for the duration of the project. Reference should be made to a Project Co-ordination Procedure for more details of the inter-relationships, responsibilities and limits of authority.
AEG Issue 1
3-4
Air BP 2001
It is important to make sure that timescales are realistic. Tight timescales and compressed schedules are likely to force Project Management compromises that will invariably be costly. A description of the contents for a typical Project Strategy is given in Appendix D.
3.5
CONTRACTS In general terms a Contract awarded to a contractor for work associated with a project includes:
3.5.1
•
A Contract Agreement (signed by both parties)
•
Conditions of Contract (including the responsibilities of both parties, programme dates to be met and the method and timing of payments)
•
A Technical Specification (for the work or services)
•
Co-ordination Procedures.
Contract Strategy A Contract Strategy should be evolved early in the life of the project as part of the overall project strategy. It should give the number and types of contract that will result in the optimum allocation of resources and risks/responsibilities between BP, contractor(s) and the Client in order to achieve project completion to programme, budget and operability targets. Before implementation, the contract strategy must be endorsed by the appropriate BP Contract Committee prior to any authorisation required from the Client (or Partners).
3.5.2
Forms of Contract There are three principal types of contract: (a) Lump (fixed) Sum Contracts These are favoured where clear definition of the scope of work is possible and the risks and liabilities are clearly identified so that prospective contractors can estimate the time and effort and costs involved. It is essential to allow sufficient time for the preparation of the scope of work before such lump sum bids are sought, as bids against a poorly defined scope of work will typically need to be revised upwards. (b) Measured Contracts These use Bills of Materials (or Quantities) that are detailed listings of each element of construction work against which prospective contractors can quote unit cost rates. Final cost is agreed based on actual measurement of the work completed, and the Bills and measurement of work are usually prepared and administered by independent Quantity Surveyors. If the scope against which the Bill is prepared is not varied, a measured contract will effectively become a fixed (lump sum) contract. (c) Reimbursable Contracts These do not require a high degree of definition of the scope of work but need to be put together carefully so that the expenditure can be properly controlled. Such contracts can include incentives e.g. risk / reward payments based on outturn measures which could include for example cost, programme, safety, operating performance of the new asset.
AEG Issue 1
3-5
Air BP 2001
All these forms of contract can include an element of design. The design responsibilities, risks and liabilities should be clearly defined. Where a project can be adequately defined at the start, it is generally preferable to place work on a Lump Sum or Measured basis because this means payment is for the contractor's actual output rather than for the time taken. The contractor therefore has an incentive to be as efficient as possible.
3.6
PROJECT CO-ORDINATION A Project Co-ordination procedure should be prepared to clearly identify the inter-relationships between all of the parties involved in a project, the responsibilities and limits of authority. This generally covers four categories of work, which may need to be detailed as the project proceeds: (i) Initial Design / Specification, (ii) Contractor(s) (iii) Construction and (iv) Commissioning Local regulations applicable to Construction, Design and Management shall be taken into consideration to ensure that all parties involved understand their health and safety responsibilities. A description of the contents for a typical project Co-ordination Procedure is given in Appendix E (add link).
3.7
COST ESTIMATES Reliable cost estimates are essential. An underestimate may lead to a non-viable project, and an overestimate could result in rejection of a sound investment. The accuracy of an estimate is directly related to the level of technical definition - this should improve as the project develops and the financial case should be checked regularly testing the upside and downside cost estimate limits. Consideration should be given to the use of probabilistic techniques to determine the estimate accuracy or range of probable costs.
3.8
PROJECT LOSS CONTROL REVIEW PROCEDURE & RISK ASSESSMENT Loss control reviews of all projects will be carried out to ensure that the facilities are designed and constructed in the best interests of BP and in accordance with national legislative requirements, BP group policies and accepted good engineering and construction practices, so as to minimise the potential for loss. Losses include those arising from misconceived objectives, safety, design and environmental aspects as well as construction, commissioning and operational practices. Reviews shall be conducted for all new projects, major facility extensions and modifications. It is important that the opportunity to review the commercial viability of a project and its impact on surrounding activities is taken at appropriate Loss Control Reviews.
AEG Issue 1
3-6
Air BP 2001
Guidance on the type of review and the procedure to be adopted is given in GEN 40. An essential consideration during this process is Risk Assessment – you must understand the risks to the project. This is done in three stages:
FIGURE 3-1 RISK M ANAGEMENT PROCESS
The objective is to move from the RED situation where risks are not fully understood to the GREEN situation where risks are being managed. Firstly risks are identified and can be logged in a Risk Register. The risks are then evaluated in terms of probability and likely consequences. Finally, a decision can then be made on each risk: ACCEPT and do nothing MITIGATE the risk by design and/or operational practices ELIMINATE the risk e.g. don’t do something, do it differently or insure
3.9
VALUE ENGINEERING There is often scope for capital cost savings by means of a cost reduction exercise. Ideally this should be done at the design stage, considering the full cost of technically acceptable alternatives where they exist. However, a review of areas of potential cost saving should be undertaken as part of the Loss Control Review process, described above. The BP Capital Value Process includes a toolbox of Value Improving Practices.
3.10
QUALITY ASSURANCE AND CONTROL It is important to ensure that project implementation fully meets all of the standards specified and adequate records demonstrate that this so. This is achieved by following a pre-established, methodical, procedural approach to all project work by all people - project, contractor and suppliers - involved with all stages of the project.
AEG Issue 1
3-7
Air BP 2001
Before any work commences, a Quality Assurance and Control Plan should be agreed, setting out the specific quality practices to be followed. This should clearly identify all stages of supply, manufacture or construction when inspection and/or special tests are required and give details of the inspection and/or tests to be carried out, the certification to be supplied and who is responsible for the testing. In general, suppliers or contractors should be responsible for the preparation and execution of Quality Plans for their work. These should be reviewed and agreed by Air BP before the work is executed. Air BP may undertake to make additional inspections as deemed necessary, but these should not in any way absolve the supplier or contractor from their responsibilities. It is important to ensure that orders and contracts oblige the supplier or contractor to give sufficient notice of all activities and allow freedom of access for Air BP to its works throughout the period of the order or contract. The qualifications of inspection and testing personnel should be carefully vetted prior to engagement (whether working directly for Air BP, a supplier or a contractor) and their ability to adhere to the required procedures during the project regularly monitored.
3.11
PROJECT DOCUMENTATION In addition to meeting any statutory requirements, a comprehensive and up-to-date set of records (commonly known as a Project Dossier or 'AsBuilt' records) for Air BP's facilities is essential. Without such records any modification or maintenance of the facilities could be delayed while surveys and engineering audits are carried out to re-produce the necessary information to enable design changes to be made. Considerable time and money could be involved. GEN 105 gives more details of the contents of a typical project construction dossier. Meaningful loss control reviews of a project or modification also require comprehensive records to be available. At the start of a project the key document is the Process and Instrumentation Diagram, or 'P & ID'. For aviation fuelling facilities the term 'Process' is perhaps debatable as no process in the chemical sense takes place and often the term Process Flow Diagram or 'PFD' is used. A typical P & ID shows clearly all of the key items of equipment, using standard symbols, and how these are interconnected. It is not intended to be a true layout, and conventionally it is drawn to show the flow through the facilities from left to right. Critical instrumentation is shown.
AEG Issue 1
3-8
Air BP 2001
As a project proceeds it is important that any changes made to the design specified on the documentation issued for construction are fully recorded and this information transcribed to produce an 'As-Built' set of documents on completion of the project. A comprehensive set of technical records shall be kept for all new facilities and, so far as is practicable, for existing facilities. These should be based on the as-built records, updated as necessary with any subsequent changes and include: •
P & ID or Flow Diagram
•
Drawings for: area classification, electrical power supplies, control systems, fire prevention, emergency shut-down and alarm systems, general arrangement, detailed piping layouts, tank layouts, drainage and interceptor systems, cathodic protection, and so on.
•
Specifications for all pieces of equipment, including suppliers' or manufacturers' drawings and literature
•
Design and sizing calculations, including design year and ultimate design capabilities (which should be specified in the SoR)
•
Material and test or compliance certificates
•
Commissioning report
•
Records of all maintenance
•
Records of any modification, which should also be reflected in up dated 'as-built' drawings
•
Loss control reviews
•
Lease drawings showing plot boundaries and ownership limits and planning approvals
Originals of all records should be kept in a secure location and a duplicate set stored in a different location, with a backup system in operation to ensure that copies can be obtained if either the originals or duplicate set are destroyed. Working copies, not originals, should be used for day-today reference at the facility or local office.
3.12
POST-PROJECT APPRAISALS When completed, the opportunity to critically review all aspects of a project should be taken to identify any lessons that should be learned. These can be passed on to help continually improve future projects. Ideally the input, both good and bad, should be sought from all parties involved in a project including Client(s), designers, contractors, operators and other third parties. Basic project data and lessons should be advised to Air BP Centre Engineering for posting on the Air BP Intranet. Owner: Colin Robson (
[email protected])
AEG Issue 1
3-9
06 December 2001
Air BP 2001
4
PLANNING & FORECASTING
4.1
INTRODUCTION......................................................................................4-2
4.2
AIRCRAFT FUELLING METHODS ..........................................................4-2
4.2.1 4.2.2 4.2.3 4.3
Dispensing or Kerbside Pumps ................................................................4-2 Mobile Fuellers.........................................................................................4-2 Fuel Hydrant and Dispensers...................................................................4-3 SELECTION OF A MOBILE FUELLER OR A HYDRANT SYSTEM .........4-3
4.3.1 4.3.2 4.3.2.1 4.3.2.2 4.3.2.3 4.3.2.4 4.3.3 4.3.4 4.4
Technical .................................................................................................4-4 Operational ..............................................................................................4-4 Flexibility ..................................................................................................4-4 Growth .....................................................................................................4-5 Fewer Vehicles - Less Manpower ............................................................4-5 Manoeuvrability........................................................................................4-6 Cost .........................................................................................................4-6 Political Considerations ............................................................................4-7 SUPPLY ECONOMICS ............................................................................4-8
4.5
INITIAL PLANNING..................................................................................4-8
4.6
THE DESIGN YEAR ................................................................................4-9
4.7
FORECASTING FOR THE DESIGN YEAR............................................4-10
4.7.1 4.7.2 4.7.3
Peak Into-Aircraft Rate...........................................................................4-11 Total Storage Capacity...........................................................................4-11 Fuel Stock Control..................................................................................4-12
AEG Issue 1
4-1
Air BP 2001
4.1
INTRODUCTION This section gives guidance on planning for a new aviation fuelling service including selecting the most appropriate method for delivering fuel into aircraft, forecasting the demand of fuel and sizing the storage and distribution facilities. In particular, some of the factors that determine if a proposal is commercially viable are considered. Key Considerations: Accuracy of fuel demand forecasts Fuel supply method & reliability Fuel delivery volumes (vehicle / train / pipeline / ship) Airport fuel demand (volume and peak flow) Fueller vehicles or fuel hydrant CAPEX phasing Commercial aspects e.g. Joint Ventures
4.2
AIRCRAFT FUELLING METHODS There are three methods usually employed for the fuelling of aircraft. These are (i) dispensing or kerbside pumps (ii) mobile fuellers or (iii) fuel hydrants and dispensers.
4.2.1
Dispensing or Kerbside Pumps A dispensing pump installation is similar to a petrol or gasoline station. Small aircraft park next to the kerbside pump which draws product from a local tank (typical capacity 30 to 40 m3) and transfers it via a small bore hose and nozzle into the aircraft fuel tanks through a fill orifice in the top of the aircraft wing (overwing fuelling) at relatively low flow. Details of the equipment for this method of fuelling are given in Section 7. (add link)
4.2.2
Mobile Fuellers Mobile fuellers are self-propelled (usually diesel engine powered) tanker vehicles with capacities up to approximately 80 m3 (17,600 ukg) used to fuel all sizes of aircraft. Apart from a tank of product, a fueller has onboard pressure control, pumping, filtration and metering equipment. Larger fuellers also have an elevating platform to allow the operator to reach underwing fuel couplings. In use, a fueller is driven to the side of a parked aircraft and, for larger aircraft, product is pumped under pressure through one or two delivery hose(s) connected to the fuel intake coupling(s), usually in the underside of the wing (underwing pressure fuelling) or, for small aircraft, product is dispensed through a small bore hose and nozzle into the overwing fill orifice. In the depot, fueller loading, hose end pressure control testing, parking, maintenance and washing facilities will typically have to be provided. In Section 4.3 the criteria for the selection of a mobile fueller service are discussed. Guidance on the design of the depot facilities for a fueller service is given in Section 5 (add link).
AEG Issue 1
4-2
Air BP 2001
4.2.3
Fuel Hydrant and Dispensers A fuel hydrant is a piping network buried under the aircraft parking apron through which fuel is distributed from the depot (containing the storage tanks and into-hydrant pumping equipment) to hydrant pit valves located in hydrant pits in the apron. A dispenser is a self-propelled (usually diesel engine powered) vehicle that contains pressure control, filtration and metering equipment and an elevating platform to allow the operator to reach the underwing fuel couplings. In use a dispenser is driven onto the apron and is connected by an intake hose to the hydrant pit valve in the ground and by one or two hoses to the aircraft fuel intake coupling(s), usually located in the underside of the wing. Product flows under pressure from the hydrant, through the dispenser into the aircraft. In the depot, hose end pressure control testing, parking, maintenance and washing facilities will typically have to be provided. In the next section the criteria for the selection of a hydrant and dispenser service are discussed. Details of depot facilities associated with a hydrant system are given in Section 5 and for hydrant design in Section 6.
4.3
SELECTION OF A MOBILE FUELLER OR A HYDRANT SYSTEM One of the most important initial decisions to be made is whether a mobile fueller or a fuel hydrant service should be provided. It has been amply demonstrated that there is no simple answer, or a single set of standard parameters, which can be used to determine whether the use of mobile fuellers or a fixed fuel hydrant system is the best method to adopt at a specific airport. Each case must be considered on its own merits and a solution reached which may be ideal, but which is more likely to be the best compromise between such factors as capital cost, running cost, operational flexibility, expenditure phasing, available space and site location. The decision will be heavily dependent on the design of the airport, future airport development plans, aircraft parking patterns, categories of airline business and space allocations. There is no doubt that at the very largest and busiest intercontinental hub airports fuel hydrant systems are justified in both cost and operational terms. However, it is impossible to state categorically at what point a fuel hydrant becomes the undisputed solution, but in general any location where annual fuel off-take exceeds about 500,000 tonnes (approximately 625,000 m3 or 138,000,000 ukg) a hydrant is the sensible solution. Ironically, at many very small airfields with only one or maybe two, aircraft parking bays which deal primarily with feeder aircraft, executive and general aviation, a small fixed point fuel hydrant system is often the optimum solution.
AEG Issue 1
4-3
Air BP 2001
It is intermediate airports between these two extremes, which make up the majority and where actual fuel demand and perceived medium term growth is less than about 500,000 tons per annum, to which the following sections are primarily addressed. The main factors that should be taken into account at any specific location can be broadly categorised as technical, operational, cost and political and these are considered in turn below. However, as the relative importance of these and possibly other factors interact and vary from airport to airport it is very difficult to give any more than general guidance. The guidance applies to both (i) new facilities on "green field" sites at either new or existing airports, and (ii) the uprating of facilities at existing airports to meet increasing fuel demand and/or new airport developments such as the building of new or additional passenger terminals and parking apron extensions.
4.3.1
Technical At both "green field" developments and existing airports on an aircraft by aircraft basis there are no significant technical reasons for selecting a fuel hydrant in preference to the use of fuellers. Fuellers are available which singly, or in pairs, meet the requirements of all current and future projected aircraft in terms of capacity, performance and the ability to satisfy all reasonable airline demands. Fuel hydrants may be perceived to be safer due to the elimination of large fuel-carrying tanker vehicles from the airport roads and aprons and which operate in close proximity to aircraft and other ground service vehicles. For this reason, airport authorities frequently prefer fuel hydrants. However, it should be noted that no significant fueller/aircraft incidents have been reported in the past 20 years or so which would not have been equally possible with hydrant dispensers, although it must be accepted that tanker vehicles do pose a higher potential fire risk and all else being equal a hydrant system has this advantage.
4.3.2
Operational Other than cost, a fueller-based service can have two significant advantages over a comparable fuel hydrant service. These are:
4.3.2.1
Flexibility On an existing or planned open aircraft-parking apron (where for example, the precise parking position of an aircraft is not constrained by the limits of an airbridge), fuellers can provide a totally satisfactory service to all combinations of parked aircraft. In such circumstances fuel hydrants have severe limitations and cannot possibly take account of the future parking arrangements for all types of aircraft that are likely to use an open plan apron. With the trend to accommodate larger aircraft and the need to maximise the utilisation of aircraft parking space the dual use of one large stand for parking two or more smaller aircraft is more common, (such as the Multiple Aircraft Ramp 'MARS' parking arrangement used in the UK, where typically a large stand can be used for one wide bodied aircraft or two
AEG Issue 1
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Air BP 2001
narrow bodied aircraft). Consequently, the need to reconfigure hydrant pit positions to suit these new arrangements is also quite common. Although it is possible to abandon, relocate or add hydrant pits to an existing hydrant system, the cost and operational disruption can be significant, as can the safety implications of working on a system that has contained product. Changes to airport development plans (not unknown!) could render some, if not all, installed pipe-work redundant. Many airports have supplemented an existing open apron with a new "nose-in" terminal. In this case an existing fueller service could be operated alongside a new fuel hydrant. However, a mixed fuelling service is generally the worst of both worlds in operational, maintenance and economic terms and should be avoided if at all possible. 4.3.2.2
Growth It is quite possible for an airport to develop at a faster rate than that predicted during the initial planning and assessment. A fueller-based service can be supplemented at relatively short notice by the addition of airport fuel storage tanks and extra fuellers to meet short term growth predictions thus avoiding the need for heavy pre-investment. Similarly, for a fuel hydrant, additional depot tankage and dispensers can be arranged, but underground pipe-work and associated equipment to cater for the predicted life of a fuel hydrant should be installed from the outset. Despite meticulous planning a hydrant may prove to be inadequate and necessitate costly modifications, or it may prove to be unnecessarily overdesigned. Major extensions to a hydrant and a demand for higher flow rates in excess of those on which the original design was based can be very difficult to accommodate without a further costly capital investment. Equally, the under-utilisation of a over-sized hydrant is uneconomic. A fuel hydrant service has the following principal advantages:
4.3.2.3
Fewer Vehicles - Less Manpower Dispensers can move directly from aircraft to aircraft whereas fuellers with a finite fuel capacity must return to a re-loading point. As a result more fuellers, and operatives, are necessary than for an equivalent fleet of hydrant dispensers. The disparity is also influenced by the proximity of the fueller loading facilities to the aircraft parking apron, the time it takes to drive between the apron and the loading point and the time taken for loading. The cost and feasibility of a satellite fueller loading point, closer to the apron area, can be considered. Labour costs are also a factor in determining the relative merits. The number of dispensers and manpower required at any time is a function of the peak period of fuelling activity at the airport. Similarly, the number of fuellers, their capacity and hence the manpower requirements
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are also determined from the peak into-aircraft rate. However, account needs to be taken of the limited quantity of fuel that can be carried by a fueller (up to 80 m3 with the largest vehicles) and the time taken to return to a depot and reload. Consideration must therefore be given to the number of fueller loading positions and the fill rates based on the design year. As a general rule it should be possible to load a fueller at a rate at least equal to its maximum rated into-aircraft fuelling performance. It should never be necessary to load all fuellers simultaneously and as a guide there should be sufficient loading positions for one-half of the number of fuellers required during the peak period to be loaded at one time. Sufficient space should be provided for parking the maximum number of fuellers and the addition of extra loading positions to meet the design year requirements. 4.3.2.4
Manoeuvrability Most new airport terminals and aprons are designed so that passengers can board and disembark through airbridges of various forms. This arrangement necessitates the precise parking of the aircraft using each gate and thus lends itself to hydrant fuelling. When an aircraft is parked at a terminal the available space on the apron is often quickly occupied by numerous ground service vehicles, their drivers and airline representatives all working to attend to the needs of the aircraft. In such situations the manoeuvring of large fuellers is often difficult and optimum parking to facilitate the connection of fuelling hoses to the aircraft is sometimes very difficult. Although the use of fuellers is rarely impossible, dispensers have a distinct advantage with their relative ease of access. The overall dimensions of a fueller and its fully laden weight will also need to be taken into account in the design of airport roads, bridges, manoeuvring areas, tunnels and any other structure under which the fueller may need to drive.
4.3.3
Cost Once the non-quantifiable factors such as relative safety have been considered and unless there are over-riding reasons why one of the alternatives must be discarded, which is unlikely, then a selection of the best alternatives should be made on economic grounds. Subject to the political considerations discussed in the nest section this should be based on accurate costing of the operational alternatives following a detailed study of the actual airport and its predicted growth. An accurate knowledge of available equipment and the optimum manpower required to use it, as well as basic design experience, is essential in making these evaluations as on-going costs will significantly affect overall economics.
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Manpower costs are a significant part of the total cost of operating a depot and therefore manpower utilisation needs to be taken into account early in design of the depot and the fuelling service. The level of automation and remote control of equipment should be carefully considered in this context and, if not installed from the outset, thought given to making provision for installation of automation at a future time when it may be cost justified. Any local restrictions on automation, such as work practices, must be allowed for from the outset. Whilst hydrant systems may appear, at first sight, to permit the more efficient fuelling of aircraft, this is not necessarily always the case. In economic terms a fueller service can be preferable particularly where complete hydranting is either impossible or impractical and a mixed operation may result. This is equally applicable to an expansion of an existing fueller-based service and to a "green field" development. The higher capital cost of a fuel hydrant installation usually outweighs the cost differential between fuellers and dispensers at airports of intermediate size. (Obviously this differential is eroded as the throughput increases and more pieces of mobile equipment are required). The capital intensive investment for a hydrant system can be a serious disadvantage in times of capital expenditure limitations and can reinforce the case against its adoption if a fueller alternative offers comparable returns. An increasing emphasis on environmental protection measures, such as leak detection, sectionalisation and remote instrumentation and control all add to the initial capital cost of a hydrant. A thorough economic assessment should always be carried out before a decision is made to build (or support, if Air BP is part of a consortium or joint venture considering such a project) the installation of a hydrant. For new hydrant systems emphasis should be placed on minimising possible future changes by working closely with the airport authorities and/or their consultants on identifying the range of aircraft that could use a given stand and all the expansion options. Where there is a high degree of uncertainty as to future plans it may be worth aiming to include some form of compensation payment or equivalent from the airport authority as part of any lease agreement should an agreed minimum level of business not be reached. Although not as capital intensive, fueller operations should also be assessed carefully to ensure that all of the operating costs are considered.
4.3.4
Political Considerations The absolute economic justification for one or other of the fuelling methods is often outweighed by reasons of commercial competition or Authority demand. Fueller services are usually financed and operated by individual fuel suppliers or groups of suppliers. Further competitors may subsequently enter the market at an airport by doing likewise.
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As the number of competitors increase the diminishing share of business available to each fuel supplier makes investment less and less attractive to further potential suppliers. It is unusual for more than about five suppliers to be in operation at a fueller-serviced airport of medium size. It would be unrealistic and impractical for each prospective fuel supplier at an airport to invest in individually owned hydrant systems (although this happened extensively in the USA in the 1960's). It would also be impossible other than at "green field" sites. It is now the norm for new suppliers to finance and build one jointly owned fuel hydrant through which investors, current and future, can market their fuels to airlines. In some instances the Airport Authority will finance the fuel hydrant and charge a throughput fee to all users. There are disadvantages as well as benefits to this arrangement. With no investment to protect, suppliers can move in and out of the market at will to the possible detriment of the airlines.
4.4
SUPPLY ECONOMICS An assessment of all of the available methods to supply fuel to the airport facility should be made to determine the most cost effective. Important considerations are the security of the supply method (for instance, road, rail and sea transports could be delayed by bad weather) and the ability to increase or decrease the volumes. Changes in volumes may arise from the growth of the total business at a given airport or increase in the percentage of fuellings contracted to Air BP. However, the robustness of the supply (and storage and distribution) methods should also be assessed in the event of loss of business, where the quantity of product supplied decreases but fixed costs associated with the transport and/or throughput may not reduce in proportion. All methods of supplying product to the airport have their own safety or environmental risks which in turn will often cause the method to be controlled by statutory or local regulations and possibly an upper limit imposed on the quantity of product that can be transported. The prices of fuel relative to destination airports should be estimated to assess the potential for airlines to 'tanker', where additional product is taken on-board at an airport where the sum of the cost of the product and the cost involved in flying with it is less than the cost of the same quantity of product at the destination airport. This can result in sales volumes increasing or decreasing from the expected levels depending on the relative product costs and distances between airports.
4.5
INITIAL PLANNING For many projects it is often necessary to consider the development of facilities in stages and the associated spread of capital investment over a period of several years as the business level increases to the ultimate anticipated. This focuses attention on the need to formulate a strategy
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from the outset to successfully implement the project in phases and, in particular, to identify any special provisions that need to be included in the initial design. Full allowance should also be made in the commercial viability study for all such phased future developments. Some of the facilities will be written-off over a shorter period than others and either replaced, upgraded or new facilities added. Key areas to consider are: a) The method of product supply - pipeline, road, rail or sea transport, and potential for increasing the supply rate in future. b) Product reception facilities to allow for (a). c) Storage capacity required for the life of the operation, based on the security of supply and the predicted demand levels. It is often necessary at the outset to reserve space for the construction of future storage tanks. d) Into-aircraft supply - mobile fuellers or a hydrant system. e) Number of fuelling vehicles and the associated parking and manoeuvring areas. f)
Fueller loading / Dispenser test facilities.
g) Office accommodation and parking for operators. h) Vehicle Service Buildings. i)
Power Supplies.
j)
Control Systems and Automation.
k) Into Hydrant Pumping facilities. l)
Hydrant piping network.
m) Aircraft parking / hydrant pit locations (Including the aircraft mix and use and type of airbridges). n) Fire prevention and fire fighting provisions. o) Construction and commissioning. p) Future abandonment or demolition. q) Airport expansion plans. r) Local regulations A more detailed list of the areas to consider, especially where data should be gathered during initial site visits, is included in the Information Gathering Checklist in Appendix F (add link).
4.6
THE DESIGN YEAR The Design Year is the ultimate year for which the facilities are designed. Various factors influence the selection of the design year and these should be taken into account at the project justification stage. Such factors
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include known airport expansion or re-location plans or saturation levels, availability of additional land and lease restrictions. From past trends, it is now considered prudent for larger installations to assume a Design Year at least 20 to 25 years after the facilities are first commissioned and certainly at least to the termination of any lease. However, realistic planning information may only be available for 5, possibly up to 10, years ahead. It is therefore necessary to predict future trends based on the best information available in a logical manner.
4.7
FORECASTING FOR THE DESIGN YEAR The process of estimating the scale of facilities required in the Design Year is not simply based on overall volume growth, but on a combination of predicted numbers and types of aircraft required to meet estimated local and international passenger and freight demands, with the emphasis on peak fuelling period activity. For any airport depot there are three fundamental quantities that are required in order to determine the type and size of the fuel supply facilities. These are (i) the maximum total uplift of fuel for a given period, (ii) the peak instantaneous rate at which the fuel must be delivered into aircraft and (iii) the rate of growth. All three quantities should be determined for the Design Year. Essentially (i) dictates the storage capacity and supply method(s) and (ii) dictates the into plane method (by fuellers only or through a hydrant system and dispensers) and the sizing of the associated facilities (number of fuellers or number of dispensers and size of the hydrant piping and number and capacity of the pumps). The rate of growth allows the development of supply, storage tankage and the hydrant system in stages to be investigated and, in particular, the initial investment in tankage to be kept to a minimum. As a general guide, immediate construction should only cover the storage tanks required for the first five years of operation, with space reserved for the ultimate needs in the Design Year. Preference should always be for the minimum number of large tanks rather than many small tanks. However, the higher cost of construction, provision of tie-in points and operational disruption that almost certainly will be incurred if a tank is to be built in the future in an operational depot should be considered when deciding on the tankage requirements. The peak instantaneous hydrant flow-rate requirement in the Design Year is the most critical design parameter for a fuel hydrant system; although tankage, pumps, ancillary equipment and so on can be installed to cater for a short term growth and could be supplemented at intervals if required, the design and sizing of the fuel hydrant pipelines must, from the outset, take into account the peak instantaneous flow-rate requirements of the Design Year.
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4.7.1
Peak Into-Aircraft Rate Before any detailed estimates can be made of the peak rate at which fuel must be delivered into aircraft it is necessary to obtain as reliable an indication as is possible of the future level of aircraft activity. Where possible, details of the predicted airport growth levels, both in terms of aircraft movements and passengers, should be obtained from the airport authority, the airlines and/or their consultants. As far as possible, the anticipated aircraft mix (at least in terms of narrow bodied and wide bodied aircraft), the destinations, schedule and typical fuel uplifts should be obtained. If little or no information is available then initial estimates could be made by comparison of the proposed size of the airport facilities (especially number of runways and terminals) with existing airports of a similar size and utilisation. A factor that should also be considered is the differing fuel uplifts and ground times for domestic (smaller, but frequent, uplifts) and international long-haul flights, schedule and charter services (seasonal peaks) and passenger and cargo aircraft (likely to park in remote apron areas). An assessment should also be made of the possibility of airlines 'tankering' (see above) and the likely effects this would have on the volumes. If a flight schedule can be obtained, then it is possible to calculate the likely uplifts and peak fuel requirements. A description of the procedure is given in Appendix K. Where expansions to existing facilities are required then the same basic analysis should be undertaken, although this should be simpler because of the availability of existing schedules and associated uplifts. Where available, the original sizing calculations should also be reviewed to confirm the assumptions made.
4.7.2
Total Storage Capacity Total storage capacity is determined from the maximum quantity of fuel that needs to be available for a given period, the supply method and its security, batch size, operational convenience and future anticipated growth. The storage tank capacity for each airport should be carefully considered as it not only involves a considerable capital expenditure but also a significant investment in working capital cost of stock. Knowing the product supply rate (either pipeline flow or number of road bridgers, rail tankers, barges or ships per day), the time taken to fill a tank of a given size can be determined. During the time a tank is being filled and subsequently settled, fuel cannot be issued from it and therefore two tanks are the minimum required to ensure a continuous fuelling service. For larger depots, a third tank is recommended so that one tank can be filling and one settling while the third is supplying into hydrant or loading fuellers. Allowance for the time a tank will be out of service during routine cleaning, inspection and maintenance periods should also be considered. Special consideration must also be given to the additional measures that are necessary if the supply of product is from a non-dedicated means,
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such as a multi-product (common carrier) pipeline. Usually these include extra tanks dedicated to product reception and/or the means to positively segregate a tank until appropriate quality control checks have been satisfactorily completed. For an existing facility, a simple procedure for estimating the required fuel storage volume is given in Appendix M. It should be noted that the available capacity of a storage tank is less than the shell capacity (base cross-sectional area multiplied by the shell height). Allowances need to be made for the quantity of product ('dead stock') which cannot be used below the lowest operating level (dictated by the floating suction limit or low-level alarm, where fitted, and tank floor slope) and the ullage space maintained above the maximum fill level or the high level alarm. Even with the most satisfactory supply arrangements, storage tankage for 3 peak days demand or 5 average days demand, whichever is the greater, is suggested as a good initial guide, however, consideration should always be given to minimising the working capital involved in any proposal and reviewing the costs that would be incurred if there was a supply disruption and an alternative means of supply had to be arranged.
4.7.3
Fuel Stock Control In the case of new airports, or airports undergoing major re-development, it is now common practice for jointly-owned tank farms to be constructed. Each supplying company is required to deliver fuel to the jointly-owned tankage, strictly in accordance with the international specifications for the product in question. The fuel is co-mingled in the tanks before it is pumped into a fuel hydrant or loaded into fuellers; this is totally acceptable international practice as all aviation fuel from any source must meet the same minimum specification requirements. Strict control of both the supply of fuel to the airport and the fuel stored at the airport is maintained on a continual basis. Where more than one company participates in a fuel hydrant an agreed system of stock reconciliation is necessary. Reconciliation can be achieved by all companies recording their total daily volumes delivered into and drawn out of the fuel hydrant. Any imbalance between the amount of fuel drawn out of and delivered into the fuel hydrant can be made good over an agreed period. The method of reconciliation should be agreed formally with all participants so that a fair balance of supply and demand is maintained at all times and no one participant is advantaged, for instance by routinely running with a stock deficit at the expense of others. Measurement of fuel into the fuel hydrant system could be by tank dip and/or bulk meters located downstream of the depot hydrant pumps. Dispenser meters can be used to total the volumes taken out of the fuel hydrant by each participant.
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Losses or gains can be shared amongst the participants on an equitable basis such as percentage of total sales. The above is only an outline of how stock reconciliation might operate, but many joint systems operate satisfactorily on such a basis.
Owner: Colin Robson (
[email protected])
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Air BP 2001
5
DEPOT DESIGN & ENGINEERING
5.1
GENERAL INTRODUCTION.................................................................5-8
5.2
SITE SELECTION.................................................................................5-9
5.2.1 5.2.2 5.2.3 5.2.4 5.2.5 5.2.6 5.2.7 5.2.7.1 5.2.7.2 5.2.7.3 5.2.7.4 5.2.7.5 5.2.8 5.3
General .................................................................................................5-9 Method of Product Supply .....................................................................5-9 Size and Type of Facilities...................................................................5-10 Relative Location of the Fuel Depot and the Aircraft Parking Apron(s) 5-11 Airport Security and Control ................................................................5-11 Future Airport Development Plans (Master Plan) ................................5-11 Restrictions Necessary to Ensure the Safe Operation of Aircraft .........5-11 Take-Off and Approach Funnels.......................................................5-12 Side Clearances for Runways ..........................................................5-14 Side Clearances for Taxiways ..........................................................5-14 Aircraft Parking Apron Clearance Areas ...........................................5-14 Other Restrictions.............................................................................5-14 Environmental & Geo-technical Considerations...................................5-14 DEPOT LAYOUT ................................................................................5-15
5.4
ALLOWANCE FOR FUTURE EXPANSION .............................5-16
5.5
HAZARDOUS AREA CLASSIFICATION ..................................5-17
5.6
FUEL QUALITY CONTROL CONSIDERATIONS.....................5-17
5.6.1 5.6.2 5.6.3 5.6.4 5.7 5.8 5.8.1 5.8.2 5.8.3 5.8.4 5.8.5 5.8.6 5.8.7 5.8.8 5.8.8.1 5.8.8.2 5.8.8.3 5.8.8.4 5.8.8.5 5.8.8.6 5.8.8.7 5.8.8.8 5.8.8.9 5.8.8.10
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Segregation of Aviation Product ..........................................................5-17 Materials .............................................................................................5-17 Elimination of Water ............................................................................5-18 Filtration ..............................................................................................5-19 EQUIPMENT ACCESS AND OPERABILITY............................5-21 TANKAGE ................................................................................5-21 Aviation Fuel Tanks.............................................................................5-21 Sizing of Storage Tanks ......................................................................5-22 Piping Connections and Segregation ..................................................5-22 Floating Suction Arm ...........................................................................5-23 Internal Lining of Tanks .......................................................................5-24 Roof Access and Inspection Manholes................................................5-24 Tank Level Alarms ..............................................................................5-25 Vertical Tank Design ...........................................................................5-25 Tank Cone-down Floor .....................................................................5-26 Vertical Tank Foundations................................................................5-28 Integrity Monitoring of Cone-down Floor ...........................................5-30 Vertical Tank Fixed Roof ..................................................................5-34 Vertical Tank Vents ..........................................................................5-35 Roof Manholes / Nozzles..................................................................5-35 Internal Floating Metallic Blankets (Decks) .......................................5-35 Sample and Drain Lines ...................................................................5-36 Vertical Tank Shell Nozzles..............................................................5-36 Vertical Tank Heights .......................................................................5-37
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5.8.8.11 5.8.9 5.8.9.1 5.8.9.2 5.8.10 5.8.10.1 5.8.10.2 5.8.10.3 5.8.10.4 5.9
Fire Water Diverter Plate ..................................................................5-37 Horizontal Tank Design .......................................................................5-37 Above Ground Horizontal Tanks.......................................................5-40 Underground Horizontal Tanks.........................................................5-40 General Considerations.......................................................................5-41 Tank Internal Pipework.....................................................................5-41 Automatic Tank Contents Gauging ...................................................5-41 Tank Earthing...................................................................................5-41 Tank Signs .......................................................................................5-42 STORAGE TANK INTEGRITY .................................................5-42
5.9.1 5.9.2 5.10
New Tank Integrity Testing..................................................................5-42 Existing Tanks.....................................................................................5-42 BURIED TANKS.......................................................................5-42
5.10.1 5.10.2 5.11
Double Skin (Wall) Tanks ....................................................................5-43 Containment Chambers ......................................................................5-44 TANK BUNDS ..........................................................................5-44
5.11.1 5.11.2 5.11.3 5.11.3.1 5.11.3.2 5.11.4 5.11.5 5.11.6 5.11.7 5.12
Bund Capacity.....................................................................................5-44 Bund Walls..........................................................................................5-45 Bund Floor Permeability ......................................................................5-45 Concrete floor...................................................................................5-46 Membrane Protected Bund Floor......................................................5-46 Bund Sealing.......................................................................................5-47 Bund Drainage ....................................................................................5-47 Buried Tanks.......................................................................................5-48 Double Wall and Double Floor Tanks ..................................................5-48 VEHICLE HARDSTANDING AND MANOEUVRING AREAS....5-49
5.12.1 5.12.2 5.12.3 5.13
Design.................................................................................................5-49 Materials .............................................................................................5-50 Environmental Considerations.............................................................5-51 ACCESS AND SECURITY (LANDSIDE AND AIRSIDE)...........5-51
5.13.1 5.13.2 5.14
Perimeter Protection............................................................................5-51 Control of Access ................................................................................5-52 PRODUCT RECEIPT FACILITIES ...........................................5-52
5.14.1 5.14.1.1 5.14.1.2 5.14.1.3 5.14.1.4 5.14.1.5 5.14.1.6 5.14.1.7 5.14.2 5.14.2.1 5.14.2.2
Pipeline Receipt ..................................................................................5-52 Isolation............................................................................................5-53 Pig (Pipeline Cleaning Device) Receipt ............................................5-53 Filtration ...........................................................................................5-53 Pressure Relief.................................................................................5-54 Metering ...........................................................................................5-54 Product Off-Takes ............................................................................5-54 SCADA.............................................................................................5-54 Ship/Barge Jetty Offloading.................................................................5-54 Marine Discharge Arm......................................................................5-54 Jetty to Depot Pipeline......................................................................5-54
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5.14.2.3 5.14.2.4 5.14.3 5.14.4 5.15
Reception Storage............................................................................5-55 Reception Filtration ..........................................................................5-55 Road Tanker (Bridger) Offloading........................................................5-55 Rail Car Tanker Offloading ..................................................................5-56 FUELLER LOADING ................................................................5-57
5.15.1 5.15.2 5.15.3 5.16
General ...............................................................................................5-57 Basic Requirements ............................................................................5-58 Equipment...........................................................................................5-59 FUELLER DEFUELLING..........................................................5-60
5.17
FUELLER & DISPENSER TEST FACILITIES ..........................5-60
5.18
GAS OIL DISPENSING (COC) FACILITIES .............................5-62
5.19
PIPEWORK, FITTINGS AND VALVES.....................................5-62
5.19.1 5.19.2 5.19.3 5.19.4 5.20
General Arrangement..........................................................................5-62 Non-return Valves (NRVs)...................................................................5-64 Buried Depot Fuel Pipes .....................................................................5-65 Hose Couplings...................................................................................5-66 SAMPLING AND PRODUCT RECOVERY SYSTEMS .............5-66
5.20.1 5.20.2 5.20.3 5.21
Background.........................................................................................5-66 Closed Sampling .................................................................................5-67 Design and Layout Notes ....................................................................5-73 PRESSURE AND THERMAL RELIEF SYSTEMS ....................5-74
5.21.1 Tank Pressure Relief...........................................................................5-74 5.21.2 Problems with Restricting Ventilation of Tanks ....................................5-75 5.21.2.1 Effect of Tank Breathing on Free Water in Fuel................................5-75 5.21.3 Pipework Thermal Pressure Relief ......................................................5-76 5.22 WATER QUALITY MANAGEMENT, DRAINAGE AND INTERCEPTORS 5-77 5.22.1 5.22.2 5.22.3 5.22.4 5.22.5 5.22.5.1 5.22.5.2 5.22.5.3 5.23
The Objective ......................................................................................5-77 The Problem .......................................................................................5-77 Water Quality Management.................................................................5-77 Drainage Systems...............................................................................5-80 Oil Interceptors....................................................................................5-80 API ...................................................................................................5-81 3-Chamber .......................................................................................5-81 Tilted Plate Separator.......................................................................5-81 FIRE PREVENTION, PROTECTION AND FIRE FIGHTING.....5-82
5.23.1 5.23.2 5.23.3 5.23.4 5.23.5 5.23.6 5.23.7 5.23.8
General ...............................................................................................5-83 Fire Protection Philosophy...................................................................5-83 Fire Risk and Cost Benefit Analysis.....................................................5-83 Fire Prevention....................................................................................5-84 Fire Protection.....................................................................................5-84 Tank Design........................................................................................5-84 Portable Equipment.............................................................................5-85 Fixed and Semi-Fixed Equipment........................................................5-85
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5.23.8.1 5.23.8.2 5.23.9 5.23.10 5.23.11 5.24
Water Supply....................................................................................5-85 Foam Systems .................................................................................5-86 Fire Alarms and Emergency Stop Switches.........................................5-87 Liaison and Training ............................................................................5-88 Power Supplies ...................................................................................5-88 BUILDINGS..............................................................................5-88
5.24.1 5.24.2 5.24.3 5.24.4 5.24.5 5.24.6 5.25
Design.................................................................................................5-88 Locating Buildings ...............................................................................5-88 Office ..................................................................................................5-89 Vehicle Service Building......................................................................5-89 Electrical Room ...................................................................................5-90 Stores .................................................................................................5-91 PAINTING & GRADE MARKING..............................................5-91
5.26
ROUTINE INSPECTION AND MAINTENANCE .......................5-92
5.26.1 Centrifugal Pumps...............................................................................5-92 5.26.2 Pipelines .............................................................................................5-92 5.26.3 Tanks ..................................................................................................5-94 5.26.3.1 Storage Tanks at Airports.................................................................5-94 5.26.3.2 Structure Integrity and Appurtenances - Internal ..............................5-94 5.26.3.3 Structural Integrity and Appurtenances - External Checks................5-95 5.26.3.4 Storage Tanks at Minor Airfields.......................................................5-95 5.26.3.5 Level Control Testing .......................................................................5-95 5.26.3.6 Inspection and Cleaning Records.....................................................5-95 5.27 ..................................................................................................................... PUMPS .............................................................................................................................5-98 5.27.1 5.27.2 5.27.3 5.27.4 5.27.5 5.27.6 5.27.7 5.27.8 5.27.9 5.27.10 5.28
Types of Pump ....................................................................................5-98 Product Considerations .......................................................................5-98 Dual Function Pumps ..........................................................................5-99 Pump Drives .......................................................................................5-99 Diesel Drive Pumps.............................................................................5-99 Pump Siting.......................................................................................5-100 Pump Construction Details ................................................................5-100 Pump Mounting .................................................................................5-101 Pump Installation...............................................................................5-101 Pump Pipework Connections ............................................................5-101 FILTRATION AND WATER SEPARATION ............................5-102
5.28.1 5.28.2 5.28.3 5.28.4 5.28.5 5.28.6 5.28.7 5.28.8 5.28.9
Overview of Filters used in Aviation Fuel Handling ............................5-102 Approved Filtration Equipment ..........................................................5-104 Filter/Water Separators - Design and Construction ...........................5-105 Filter Rating.......................................................................................5-105 Filter Installation ................................................................................5-108 Air Elimination ...................................................................................5-109 Drain Connections.............................................................................5-109 Static Generation in Filters ................................................................5-109 Accessories.......................................................................................5-110
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5.28.10
Filter Commissioning.........................................................................5-110 FIGURES
Figure 1-1 Design drivers ...................................................................................................................... 5-8 Figure 1-2 Jet fuel supply chain........................................................................................................... 5-10 Figure 1-3 Airport fuel depot location restrictions ................................................................................ 5-13 Figure 1-16 Typical floating suction arrangements.............................................................................. 5-24 Figure 1-4 Vertical tank for aviation fuel .............................................................................................. 5-25 Figure 1-5 Tank 1 in 30 floor slope..................................................................................................... 5-26 Figure 1-6 Typical arrangement of tank floor petal plates ................................................................... 5-27 Figure 1-7 Common water trap problem in tank bottoms .................................................................... 5-28 Figure 1-8 Bitumen/sand pad foundation ............................................................................................ 5-29 Figure 1-9 Reinforced concrete raft foundation ................................................................................... 5-30 Figure 1-10 Ring wall foundation......................................................................................................... 5-30 Figure 1-11 Tank floor leak detection and containment....................................................................... 5-31 Figure 1-12 Tank floor leak detection for a bitumen/sand pad tank foundation ................................... 5-32 Figure 1-13 Tank floor leak detection for reinforced concrete raft ....................................................... 5-33 Figure 1-14 Tell-tale inspection pit at edge of tank base ..................................................................... 5-33 Figure 1-15 Tank floor leak detection for a ring wall foundation .......................................................... 5-34 Figure 1-17 Typical tank suction, drainage and sampling arrangement .............................................. 5-36 Figure 1-18 Benefits of two manholes in a horizontal tank .................................................................. 5-38 Figure 1-20 Use of removable pipe spools to facilitate manlid removal............................................... 5-39 Figure 1-19 Access chamber for an underground tank ....................................................................... 5-41 Figure 1-21 Double skin horizontal tank with monitoring fluid.............................................................. 5-43 Figure 1-22 Double skin horizontal tank with leak detection probe...................................................... 5-44 Figure 1-23 Distance from bund wall or earth bund to tank................................................................. 5-45 Figure 1-24 Fuel penetration into ground after major spill ................................................................... 5-46 Figure 1-25 Membrane installation in a tank bund............................................................................... 5-47 Figure 1-26 Tank bund drainage by gravity......................................................................................... 5-48 Figure 1-27 Double wall vertical tank .................................................................................................. 5-49 Figure 1-28 An example of a fuel receipt facility.................................................................................. 5-53 Figure 1-29 Example of a bridger off loading island ............................................................................ 5-56 Figure 1-30 A depot supplied by rail.................................................................................................... 5-57 Figure 1-31 Standard fueller depot loading island............................................................................... 5-58 Figure 1-32 Fueller and loading island requirements .......................................................................... 5-59 Figure 1-33 Main equipment on a test rig............................................................................................ 5-61 Figure 1-34 Fuel hydrant emergency stop button sign ........................................................................ 5-62 Figure 1-35 Basic piping layout for a single grade fueller depot .......................................................... 5-64 Figure 1-36 Example of a buried pipe within a containment membrane.............................................. 5-65 Figure 1-37 Typical tank closed sampling / product return system...................................................... 5-68 Figure 1-38 Provision of adequate space below a manual sampling point.......................................... 5-68 Figure 1-39 Closed sampling station adjacent to storage tank............................................................ 5-69 Figure 1-40 A typical 100-200 litre product collection tank .................................................................. 5-70 Figure 1-41 Typical large fuel depot product recovery process ........................................................... 5-71
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Figure 1-42 Into-hydrant filters closed sampling system ..................................................................... 5-72 Figure 1-43 Typical bridger offloading sampling arrangement............................................................. 5-73 Figure 1-44 Basic overview of airport fuel depot water quality management ...................................... 5-78 Figure 1-45 Detailed overview of airport fuel depot water quality management .................................. 5-79 Figure 1-46 Tilted plate separator with storm-water bypass ................................................................ 5-82 Figure 1-47 Tank base foam piping arrangement................................................................................ 5-87 Figure 1-48 A single pump bridger offloading and fueller loading facility............................................. 5-99 Figure 1-49 Microfilter (vertical vessel).............................................................................................. 5-102 Figure 1-50 Filter water separator (vertical vessel) ........................................................................... 5-103 Figure 1-51 Filter water monitor (horizontal vessel) .......................................................................... 5-104 TABLES Table 1-A Airport fuel depot filtration ................................................................................................... 5-20 Table 1-B Recommended settings for pressure/vacuum valves.......................................................... 5-75 Table 1-C Storage tank inspection intervals........................................................................................ 5-98 Table 1-D Filter water separator - Diaphragm control valve locations ............................................... 5-108
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5.1
GENERAL INTRODUCTION This AEG Section gives guidance on the layout and engineering design requirements for major airfield aviation fuel storage depots. Refer to AEG Section 7 for the requirements for minor (including small General Aviation) sites. Reference should also be made to AEG Section 6 for guidance on the design of fuel hydrant systems and associated into-hydrant pump and filtration platforms.
Figure 5-1 Design drivers The key drivers of a project design are shown in Figure 1. Each aspect should be carefully considered, including overlaps. Legislation applies to Health & Safety and Environmental issues. Cost considerations apply not only to construction, but also ongoing operational costs and even decommissioning. The layout and design of the facilities should be based primarily on safety and operational efficiency, with due regard for the need to incorporate environmental protection and expansion requirements as they arise. In addition to the airport authority, you should liase at an early stage with all of the authorities responsible for the applicable national and local statutory requirements, including building regulations, local bye laws, petroleum licensing and fire fighting, to identify all of the conditions which will impact on the layout or detailed design. This is particularly important where submissions for specific authority approval or permissions are necessary. In some cases you should submit only a preliminary outline proposal for consideration by an authority in order that agreement to the concept can be obtained (in writing) before extensive engineering design effort is expended.
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Key Considerations: •
Agree the concept and outline approvals before starting detail design
•
Civil aviation rules on depot location
•
Baseline data of geology, groundwater depth & usage
•
Airport data – access, security, services, future plans
•
Growth forecast and reliability – allowance for growth
•
Fuel supply method and delivery volumes
•
Airport fuel demand pattern and delivery method – fueller, hydrant, GA
•
Optimum storage tank capacity – number and type of tanks (above / below ground)
•
Number of fuelling vehicles and operators
•
Vehicle access and turning circles
•
Fire protection requirements
•
Provision of vehicle maintenance facilities
•
Contingency plan for fuel supply disruption etc.
•
Legislation and local regulations
•
Environmental protection measures – What if ….. ?
5.2
SITE SELECTION
5.2.1
General There are many factors that could govern the selection of the best location for an airport fuel depot (or depots) and these should all be carefully considered before any commitment is made. Some of the more common of these are discussed below under the following headings:
• • • • • • •
The method of product supply The size and type of facilities (including future expansion) and hence the plot area required The relative location(s) of the site(s) and the aircraft parking apron(s) Airport security and control requirements Future airport development plans (master plan) Restrictions necessary to ensure the safe operation of aircraft Environmental and Geo-technical (Geological) considerations
5.2.2
Method of Product Supply Fuel may be supplied to the airport by pipeline, road tanker, rail tank car, water-borne transport or a combination of these methods.
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FIGURE 5-2 JET FUEL SUPPLY CHAIN
The routing of pipelines should take into account the location of existing airport services and future expansions and, wherever practical, avoid the need to pass under taxiways or runways. Where it is unavoidable to pass under taxiways or runways the shortest possible route should be chosen and additional measures taken to protect the pipeline and extend its design life. For road tanker supplies ('bridging'), easy access should be provided from the public highway without the need for the tankers to drive on 'airside' areas in regular use by aircraft or other airport traffic, or cause disruption to 'landside' roads, especially in the vicinity of passenger terminals, cargo areas or other ground services. For rail or water-borne supply, it may not always be possible to locate the rail sidings or vessel berths adjacent to the best site for the storage depot and an intermediate reception storage facility may need to be considered.
5.2.3
Size and Type of Facilities Where it is necessary to provide both a fueller and a fuel hydrant service, both should where practical, be operated from a common fuel depot for reasons of economy. From an assessment of the peak fuel demand (see AEG Section 4) and the predicted growth rate, the tankage requirements can be estimated and, with knowledge of the other main facilities that need to be provided such as parking areas and buildings, a minimum plot area for the whole depot can be arrived at. This will enable sites of suitable size to be selected.
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Typically, tankage requirements are estimated by taking the larger of the following two results: •
5 times average daily fuel usage
•
3 times peak daily fuel usage.
The fuel supply method, reliability, diversity (of sources and supply means) and typical parcel sizes received are major factors to be considered.
5.2.4
Relative Location of the Fuel Depot and the Aircraft Parking Apron(s) In general, fuel depots that are used as a base for fuelling vehicles should be located close to the aircraft parking apron(s) and provide unrestricted access for the fuelling vehicles. Wherever possible the location should eliminate or at least minimise the need for fuelling vehicles to use public roads or airport roads open to general traffic or the need to pass through any landside / airside security checkpoints. All roads or access routes that are to be used by a fuelling vehicle should be checked to ensure that they are of sufficient size (both width and height) and any gradients are within the limitations of the fuelling vehicle(s) and that bridges, ramps, turns, tunnels, passenger air-bridges or any other structure are suitable for the axle loading and size of the vehicle (especially fully laden fuellers). Unless no alternative cost-effective option exists, the need for fuelling vehicles to cross a runway or taxiway should be avoided for reasons of safety and operational delay, particularly during periods of peak aircraft movements.
5.2.5
Airport Security and Control In some cases it may be commercially advantageous to site the fuel storage depot outside of the airport boundary ('landside') and outside of the control of the airport authority. It may also be necessary to locate all or part of a storage depot landside where the airport, national or local authorities insist on minimising the number of employees licensed for airside access, for reasons of airport security. Where storage depots are located outside the airport boundary it will usually be necessary to provide a separate fuelling vehicle parking area and crew/operations facilities on the airport close to the aircraft parking apron(s). Such forward or remote fuelling depots should also be considered in cases where fuelling vehicles would otherwise have to use public roads or the distances between the storage depot and the aircraft apron(s) are excessive.
5.2.6
Future Airport Development Plans (Master Plan) It is most important when selecting a site for an airport fuel depot to ensure that the site chosen is outside of any area allocated for future airport development, either directly or because of adjacent developments that could compromise the site (height limitation, additional fire protection, reduced access etc.). Tunnels for services and rail or road vehicles should not be routed directly under a fuel depot nor within an agreed safety zone.
5.2.7
Restrictions Necessary to Ensure the Safe Operation of Aircraft When selecting an airport fuel depot site it is necessary to take into account those zones on or around the airport in which development is restricted in the interests of safety of aircraft operations.
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Four zones need to be considered: • • • •
The take-off and approach funnels, at the ends of runways. Side clearances for runways Side clearances for taxiways. Aircraft parking apron clearance areas. These are described in more detail below and in Figure 5-3. First preference would always be to site any main fuel depot (or forward depot) outside of these zones, but this may not always be possible. The recommendations given below apply to all airports and no differentiation has been made between various methods of airport operation, such as the use of visual or instrument approach procedures. In all cases the requirements given for sighting an airport fuel depot meets the most stringent condition for aircraft operation for large airports. Where there may be a problem in meeting any of the requirements, reference should be made to the following documents:
5.2.7.1
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CAA Licensing of Aerodromes
•
ICAO Convention (Aerodromes) – Annex 14 (check ??)
Take-Off and Approach Funnels These zones are defined by a trapezium commencing 60 metres from the extreme ends of the runway in question, as illustrated in Figure 5-3, which also indicates the take-off / approach slope surfaces which limit the height of any structure within these zones.
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ABOVE GROUND TANKS PERMITTED
FULLY BURIED TANKS AND POWER LINES PERMITTED
300
8. 5
°
AREA WHERE NO FUEL DEPOT FACILITY MAY BE SITED
RUNWAY
PLAN VIEW 60m 1370
14.3 %
2% g r
gra
adien t
dien t
365m
RUNWAY
RUNWAY
150m 150m
60m ELEVATION: APPROACH AND TAKE OFF GRADIENT
ELEVATION: RUNWAY SIDE CLEARANCES
FIGURE 5-3 AIRPORT FUEL DEPOT LOCATION RESTRICTIONS
In these zones the greatest potential hazard is on the extended centre line of the runway. If it proves necessary to site an airport fuel depot within these zones, it should be located towards the side boundaries of the funnel and in all cases shall conform to the following restrictions: No fuel depot facilities shall be sited within the first 365 metres of either funnel measured from the adjacent end of the runway. Fuel depot facilities may be sited in the part of either funnel between 365 metres and 1370 metres measured from the adjacent end of the runway, provided that all fuel storage tanks and electrical power lines are fully buried. Tank fittings, pipelines, pumps, buildings and other facilities may be above ground, but the height of these shall be below the take-off/approach slope surface. Consideration shall also be given to the likely areas to be affected by takeoff/approach funnels by any future extensions to a runway.
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5.2.7.2
Side Clearances for Runways No airport fuel depot shall be sited within a runway side clearance area defined by two parallel lines 150 metres to either side of the runway centre line. Fuel depots may be sited outside of this area provided the height of any facility does not exceed the side slope surfaces defined by two planes with base lines parallel to and 150 metres from the runway centre line and a slope of 1 in 7 (14.3 %) extending upwards and outwards from the runway.
5.2.7.3
Side Clearances for Taxiways No airport fuel depot shall be sited within a taxiway side clearance area defined by two parallel lines 60 metres to either side of the taxiway centre line.
5.2.7.4
Aircraft Parking Apron Clearance Areas No part of an airport fuel depot shall be located closer than 8.0 metres (in plan view) to the largest aircraft that could park or be manoeuvred adjacent to it. (Care should be taken to review the possibility of jet-blast from aircraft manoeuvring under their own power and, if necessary this distance may need to be increased, or the airport authority approached to provide appropriate screening.)
5.2.7.5
Other Restrictions Other restrictions may also result from line of sight or ground radar limitations. It may be that the local aviation authority will not permit a depot to obstruct the line of sight from a Control Tower (or other observation location) to runways, taxiways and parking stands, or be located such that spurious radar reflections from the sides of tall tanks or buildings might occur. Whilst it is beneficial to have the depot located for easy of access by the Airport Fire Service, it should not be so close that a major fire could adversely affect operation of the fire fighting facilities.
5.2.8
Environmental & Geo-technical Considerations There are two key environmental questions that need to be addressed when considering a site location: Firstly, is there any form of pre-existing contamination on the site? Secondly, what are the environmental risks (on and off airport) in terms of potential contamination should there be any form of product release from the proposed facilities? It is important that both questions are thoroughly considered prior to any form of commitment to proceed with any development on the site. (See also AEG Section 17 and GEN 80) It is essential to understand the site geology and geo-technical suitability for a fuel depot. If no satisfactory site investigation information is available, you should commission a survey to determine: •
the nature and strength of the sub-strata
•
whether the geology is consistent over the whole site or variable
•
ground water depth
The geo-technical survey can be combined with an environmental survey to save cost. Given a choice, an impermeable stiff clay with a shallow (< 3 metres) groundwater level is preferred to a faulted, permeable rock such as
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limestone with a deep groundwater level. The former will reduce the migration of any spilled product and be easier to remediate.
5.3
DEPOT LAYOUT The layout of a fuel depot will be largely influenced by the size and shape of the site and its access to and from airport security (airside) and public areas (landside). In addition to the limitations on location or height resulting from the safe operation of aircraft, the following basic information should be available before a layout can be prepared: •
A plan of the available site (or sites if more that one option is to be assessed), with details of all relevant existing features, such as contours, means of access, services and the position relative to the airport runways, taxiways and buildings.
•
Whether the facilities are to be designed for one, aviation fuel grade Jet fuels or Avgas, or two grades (Jet fuels and Avgas).
•
The type and size of the major items of equipment, such as storage tanks, reception facilities, vehicle loading and offloading areas and pumping platforms together with buildings and number and type(s) of vehicles that have to be accommodated.
•
The number and size of any future additional storage tanks, associated equipment or buildings for which provision will need to be made.
•
Details of the use (existing and future) of the areas adjacent to the proposed site(s).
Layout of the depot should take into account the following basic principles, which are applicable to both fueller and fuel hydrant operations: -
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A one-way flow of vehicles should be maintained from the entrance to the exit of the depot. Where possible, for security reasons, the entrance and exit should be combined in a single gateway. More than one gateway may be required where the available space is restricted or in the more unusual situation where a depot straddles both airside and landside boundaries.
•
Where sites have a landside boundary, buildings for administration and operational staff as well as vehicle maintenance and stores should be located on the side of the site closest to landside to provide easy access off public roads for staff, visitors and vehicles delivering to the site. On sites with just airside access, these facilities should be located close to the entrance/exit gateway(s).
•
In most cases the storage tanks should be positioned in an area on the opposite side of the fuel depot from the buildings so as to meet safety distance requirements and allow room for storage to be added in the future. Vehicle loading, offloading, parking and manoeuvring areas are normally positioned between the buildings and the storage tanks. On large sites it may be possible to segregate vehicle manoeuvring and parking from storage areas.
•
The site should be effectively bounded by fencing or walls composed of non combustible material. Total vertical height should be not less than 2 metres unless the depot is completely located within the airport security area. Adequate access gates of suitable width for fuelling vehicles, personnel and fire fighting vehicles should be provided. 5-15
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•
Each site needs to be assessed to determine the most suitable layout given specific local conditions and taking into account required minimum safety distances between tanks, bund walls, site boundaries, loading and offloading points and buildings. The required safety distances may be dictated by local requirements and these may vary from country to country.
•
Wherever possible, buildings should be placed out of line of vapour travel as dictated by prevailing winds, geographical location etc. Buildings containing packed-oil products should be situated away from any part of the outer boundary of the depot. Packed-oil stores and filling sheds should not be less than 6 m apart. Administrative buildings should preferably be located 15 m from fueller loading or bridger unloading facilities and from the nearest point of the tank bund, or as local regulations permit.
•
Where fuel is delivered by bridgers the offloading hard-standing should be arranged so as not to prevent other bridgers and fuelling vehicles from passing.
•
As far as practicable, of all the facilities within the depot should be within sight of the control room. Adequate lighting of all areas is also necessary.
The minimum separation distance between tanks is not a simple matter. There are number of standards including the following; •
Health and Safety Executive (HSE) Guide HSG176 - The Storage of Flammable Liquids in Tanks.
•
Institute of Petroleum - Design, Construction and Operation of Distribution Installations - Model Code of Safe Practice, Part 2.
•
NFPA 30 - National Fire Protection Association (USA) - Flammable and Combustible Liquids Code.
In all cases local standards and regulations must be conformed with. If there are no local standards, then the appropriate national standards should be adhered to. If no national standards exist, then the use of one of the standards listed above may be appropriate. It is recommended that the guidance given by the HSE Guide be checked in all cases, and if local or national standards suggest distances smaller than those suggested by the HSE Guide, then those given by the HSE should be adopted.
5.4
ALLOWANCE FOR FUTURE EXPANSION In establishing the most suitable layout, allowance needs to be made for the number and size of any future additional storage tanks and associated equipment and buildings required to cater for design year predictions. Consideration also needs to be given as to how future expansion will take place without disrupting operations. For example, access for future tank construction shall be taken into account. Pump platforms should be designed so that additional pumps, filters and other equipment can be added with minimal disruption. Long runs of above ground pipes within the depot should incorporate some flanged joint connections to facilitate possible future modifications.
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Electrical power supply, transformer and other high voltage equipment should be sized to suit design year needs and switchrooms should be sufficiently large to allow for additional switchgear. An Operations Building should be planned to accommodate expansion of staff numbers e.g. operator changing and operations areas can be located at one end of the building with adjacent land reserved for expansion. Similarly, a Vehicle Service Building can have provision for one or more vehicle bays to be added.
5.5
HAZARDOUS AREA CLASSIFICATION An integral part of the layout process is the definition of Hazardous Areas. Since the need for classification of hazardous areas is not limited to the layout task, further details regarding this topic will be found in AEG Section 10.
5.6
FUEL QUALITY CONTROL CONSIDERATIONS
5.6.1
Segregation of Aviation Product All facilities utilised for handling aviation fuels shall be fully gradeseparated i.e. each product and grade of product shall be received, stored and delivered through a dedicated system (with no connection to another system). The above grade-separation requirement may be relaxed in the case of a multi-product receipt system e.g. the discharge of mixed cargo, coastal / inland waterways vessels, or for receipts from multi-product pipelines, but only provided the system is designed to facilitate the detection and appropriate downgrading of product interfaces and there is ‘positive segregation’ between the multi-product /multi-grade pipework and the downstream dedicated aviation fuel pipework. Within an aviation fuel system, there shall be segregation between batched and unbatched product. Receipt system grade-separation and batch segregation shall be achieved by ‘positive segregation’ meaning:
•
• •
an approved ‘double block and bleed’ (DBB) valve arrangement (either using a single DBB valve, or using two valves with a drain arrangement in a pipe spool between them) or, a removable distance piece (pipe spool and blind flanges) or, a spade or spectacle blind.
in conjunction with designated operational procedures. Note that these requirements are set for quality control purposes; separate arrangements shall be made for any personnel entry into a tank.
5.6.2
Materials Facilities should be designed in such a way that there is no deterioration in product quality during the various stages of handling and storage from reception to delivery into aircraft. It is therefore important to ensure that all materials that come into contact with fuel shall have no detrimental effect on the fuel quality. On the other
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hand, the materials used must not themselves deteriorate in the presence of aviation fuels. Relatively small quantities of dissolved metals, or finely divided particulate matter, can have a detrimental effect on the Thermal Stability of aviation turbine fuel. Copper or copper rich alloys shall not be used in direct contact with fuel. Zinc or zinc coated (galvanised) iron shall not be used as they also have a detrimental effect on fuel Thermal Stability. Although mild steel is compatible with fuel, it has long been accepted by the aviation industry that pipelines and tanks carrying aviation fuel should be either coated with an approved epoxy resin material or be of stainless steel. This greatly prolongs filter element life, improves commissioning and generally improves overall fuel quality control. Low strength and poor fire resistance qualities rule out the suitability of aluminium in most cases. In recent years there has been more interest in the use of plastics, especially in the form of Glass Reinforced Plastic (GRP), for smaller storage tanks or low-pressure piping. These materials appear to offer advantages, especially corrosion resistance, but the long-term benefits have yet to be proven. Tests have shown that aviation fuels can leachout the resins from GRP and could eventually lead to structural weaknesses. Resistance to mechanical damage, fire and the generation of static electricity are also areas for concern. GRP tanks may be used providing Air BP approves the resin and tank manufacturer. Plastic pipes are still on trial and not yet approved for general use. Glass is fully compatible with aviation fuels and small sections of glass may be used in low-pressure systems (in accordance with the manufacturer's limitations), such as used for product sampling, to aid visual inspection. All main airport carbon steel storage tanks, vertical or horizontal, should also be internally coated with an approved white or light-coloured epoxy material. Smaller tanks used for product recovery or sampling should either be lined with an approved white or light-coloured lining material if manufactured of carbon steel, or manufactured from stainless steel. Where stainless steel sample pipes or dip tubes are used in carbon steel sumps (for instance in storage tanks or hydrant low points), it is possible for the carbon steel to be corroded due to an electrochemical reaction between the stainless steel and carbon steel in the presence of water. If the carbon steel is fully lined, the stainless steel is kept a reasonable distance away and water is drained away on a regular basis, conditions for such a reaction to take place can be avoided as far as possible. An alternative can be to use a short length of fully lined (with an approved lining material) carbon steel for the last section into the sump. Hoses shall be of a type approved for aviation use. Pipework fittings such as swivels used on loading hoses and floating suction arms shall be self-lubricating and under no circumstances shall these be fitted with grease nipples or similar into which grease or oils can be injected and thereby contaminate the fuel. For advice on materials procurement, refer to AEG Section 12.
5.6.3
Elimination of Water In designing fuel facilities, it should be recognised that Jet fuels have a strong affinity for water. Water is always present in fuel and a small drop in temperature will cause water to come out of solution. Water that has
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condensed from the air onto tank walls and roofs will also find its way into fuel and eventually onto the tank floor. Under certain conditions the interface between accumulated water and fuel can give rise to a microbiological growth, which can have severe adverse effects on aircraft fuelling systems. The main point to note is that, as water is heavier than fuel, it will collect at any low points formed by changes in level of pipes or depressions in tank floors and therefore the fuel system must be designed in such a way that these are minimised. Where this is impractical, such as in tank sumps or in pipelines under roads, facilities must be provided to enable removal of accumulated water. The floors of vertical tanks should be constructed with positive slope of 1 in 30 to a central sump (cone down). Similarly, horizontal tanks, whether above ground or buried, should be installed at a slope of 1 in 30 to a sump at the low end. In both cases it is important that the plates are welded so that the lap joints (and butt joints) form a continuous and uninterrupted fall along the bottom of the tank to the sump so that any water that collects on the bottom may run unimpeded down to the sump. For a vertical tank, the inlet nozzle is often fitted with a 45° elbow turned down by 45° to provide a swirl component of flow to assist free water movement towards the centre sump (but care is required so as not to damage tank fittings nor to create a vortex in the tank).
5.6.4
Filtration This section covers the use of filtration for product reception, into-hydrant supply and fueller loading duties. Refer to GEN 100 – GA Engineering Guide for filtration associated with 'GA and kerbside facilities' or AEG Section 16 for filtration on mobile equipment. Refer to AEG Section 5.28 for information about the different types of filters used in aviation fuel systems. The recommended minimum levels of filtration are shown below in Table 5-A Airport fuel depot filtration.
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Location
Product
Filtration
Notes
Discharge into storage from dedicated pipeline, barge, rail tank car or road tanker
Aviation Turbine Fuels
200 mesh/linea r inch strainer minimum for small depots, but for larger depots preferably Microfilter or Filter/Water Separator
1,2,3,4,5,6,7
Ditto
Aviation Gasolin e
200 mesh/linea r inch strainer
6,7
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Location
Product
Filtration
Notes
Discharge into storage from dedicated pipeline, barge, rail tank car or road tanker
Aviation Turbine Fuels
200 mesh/linea r inch strainer minimum for small depots, but for larger depots preferably Microfilter or Filter/Water Separator
1,2,3,4,5,6,7
Ditto
Aviation Gasolin e
200 mesh/linea r inch strainer
6,7
Supply from storage into hydrant or into fueller
Aviation Turbine Fuels
Filter/Water Separator
1,5,8
Ditto
Aviation Gasolin e
Micro-filter
2,8
TABLE 5-A AIRPORT FUEL DEPOT FILTRATION
Table Notes: 1.
Filter/Water Separator meeting the performance requirements of American Petroleum Institute (API) Specifications and Qualification Procedures for Aviation Jet Fuel Filter Separators 1581, Class II, Grade B. Refer also to Air BP Specification MECH 12.
2.
A 1-Micron (nominal) Microfilter is recommended but a 5-micron microfilter is acceptable for Joint Installations. Refer to API/IP Specifications and Qualification Procedures for Aviation Jet Fuel Microfilters 1590.
3.
For Aviation Turbine Fuels at larger depots, especially those with vertical storage tanks, filter/water separators are preferred for into-storage to improve fuel quality, otherwise prolonged tank settling times will be required and tank cleaning operations may be more frequent. (At Jointly Owner Airport Depots this is a mandatory requirement as given in JIG)
4.
In locations liable to receive very large fuel volumes or fuels containing high levels of particulates, it may be necessary to install pre-filtration in order to prolong the life of the more expensive filter/water separator elements. While this need may not be apparent at the design stage it is often prudent to allow space in the pipe-work for their installation, should the need arise.
5.
If Aviation Turbine Fuels are used without a static dissipater additive then additional precautions will be necessary to reduce the static electricity hazards associated with the flow of fuel through the filtration media. Either adequate relaxation time (30 seconds minimum) must be provided between the filter and the inlet to the storage tank by means of the piping capacity or a relaxation tank or a reduced (50%) loading / filling rate observed. If a relaxation tank is used it must be designed so that it remains full of product.
6.
Filtration installed to this standard enables reduced tank settling times providing the tank is fitted with a floating suction – See Air BP Regulations for details.
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7.
The use of Filter Monitors at the inlet to Depot Storage is not recommended and shall be by agreement with Technical Branch.
8.
The use of Filter Monitors is acceptable for either grade. However, the use of Filter Monitors for hydrant inlet duty shall be by agreement with Air BP Technical Branch.
5.7
EQUIPMENT ACCESS AND OPERABILITY When the type and size of the main items of equipment have been established and their location within the fuel depot determined based on the minimum safety distances as given in AEG Section 5.3, then consideration should be given to the ease of access and operability of each piece of equipment. Ease of access should take into account the access required during both initial construction of the facility and to subsequently allow safe and efficient operation and maintenance. Typically the points that should be considered are: •
Are there adequate pedestrian and vehicle access routes, including where necessary platforms, ladders or stairs to enable unhindered operation and maintenance of the equipment? Are all valve handles at the best orientation and within in easy reach? Can all gauges etc. be clearly seen? Is there adequate room to take samples into jars or buckets, perform Millipore tests?
•
Is there sufficient space and clearance for each item of equipment that is likely to require routine inspection or maintenance (such as a filter, pump, pump motor, large valve, pipeline pig trap, oil separator, transformer), including room to lift out the item for replacement if necessary?
•
Are all platforms, high-level walkways, ladders etc. protected by hand railing and fitted with kicker plates to prevent persons and objects falling?
•
Is there sufficient headroom, especially under access platforms, or can valves be moved to more open positions ?
•
Are sufficient emergency escape routes in place?
•
Are sufficient emergency access routes and safe areas provided for fire fighting etc.?
Before a design is finalised, it is well worth considering a review of the proposals by experienced operational and maintenance staff that are likely to see any practical problems. This is often time well spent as changes to the design during or after installation can be eliminated.
5.8
TANKAGE
5.8.1
Aviation Fuel Tanks Whereas a fuel tank is designed and constructed in accordance with an industry or local standard, there are several fundamental differences required by the aviation industry before it can be used for aviation fuel. The main differences for both vertical and horizontal tanks can be summarised:
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Increased importance of covering peak periods of demand
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Product separation for filling, settling and use
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Fixed roof (for vertical tanks)
•
Sloping floor to a drain sump
•
Sump drain line for water / dirt removal and product sampling
•
Separate inlet and outlet lines
•
Outlet floating suction arm and position indicator
•
At least two manholes to facilitate visual internal inspection
•
Internal lining
•
Aviation grade markings and tank inspection signs
These specific aviation issues are discussed below.
5.8.2
Sizing of Storage Tanks Determination of the number and size of storage tanks is usually one on the first design tasks to be undertaken once initial and long term fuel throughputs (See AEG Section 4) have been established. In general, a minimum number of large tanks are preferable to numerous small tanks from considerations of cost, space and operation. In most medium-to-large installations, 3 tanks should be an adequate number to cater for operational needs (one for product receipt, one settling and one available for fuel delivery to aircraft). This arrangement also allows reasonable flexibility to remove one tank for inspection, cleaning or maintenance. Two tanks should be adequate in small depots. The initial level of capacity provided should typically cater for the first 5 years of operation. Total storage capacity will largely depend on reliability and method of supply. Where supplies are by road delivery and are reliably available on a daily basis, Air BP normally recommends that the capacity should cater for a minimum of 5 average days or 3 peak days’ sales. Smaller storage capacity may be acceptable where supply is via a dedicated (and well-protected) pipeline. The ability to vary the supply rate in an emergency (e.g. more bridgers) or to supplement it with alternative means of supply is a key factor in arriving at the optimum storage tank capacity. If this is the single fuel depot on the airport, the risk of aircraft fuelling disruption may have to be mitigated by providing more storage capacity than the optimum. The storage volume within fuel depots supplied by rail will be greatly influenced by the number and size of rail car tanks making up a train and the estimated frequency of delivery. Depot reception tanks should be sized to accommodate the contents of a complete rail delivery without the need to switch tanks. If supply is by ship, tanks should be sized to suit cargo loads but should also take into account the effects of delays due to adverse weather conditions. It may be necessary to provide separate operational and reception tanks so that fuel can be received into reception tanks and batch-tested before being transferred to operational tanks. All above ground tanks should be located in containment bunds - this is discussed in AEG Section 5.11.
5.8.3
Piping Connections and Segregation All tanks shall be fitted with separate inlet and outlet connections.
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Provision shall be made such that tanks can by positively segregated for quality control reasons. The inlet and outlet valves should preferably be of double block and bleed type, but where this is not the case then either a removable distance piece (flanged pipe spool) between two valves or a spectacle blank flange shall be provided. Where product is supplied via a non-dedicated pipeline or other nondedicated source, the receiving tank(s) pipe nozzles (including drain / sample lines linked to other tanks) shall be fitted with double block and bleed valves or equivalent means to fully isolate the tank while the product is tested prior to release for delivery into aircraft. Mechanical isolation in the form of removable distance pieces, spectacle blind flanges or drainable spools will also be required to provide isolation of a tank from 'live' pipe-work prior to entry by personnel. All other pipe to tank connections (e.g. drain and sample lines) should contain a means of positive isolation compatible with the risk.
5.8.4
Floating Suction Arm Air BP Standard Specification MECH 73 can be used to aid the specification of a floating suction arm. For aviation turbine fuels floating suction units are fitted so that product is drawn from near the surface where it will be the 'most settled' and a reduced product settling time is permitted. A stop to prevent suction of the 'dirtiest' product close to the tank floor is also fitted. The minimum distance from the floating suction inlet to the tank floor plate shall be 230 mm (9 inches) or the diameter of the arm if it is less than 230mm. The means of installing and removing a floating suction arm should be carefully considered with respect to tank shell manhole size and, if required, access for lifting the arm into the tank area. For a large diameter floating suction arm in a vertical tank, a shell manhole can be oversized to accept the swivel dimensions or a purpose-built roof hatch can be installed directly above the swivel location. A simple buoyancy check device shall be fitted to the floating suction arm. A restraining wire may be used to prevent the unit from hitting the tank roof, roof structure or rising above an angle of approximately 70 degrees to the horizontal. For Avgas tanks, a floating suction is preferred, again to achieve a reduced product settling time. However, if no floating suction is provided the inlet to the suction shall be placed at a suitable height above the tank floor. In a vertical tank this should be 400mm. Electrical continuity shall be maintained between the floating suction, buoyancy check device, restraining wires and the tank and also across any swivel joint used in the floating suction. The size of floating suction unit fitted will be dependent on product flow rates. Recommended flow rates for the smaller sizes of floating suction units are as follows; •
100 mm (4 inch) units - up to 900 litres/min (200 UK gal/min)
•
150 mm (6 inch) units - up to 2,350 litres/min (500 UK gal/min)
•
200 mm (8 inch) units - up to 4,500 litres/min (1000 UK gal/min)
For the larger sizes normally required on vertical tanks, manufacturers’ data on pressure loss / flow-rate should be studied. The use of twin units in parallel is sometimes preferable to a single unit. AEG Issue 1
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Typical installation details of single units in a horizontal tank are shown in Figure 5-4
CENTRE LINE OF TANK
PLAN OF TANK END NOZZLE CONNECTION HEIGHT EQUAL TO PIPE DIAMETER
PLAN OF TANK MANLID CONNECTION
CENTRE LINE OF TANK
ELEVATION OF TANK MANLID CONNECTION
ELEVATION OF TANK END NOZZLE CONNECTION
FIGURE 5-4 TYPICAL FLOATING SUCTION ARRANGEMENTS
The manufacturer’s recommendations for installation should be carefully followed. Care should be taken to ensure that the internal tank nozzle flange is flat-face as the mating flange on the floating suction (often cast aluminium) is usually flat-faced. Failure to observe this point could result in a broken flange on the floating suction. The floating suction inlet should be designed by the manufacturer for minimum pressure loss. Any baffle plate provided to prevent vortexing should not obstruct the flow and an inlet elbow is preferred to a fabricated ‘lobster-back’ bend. Arms 200mm diameter and larger should be provided with an air bleed hole and non-return valve (low resistance swing-check type) at the top of the inlet elbow to allow entrapped air to escape. A small drain hole (c. 5mm) should be provided in the bottom of the arm near the swivel to allow the arm to flood with product during tank commissioning or if the arm floats above the tank product level and is inadvertently drained.
5.8.5
Internal Lining of Tanks Internal surfaces of the tank and carbon steel fittings are lined with a white or light coloured material, usually epoxy based and approved by Air BP as being compatible with jet fuel. This is done to:
5.8.6
•
Prevent any surface corrosion products from entering the fuel
•
Improve the drainage of water to the central sump
•
Aid initial commissioning and ongoing internal inspection of the tank
•
Aid tank cleaning
Roof Access and Inspection Manholes All roof nozzles and openings shall be provided with tightly fitting covers to prevent entry of water and/or solid contaminants and evaporative loss.
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Manhole covers and hinged lids shall be specified to withstand the pressure and vacuum limits of the tank. Tank roof manholes with a hinged cover should be fitted with a removable internal grid (100 mm bar spacing) to prevent passage of falling personnel or large objects.
5.8.7
Tank Level Alarms This subject is covered in AEG Sections 11 and 12. All tanks fed by pipeline, barge, ship or rail (where railcars are offloaded simultaneously) or in a road-supplied depot receiving one or more bridger vehicles per day should be fitted with completely independent HI and Hi-Hi level sensors. The tank Hi-level alarm settings can be determined by reference to AEG Appendix L. If no Hi and Hi-Hi level alarm system is required or provided, every tank used for the receipt of fuel should be provided with a high-level shut-off device e.g. a float-operated valve. Tanks in large depots feeding into a fuel hydrant should have provision for a Lo-level alarm to prevent air being drawn into the pump suction manifold.
5.8.8
Vertical Tank Design Vertical tanks constructed at an airport fuel depot are the final storage before product is issued into either a fuel hydrant system or into fuellers. Special considerations are therefore given to the design of such tanks to ensure product quality and efficiency of the operation.
FIGURE 5-5 VERTICAL TANK FOR AVIATION FUEL
Vertical tanks for aviation fuel storage are normally designed for 'lowpressure' duty and rated up to 20mbar internal pressure and vacuum of up
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to 6mbar. Typical sizes for aviation storage vertical tanks range from 6m diameter x 6m high to 25m diameter to 20m high. In the absence of detailed HI-level settings, a 2% ullage volume for each tank should be included in tank sizing calculations, plus an allowance for dead stock to ensure the floating suction inlet is always covered. The tanks are made of carbon steel with butt-welded shells designed and constructed in accordance with one of the international specifications such as BS 2654, API 650 or DIN 4119 for a product specific gravity of 1.0 (to allow for water hydro-testing). Guidance on the detailed design of the tank in terms of its structural integrity is given in one of the above specifications. The associated Air BP specification MECH 200, provides more specific detail on the aviation design requirements for aviation fuel vertical tanks up to 20m high, based on the above international specifications for standard vertical tanks. 5.8.8.1
Tank Cone-down Floor To ensure good drainage of the tank and testing for product cleanliness, a cone-down bottom is used, with the bottom plates sloping at 1 in 30 from the periphery to a central sump, as illustrated in Figure 5-6. In practice a much steeper slope than 1:30 would be necessary to guarantee the free flow of any water or particulates to the central sump. There is a compromise that has to be made between this ideal and the construction difficulties associated with a steep slope.
1:30 SLOPE
SUMP
FIGURE 5-6 TANK 1 IN 30 FLOOR SLOPE
The stability of the base of the tank and foundations becomes a problem with a steep downwards slope. The typical tank bottom is not designed for membrane stresses as would occur in a steep cone-down bottom and any foundation settlement would tend to increase the stresses and possibility of floor damage. Deeper and more costly foundations are also required for a steep conedown bottom and the quantity of dead stock below the lowest operational level is increased. In general, radial petal plates are used to form the cone and various arrangements are possible depending on the tank diameter. Figure 5-7 illustrates one possibility, other arrangements are given in MECH 200.
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QUADRANT PLATES
1:30 SL
OPE TO
CENTR E
SUMP
FIGURE 5-7 TYPICAL ARRANGEMENT OF TANK FLOOR PETAL PLATES
Care is taken to eliminate water traps, which could lead to microbiological growth and product quality problems. In the radial direction the ends of adjacent plates are either overlapped and fillet welded or butt-welded, so that water can flow freely down the slope to the sump. Other than annular plates in large diameter tanks which are butt-welded, adjacent plates in the circumferential direction are normally overlapped and if their edges are aligned with the tank radii water traps are eliminated. Butt welds are used for the central pre-formed quadrant plates and the centre sump and the weld beads are dressed (by grinding) to ensure a smooth top surface. The sump itself is fabricated and tested in a workshop, as it is difficult to carry out adequate testing of the sump on site. Although it is simple to design such a bottom it requires very careful construction to end up with the specified slope all over. There are two main problems that are encountered which are illustrated in Figure 5-8. Firstly, the welding can distort the plates and flat spots or reverse slopes can result. Secondly, on poor foundations the weight of the tank and contents can cause uneven settlement that again results in local flat spots or reverse slopes. This is improved by using thicker bottom plates than required for product containment alone, welded to each other using a sequence that minimises distortion of the plates as the bottom is constructed. Details of the typical plate layouts and welding sequences are given in MECH 200.
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SHELL WEIGHT
WATER TRAPS
WELD DISTORTION
SUMP
FIGURE 5-8 COMMON WATER TRAP PROBLEM IN TANK BOTTOMS
5.8.8.2
Vertical Tank Foundations The choice of a tank foundation is largely determined by the conditions of the subsoil, tank size, expected differential settlement and the local availability of materials and construction expertise. For cone down tank bottoms, of the type used for aviation turbine fuel tanks, there is a build-up of tensile stress in the bottom plates if differential edge-to-centre settlement occurs. This tensile (membrane) stress builds up as the floor sags at the centre under the weight of the tank contents due to foundation differential settlement under load. A build up of such tensile stress will occur more rapidly in a tank with a cone down bottom than in a tank with a cone-up bottom where the bottom plates are likely to be free of any tensile stress during initial settlement. A steeper cone down bottom, such as the 1 in 30 used for aviation fuel tanks, will also cause the build-up of tensile stress to be more rapid. As an initial guide, stress based calculations show that a granular-pad type foundations should withstand a maximum edge-to-centre differential settlement equal to approximately 0.5% of the tank diameter{ for further information refer to IStructE / Soil-Structure Interaction, Chapter 7 - 7.4.3} ( e.g. 100 mm for a 20 m diameter tank). Where expected settlements approach or exceed this value then further detailed analysis will be required to confirm the suitability of this type of foundation. In all cases a soil survey and analysis should always be undertaken to confirm the applicability of the foundation for each tank. In areas where seismic activity is likely, additional analysis to ensure the stability of the foundations will be required. There are three basic types of foundation, as described below.
9. Bitumen / Sand Pad. This type of foundation is suitable for all tank diameters where the subsoil is good and relatively little settlement is expected and is the most common type of tank foundation. The granular-pad is capped with a smooth bitumen-sand layer to provide weatherproofing and it is also expected to retard corrosion of the tank bottom. Cathodic protection of the tank floor should be considered for a pad type foundation. A disadvantage is that a pad foundation takes up more space within the bund than concrete foundations. See Figure 5-9. More details can be found on drawing STD/001/1012.
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BITUMEN / SAND LAYER TANK FLOOR PLATES TYPICALLY MIN 8MM TELL-TALE DRAIN
1:20
1:30
1 1
1:30
GRANULAR PAD
LOW PERMEABILITY MEMBRANE
BUND FLOOR - TYPICALLY GRAVEL AND SAND
FIGURE 5-9 BITUMEN/SAND PAD FOUNDATION
10. Reinforced Concrete Raft This type of foundation provides a guaranteed slope of the bottom plates to the centre sump but is probably unsuitable for large diameter tanks (greater than about 15m diameter) on poor ground because of the risk of differential settlement causing cracking of the concrete slab and tank floor. For large diameter tanks on poor ground an investigation of the soil/structure interaction issues would be required and a concrete raft foundation supported by piles should be considered. See Figure 5-10. More details can be found on drawing STD/001/1011.
TANK FLOOR STEEL PLATES
REINFORCED CONCRETE (BASE SURFACE VOID
LOW MEMBRANE
TELL TALE DRAIN 1:30
GRANULAR
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Figure 5-10 Reinforced concrete raft foundation 11. Ring Wall A reinforced concrete ring wall type of foundation may be necessary to facilitate holding down of the shell in areas of seismic activity, or to prevent edge settlement for tall tanks on poor ground. Alternatively, the use of a gravel annular shell ring wall / load spreader plate below the shell should be considered. See Figure 5-11. More details can be found on drawing STD/011/1035.
TANK FLOOR PLATES
GRANULAR FILL
LOW PERMEABILITY MEMBRANE TELL TALE DRAIN 1:30
RING WALL COMPACTED GRANULAR FILL
FIGURE 5-11 RING WALL FOUNDATION
5.8.8.3
Integrity Monitoring of Cone-down Floor Historically, leakages from tank bottoms are detected only when they become sufficiently large to show as a stock loss. Experience has shown that most bottom leaks are too small to be detected in this way and a significant product loss can occur over a long period of time. Therefore, special provision should be made to facilitate detection and also to ensure that any fuel that does escape is prevented from entering and polluting the ground and groundwater. •
Double Bottom Tanks
One way of providing tank bottom leak detection and containment is to use a double bottom construction. This can be achieved in two ways, either by adding a second steel plate bottom to the inside of the tank, or by constructing a stainless steel floor membrane within a tank, see Figure 5-12.
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STEEL PLATE
SAND
ADDING A SECOND STEEL PLATE TO THE BASE OF THE TANK
STEEL PLATE
STAINLESS STEEL LINER SPACER MESH
CONSTRUCTING A STAINLESS STEEL FLOOR MEMBRANE WITHIN THE TANK
FIGURE 5-12 TANK FLOOR LEAK DETECTION AND CONTAINMENT
•
Single Bottom Tanks One way of providing tank bottom leak detection and containment has already been described - double wall and double bottom tanks. All single bottom tank/foundation arrangements shall include a tank bottom leak detection system and/or a low permeability barrier to protect the subsoil and groundwater from product contamination. This can be achieved for the types of foundation described above in the following ways: •
Leak Detection for Bitumen / Sand Pad Foundations Tank bottom leak detection can be incorporated in this type of foundation by installing a low permeability membrane either within or under the pad. Precise details will depend on the diameter and height of the pad. For small tanks it may be possible install the membrane with a continuous fall across the bund but in larger tanks it may be necessary to install the membrane with a slope falling from the centre of the tank towards the circumference and terminate in a drainage channel where provision can be incorporated for inspection. See Figure 5-13. More details can be found on drawing STD/001/1012.
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AREA WHERE FUEL LEAKAGE BECOMES VISIBLE
KERB FINISHED BUND LEVEL
75 DIA TELL-TALE DRAIN
LOW PERMEABILITY MEMBRANE BUND FLOOR - TYPICALLY GRAVEL AND SAND
FIGURE 5-13 TANK FLOOR LEAK DETECTION FOR A BITUMEN/SAND PAD TANK FOUNDATION
•
Leak Detection for Reinforced Concrete Raft In the case of the reinforced concrete raft type of foundation, the concrete slab itself forms the barrier with the concrete upper surface made more resistant to fuel seepage by means of an approved brush-applied sealant. A void is formed under the central sump into which any leaking product should collect. One or more 'tell-tale' pipes are connected to a void formed in the concrete raft around the central sump and the pipes run downwards at a slight fall to the edge of the tank foundation. By checking the pipe outlets on a regular basis, any leak in the tank bottom, which should result in product accumulating in the void around the sump, will be detected. See Figure 5-14. Further details can be found on Air BP drawing STD/001/1011.
VOID WHERE FUEL WOULD GATHER IN CASE OF LEAK TANK FLOOR STEEL PLATES REINFORCED CONCRETE PAD (BASE SURFACE SEALED)
1:30
LOW PERMEABILITY MEMBRANE
TELL-TALE DRAIN TO MONITORING POINT SAND/CEMENT SUMP SUPPORT
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FIGURE 5-14 TANK FLOOR LEAK DETECTION FOR REINFORCED CONCRETE RAFT
Providing an impermeable bund floor has been installed, product leaving the telltale pipes will eventually end up in the depot oil interceptor. If the bund floor construction is not concrete or other low permeability material, then it will be necessary to terminate the telltale pipes in an inspection pit or in a circumferential drain. If the tell-tale drain terminates below the level of the bund, then an inspection pit is required, see Figure 5-15.
TANK WALL
TANK FLOOR PLATES INSPECTION PIT COVER INSPECTION PIT WHERE FUEL LEAKAGE IS DETECTED
BUND LEVEL
TELL-TALE DRAIN FROM CENTRAL VOID
FIGURE 5-15 TELL-TALE INSPECTION PIT AT EDGE OF TANK BASE
•
Leak Detection for Ring Wall Like the bitumen/sand pad a low permeability membrane is used. Depending on the depth of the foundation, it may be possible to install the membrane underneath the ring wall. However, if this is not practical, it can be installed within the ring beam in which case it must be properly sealed to the inner wall. See Figure 5-16. Further details can be found on Air BP drawing STD/001/1035. Depending on the depth of the foundation, it may be possible to install the membrane underneath the ring beam. However, if this is not practical, it can be installed within the ring beam in which case it must be properly sealed to the inner wall. With this arrangement, tell-tale pipes should be installed from just over the membrane surface to the outside of the ring beam to facilitate inspection. See Figure 5-16.
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RING WALL
LOW PERMEABILITY MEMBRANE STAINLESS STEEL FASTENERS
STAINLESS STEEL FASTENERS
TO MONITORING CHAMBER
FUEL RESISTANT FLEXIBLE 'Z'SEAL
FUEL RESISTANT FLEXIBLE 'Z' SEAL
FIGURE 5-16 TANK FLOOR LEAK DETECTION FOR A RING WALL FOUNDATION
•
Tell-Tale Pipes In all of the foundations, 'tell-tale' pipes should be incorporated to provide a first warning of any product leakage. These are typically 50mm or 75 mm diameter heavy-duty uPVC or galvanised steel pipes, located within the foundation. The pipes are perforated along their length and located above the impermeable membrane for the sand pad and ring beam type foundations or, for the concrete raft, connected to the void formed under the central sump. By checking the pipe outlets on a regular basis, any leak in the tank bottom will be detected. The tell tale pipes would normally terminate in an inspection pit or in a circumferential drain. Details of the arrangements are shown in the figures and reference drawings above.
5.8.8.4
Vertical Tank Fixed Roof For airport storage, tanks with a fixed roof are used to minimise ingress of water and airborne debris. Two types of roof are used, cone and dome. The most obvious difference between these is that the dome roof is selfsupporting, whereas the cone roof needs an internal frame. Although structurally sound, the cone roof does have some disadvantages in product quality terms. The roof plates and the supporting structure are a source of corrosion products. Even when lined, corrosion products can form either within crevices, created at the overlaps between adjacent roof plates, or between the roof plates and the supporting steelwork, where effective lining is hard to achieve. In order to eliminate the crevice and enable complete lining, a sealing 'wash' fillet weld is added to the underside of roof plate overlaps. Spacers to keep the roof plates away from the supporting steelwork are recommended to allow blast cleaning and lining between the two surfaces.
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It is recommended to minimise the frangible joint crevice between the roof plates and the curb angle to facilitate blasting and lining. The use of mastic filler here is not recommended. A self-supporting dome roof of butt-welded construction has an advantage over the cone roof as the internal surface of the roof is free from any supporting steelwork or crevices. It is important to note, however, that the extra strength of a dome roof means that a frangible roof-to-shell joint in the form of a weak weld cannot be used and an alternative means of emergency venting has to be provided. Routine access to roof fittings is also more difficult, especially with the more rounded domes, and the roof fittings may need to be grouped together to minimise the extra roof stairs and safety rails that are necessary. 5.8.8.5
Vertical Tank Vents Tank venting capacity should be based on API 2000. A minimum of two vents (100% redundancy) shall be provided with each vent having sufficient air/vapour flow capacity to suit normal conditions of tank filling and discharge without the pressure or vacuum in the tank exceeding the tank design criteria. Jet fuel tank free vents shall be fitted with coarse mesh screens (as specified in Appendix J) solely to prevent the ingress of birds, large insects or airborne debris. Unless local statutory regulations stipulate otherwise, fine mesh screens which act as flame or spark arrestors should not be used as these have a higher risk of blockage which may cause a tank to be damaged or even to collapse. Typically, this screen should be manufactured from mesh 12mm x 12mm x 18 SWG. In certain areas, where an excessive amount of atmospheric dirt, sand, dust or industrial pollution etc., may be experienced, consideration should be given to the fitting of micronic air filters to tank free vents. The design of the micronic air filters should be such that that when the maximum differential pressure across the filter media is reached (which should be no greater than 25mm (1 inch) water gauge) a visual indication is given, and additionally the filter is by-passed to enable the tank to vent freely. For Avgas tank venting, Pressure & Vacuum (P&V) vents should be used for both above and below-ground tanks.
5.8.8.6
Roof Manholes / Nozzles Two roof manholes are fitted to aid routine gas freeing and visual internal inspections. Combined with the light colour of the internal lining, sufficient light can enter the tank through one manhole to allow a visual inspection through the second, perhaps with the aid of a torch. One manhole should be located enable visual inspection of the floating suction arm inlet.
5.8.8.7
Internal Floating Metallic Blankets (Decks) Internal floating metallic blankets (decks) are recommended in vertical tanks for the storage of: •
Jet fuel not containing a static dissipater additive and where the product temperature may exceed 32 deg. C (90 deg. F).
•
Avgas.
These decks assist with the dissipation of static electricity and need to be adequately bonded to the tank structure. In some locations the use of blankets may be required by local legislation to reduce the emission of product vapours. Where such blankets are
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installed pressure & vacuum valves may not be necessary, unless required by statutory regulations. 5.8.8.8
Sample and Drain Lines All tanks shall be fitted with an internal drain line that turns down into the central sump for routine draining of water and sediment. The drain line should be of stainless steel pipe with a minimum 40mm diameter and should be fitted with a tankside gate valve and ball valve to permit sampling to be carried out at full flush. If the tank sump is not lined or maintained free of water there is a possibility of galvanic corrosion between the stainless and carbon steels which could result in a leak. This, of course, should not be a problem at airport installations where the quality control practices ensure the sump is kept free of water, but it is a point that should be carefully checked during tank inspections. The clearance under the end of the drain-line should be between 25-35 mm to ensure effective draining. For maintenance of larger tanks a fast drain down line may be required, typically 100mm (4") diameter. These lines may be permanently connected to the tank pump suction line, providing a spade is used to prevent inadvertent bottom draw-off (see Figure 5-17). An approved double block and bleed valve arrangement giving visual indication of positive sealing, may be used in place of conventional ‘spade’ flanges.
SUMP DRAIN 25MM TO 40MM BORE
ANGULAR POSITION OF PIPES TO SUIT
OPTIONAL TERMINATION POSITION FOR SMALL TANKS TANK BOTTOM DRAIN LINE TYPICALLY 75MM OR 100MM
TANK BOTTOM DRAIN TERMINATION AT SUMP SPADE ESSENTIAL IF DRAW-OFF LINKED TO PUMP SUCTION
CENTRAL SUMP
PUMP SUCTION LINE
FLOATING SUCTION
FIGURE 5-17 TYPICAL TANK SUCTION, DRAINAGE AND SAMPLING ARRANGEMENT
5.8.8.9
Vertical Tank Shell Nozzles There should be a separate inlet and outlet, preferably only one of each. A minimum of two shell manholes, each 600mm diameter (24 inches) shall be provided to aid gas freeing and tank entry. One shell manhole should be located near to the foot of the main tank stairway as this is likely to have convenient access. See the floating suction arm section for advice on this access requirement. For other shell nozzles, a minimum size of 50 mm is specified for strength, especially around the tank base where the nozzles may be subject to
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external loads. Necks of all nozzles should be kept as short as practicable to aid internal lining. Inlet pipes should discharge near the bottom of the tank and be designed to minimise turbulence, especially where this could cause damage to internal fittings, such as the floating suction. The maximum permissible product flow velocity into empty storage tanks is 1 m/s (3 ft/s). Once inlet connections are submerged the velocity restriction is increased to 7 m/s. This should be considered when designing tank inlet connections. Connections at the shell or bottom of a tank, through which the tank contents might be lost as a result of fracture should be of an all welded steel construction throughout. Where there is the possibility of tank movement due to ground settlement, then special consideration should be given to the flexibility of pipe or other connections made to the tank. Adequate pipe flexibility or spring supports should be considered. Where base foam injection nozzles are provided a bursting disc and nonreturn valve are fitted to ensure that there is no contact between the foam mixture and the product during normal operation of the tank (See AEG Section 5.23.8.2). 5.8.8.10
Vertical Tank Heights If tanks of different heights are connected through common filling, suction or sampling piping there is a possibility of the product in the higher tank flowing into the lower tank and resulting in an overflow. Generally Air BP prefers to avoid the problem by constructing tanks of the same height, but if this is not possible, then at least appropriately located non-return valves should be installed, together with Hi-Hi level alarm protection and careful operating procedures as appropriate.
5.8.8.11
Fire Water Diverter Plate For large vertical tanks where water cooling using mobile equipment may be a problem, consideration should be given to fitting a fixed firewater riser pipe to the roof apex together with a diverter plate at the shell to roof joint to guide cooling water down the tank shell.
5.8.9
Horizontal Tank Design Horizontal tanks constructed at an airport fuel depot are the final storage before product is issued into either fuellers or a mini fuel hydrant system. Special considerations are therefore given to the design of such tanks to ensure product quality and efficiency of the operation. Wherever possible tanks should be installed above ground as this avoids the potential environmental problems associated with buried tanks and they can be removed more easily at the end-of-life or for commercial reasons. Horizontal tanks are generally of carbon steel, butt-welded and designed to BS 2594, API ?? or DIN 6608 (Part 1 single skin and Part 2 double skin tanks) for a product specific gravity of 1.0 (to allow for water hydrotesting. Guidance on the detailed design of the tank in terms of its structural integrity is given in one or more of the above specifications. The associated Air BP Specification MECH 251 provides more specific detail on the aviation design requirements based on the above international specifications for standard horizontal tanks.
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Horizontal tanks shall be installed to a longitudinal slope of 1:30 to guarantee the free flow of any water or particulates to the drain sump. The tank support saddles and tank access manholes should be manufactured level allowing for the 1:30 fall. Two manholes are recommended, see Figure 5-18, one situated each end of the tank. This makes visual inspection without entry much easier and improves ventilation when preparing a tank for entry. VISION
LIGHT
DEPTH 230MM
VENTILATION
DIA 300MM PE MINIMUM OF 1:25 SLO
SUMP
TWO MANHOLES PROVIDE VENTILATION AND ALLOW LIGHT INTO THE TANK
FIGURE 5-18 BENEFITS OF TWO MANHOLES IN A HORIZONTAL TANK
For a horizontal tank, it is desirable to locate the tank inlet pipe at the opposite (high) end to the sump in order to promote flow of water droplets along the bottom of the tank towards the sump. From a fuel quality viewpoint, it is preferable that the outlet (suction) pipe is also located at the end of the tank furthest from the sump, but this may not be practical for long, thin tanks as it increases the 'dead stock'. There may be other considerations (especially for a long, thin above-ground horizontal tank) such as optimum pipework layout, access to manholes etc. which lead to both inlet and outlet nozzles being installed at the sump (low) end of the tank – this is acceptable providing the floating suction inlet is well clear of the sump. To facilitate lifting a manhole cover for inspection, cleaning or repairs, and moreover to protect the internal tank lining from damage, all pipe-work through a manhole cover should be flanged to spools as shown in Figure 5-19 such that it can be removed before lifting the manhole cover.
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PIPEWORK SPOOL TO FACILITATE MANLID REMOVAL
TANK MANHOLE
10 600
FIGURE 5-19 USE OF REMOVABLE PIPE SPOOLS TO FACILITATE MANLID REMOVAL
The size of all tank manholes is to be 600 mm (24 inches) diameter minimum. There should be one fill and one water draw-off connection situated in the manhole cover at the low end of the installed tank. The fill connection should be taken to the tank bottom, but should be clear of the tank floor by a distance at least equal to one-half of the diameter of the fill pipe. The fill pipe should also be located clear of the tank sump. A single vent is acceptable for a horizontal tank of 55m3 or lower capacity that is emptied at a flowrate not exceeding 5000 litre/minute. All horizontal tanks should be constructed with a sunken water sump located at the lowest end see Figure 5-18. This should be at least 300 mm (12 inches) in diameter, and 230 mm (9 inches) deep. The water draw-off connection should be a 25 mm (1 inch) standpipe fitted into the manhole cover and it should extend to within 12 mm (0.5 inches) of the bottom of the sump. If the sump drain line is stainless steel and the tank carbon steel, consideration should be given to possible electrochemical corrosion of the sump – see comment for vertical tanks. The upper end of the pipe should be provided with a suitably screwed connection and cap to permit the connection of a draw-off pump. A dip connection should be fitted on the tank centreline, either in the fill manhole or at the middle of the tank (if a Customs requirement). A flat reference plate made from 6 mm (0.25 inches) plate should be installed just clear of the tank floor (to allow water drainage) at the bottom of the dip pipe; the pipe should extend to within 10 mm (0.5 inches) of the reference plate. Alternatively, the dipstick should be provided with a suitable collar to prevent it from striking the tank bottom. The dip pipe should incorporate a suitable vapour release hole within the tank, to prevent the danger of false measurements. Aluminium dip-sticks are not recommended for use within steel tanks due to the danger of sparking should the aluminium strike the steel.
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Tank calibration will be necessary during commissioning and may be necessary after a period of time due to tank settlement, or possibly distortion in the case of an underground tank. 5.8.9.1
Above Ground Horizontal Tanks Above ground horizontal tanks are mainly single-skin carbon steel within a containment bund. Some countries permit double-skin carbon steel tanks without a containment bund, providing all pipes / outlets are located at the top of the tank and approved overfill protection is fitted. Other countries insist on a containment bund, in which case there is little advantage in providing a double-skin tank. Access steps shall be provided to the tank top, no steeper than 45 degrees, and for more than one tank a second means of escape shall be provided that can be a vertical ladder with entry barrier. Tank top platforms should extend to access manholes and equipment requiring maintenance. For flowrates up to approximately 1000 litre/m, nozzle connections can be made through a tank top manhole. For flowrates in excess of this, the inlet and outlet connections should usually be made at low level through the tank end.
5.8.9.2
Underground Horizontal Tanks Underground horizontal tanks are usually double-skin carbon steel with interstitial monitoring. A single-skin carbon steel tank may be allowed in some countries, but shall be installed in secondary containment (fuelresistant membrane or concrete chamber) with a leak detection system. Glass-reinforced Plastic (GRP) tanks may be used providing they meet the specified structural loadings (including pressure and vacuum design limits) and Air BP approves the resin and tank manufacturer. As for carbon steel tanks, GRP tanks should be double-skin or within secondary containment, with interstitial monitoring. If the tank vent is to be piped to a level higher than the bridger vehicle tank to prevent possible spillage, the tank pressure rating must be able to withstand the product head plus PV valve setting. Connections to underground tanks should be in locations where they can be easily inspected e.g. through a manhole cover. A watertight access chamber should be constructed around all underground tank manholes extending to approximately 200mm above ground level, allowing sufficient space for maintenance and repairs. A cover is to required prevent rainwater ingress. See Figure 5-20. The tank manufacturer may offer a pre-fabricated steel or GRP access chamber, which is preferred to traditional building materials. This space above the manhole cover provides insulation that minimises the formation of condensation inside the tank due to ambient temperature changes.
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GROUND LEVEL TYPICALLY STEEL OR GRP SHAFT SECTION
HINGED COVER
FUEL CONTAINMENT AREA
FUEL RESISTANT GASKET BETWEEN FLANGES
FIGURE 5-20 ACCESS CHAMBER FOR AN UNDERGROUND TANK
5.8.10
General Considerations
5.8.10.1
Tank Internal Pipework Within tanks, all pipes of 50mm (2 inches) diameter or less should be of stainless steel. Above this size, pipe should be either stainless steel or carbon steel coated internally and externally with an approved lining material.
5.8.10.2
Automatic Tank Contents Gauging Where tanks are fed by pipeline, barge, ship or rail (where all the rail tank cars are off-loaded simultaneously) consideration should be given to providing an automatic tank contents gauging system meeting the requirements of the BP Measurement Standards Manual
5.8.10.3
Tank Earthing All tanks, their metal supporting structures and connecting pipelines should be effectively bonded and earthed to a standard earth electrode, and the maximum resistance to earth should not exceed 7 ohms. All earth connections should be located in positions where they can be readily inspected. Tanks should be individually earthed and not be earthed in series with each other to a single point. Paints may insulate a tank from its supporting structures and this necessitates direct earth connections from each component, or the provision of a suitable bridging arrangement, to ensure electrical continuity when another component is to act as part of the earth circuit. Where a tank bund is designed to be low-permeability, the earth rods should be installed outside the bund to obtain lower soil resistivity and avoid puncturing the bund membrane.
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5.8.10.4 Tank Signs All tanks shall be prominently numbered and clearly marked with the grade stored and provision made for the dates of the last inspection/cleaning to be added. The inlet and outlet valves shall be denoted clearly. Tank dip hatches shall display the tank number and dip reference height where applicable. Avgas tanks, and tanks which have in the past contained leaded product, shall be permanently marked with suitable signs to that effect.
5.9
STORAGE TANK INTEGRITY
5.9.1
New Tank Integrity Testing Vertical tank floor plates should be tested with a vacuum box to 0.345 bar (5 lb/sq in.) Roof plates shall be tested using soap solution / bubble test at an internal pressure of 0.005 bar ?? (0.075 lb/sq.in) Water testing should be carried out when all welding and weld dressing is completed and before the tank is internally lined. Vertical tanks shall be tested by filling with water under controlled conditions to ensure foundation failure does not occur. A record of tank settlement should be made by measuring levels at the required number of reference points equidistant around the tank circumference at regular time intervals. Levels shall relate to a fixed datum (bench mark) some distance away from the tank. Horizontal tanks are most effectively water tested in the manufacturer’s works. All tanks should be pressure tested, in accordance with the design requirements, prior to commissioning. The test pressure should be at least 1.5 ?? times the rated working pressure of the tank. Before tanks are filled with product they should be thoroughly clean and dry, and the lining fully cured.
5.9.2
Existing Tanks Apart from routine inspections of tanks for fuel quality reasons, tank internals need to be regularly inspected to confirm integrity, particularly after they have been in service for a number of years. For this reason, it is Air BP policy to carry out detailed floor inspections, including an assessment of floor plate thickness by ultra-sonic measurement on all tanks at 10 years of age, 20 years and 5 yearly intervals thereafter. (This inspection policy applies to vertical, buried and semi-buried tanks). Where a floor needs to be repaired, consideration should be given to installing a second floor if it does not already have one. Depending on the condition of the original floor, it may be repaired or alternatively covered with a membrane. The second floor is usually separated from the first by a layer of mesh or sand. Provision is be made to monitor the space between the old and new floors for signs of leakage. See Figure 5-12.
5.10
BURIED TANKS The groundwater level is critical when designing an underground tank installation. If the groundwater level can rise above the bottom of the underground tank, there is a real risk of flotation and a need for holding down. A raft type foundation to which the tanks are strapped may be necessary to ensure that the minimum 1:30 fall is maintained at all times. Where a raft foundation is constructed, it should preferably form an integral unit with the tank mounting saddles. Alternatively, a tank can be restrained against flotation by ballasting from above, combined with ground anchors if necessary – a reinforced concrete ground slab over a
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tank can also be used to locate fuelling equipment. For details, see Fig. ?? In areas with a high water table, an automatic drainage system is worth considering, such as one including small trenches between the tanks filled with gravel which leads to a clay weir drain pipe system running to a drain pit. The water in this pit is kept to the desired level by means of a float operated, electrically driven, drain pump connected to the main drain. A buried carbon steel tank shell and its fittings must be fully protected against corrosion. Tanks should always be completely surrounded by a 150 mm (6 inches) layer of clean sand material. A soil resistivity survey should be carried out to ascertain whether soil is sufficiently corrosive to necessitate cathodic protection. (For details on cathodic protection see AEG Section 11) Unless highlighted by excessive stock losses, leakage in buried tanks can occur without any evidence that it is happening. For this reason it has become standard practice in many countries to provide double containment for all buried tanks. Ways in which this can be achieved are as follows:-
5.10.1
Double Skin (Wall) Tanks With double skin tanks, the two skins are typically 5mm apart and the annular space is filled with glycol, which is kept under pressure from a header tank – one metre or so above ground level. The glycol level within the tank is regularly monitored for any drop in level which would indicate that it was caused either by the glycol leaking out through the outer skin or into the fuel compartment. Either way, a physical inspection must be carried out to establish the cause. See Figure 5-21.
HEADER TANK
GROUND LEVEL
OPTIONAL LEVEL ALARM
INTERNAL CAVITY FILLED WITH ENVIRONMENTALLY FRIENDLY MONITORING FLUID
FIGURE 5-21 DOUBLE SKIN HORIZONTAL TANK WITH MONITORING FLUID
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A variation on the above is for a probe to be installed at the bottom of the annular space without glycol so that an alarm is raised if it becomes submerged under fuel or groundwater. See Figure 5-22.
GROUND LEVEL
TO ALARM
INTERNAL CAVITY
LEAK DETECTION PROBE
FIGURE 5-22 DOUBLE SKIN HORIZONTAL TANK WITH LEAK DETECTION PROBE
5.10.2
Containment Chambers As an alternative to double skin tanks, conventional single skin tanks can be placed within a fuel-resistant membrane or concrete containment chamber and backfilled with sand. Observation wells are required so that checks can be made to ensure that there is no tank leak.
5.11
TANK BUNDS
5.11.1
Bund Capacity All above ground tankage must be completely surrounded by a bund wall. Mounded or buried tanks (double-skinned or within secondary containment) do not require to be sited in a bund but should be provided with containment for fuel overfill, commensurate with the environmental risk. Separate bunds around individual tanks are unnecessary unless required by local/national regulations. It is recommended that the total capacity of tanks in one enclosure does not exceed 60,000 m3. The bund volume should be in accordance with local regulations, or if nonexistent, the bund volume should be: •
100% of the largest tank within the bunded area, plus 10% of the volume of all the other tanks in the bund, or
•
110% of the largest tank, whichever is the greater.
The required bund volume includes the ruptured tank but excludes the volume of the bottom of the tanks within the bunded area up to the height of the bund wall. Consideration must be given to tank flotation if the bund wall is significantly higher than the tanks floor level. In calculating the
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bund volume, suitable allowance should be made for structures such as pipework and foundations that occupy significant volume. The distance between the bund wall or earth bund toe and a tank shell should preferably not be less than half the height of the tank above ground level see Figure 5-23.
EARTH BUND WALL
H
CONCRETE BUND WALL
D
D
D SHOULD BE NOT LESS THAN H/2, AND NEVER LESS THAN 2M (OR 1M FOR TANKS LESS THAN OR EQUAL TO 100M3 CAPACITY)
FIGURE 5-23 DISTANCE FROM BUND WALL OR EARTH BUND TO TANK
5.11.2
Bund Walls The height of the bund wall should preferably be kept below 1.2 metres unless space limitations prevent this, and should be constructed to meet local regulations. Bund walls should be substantially impervious to liquids (water and fuel) and designed to withstand a full hydrostatic head and the wave effect that would occur with a major tank failure. They should not normally exceed 1.2m in height to ensure fire-fighting access and good means of personnel escape. Where a number of tanks are in a large bunded area, intermediate walls of up to half the height of the main walls, or 0.6m whichever is the lower, should be provided to act as fire breaks and to divide the tanks into reasonable groups. Access to a conventional bund should be provided in the form of metal or concrete steps. At least two access points should be installed for bund walls up to 1.2 metres height, with additional steps provided for bund walls of greater height, in order to facilitate escape in the event of an emergency. Where practicable, pipes entering a bund should be routed over the bund wall rather than pass through it. Where a pipe must pass through a bund wall, the sealing of the pipe-to-wall joint should allow for typical pipe movement
5.11.3
Bund Floor Permeability Fuel spills in unlined tank bunds will penetrate the ground to a varying extent, depending on the ground type, permeability and groundwater level. To help understand, the complexity of fuel migration, see Figure 5-24 below which indicates the penetration of fuels into the ground (with a deep groundwater level) over a 24 hour period following a major spill.
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FIGURE 5-24 FUEL PENETRATION INTO GROUND AFTER MAJOR SPILL
The floor of the tank bund should be substantially impervious. On some sites, naturally occurring clay may provide an effective impermeable barrier in which case the bund floor may be finished with a layer of stone chippings laid over the underlying soil. Anything other than clay soil will, in the event of a major spill, lead to extensive contamination unless there is a high (less than 1m deep) groundwater level. In most circumstances it will be necessary to construct or install a low permeability bund floor. Two types of bund floor construction are: 5.11.3.1
Concrete floor In most cases a lightly reinforced 100mm slab should be suitable provided that the base has been adequately compacted. Special attention must be given to the design, construction and maintenance of all construction and expansion joints as well as movement joints at the bund wall and tank foundation. See Figure ??
5.11.3.2
Membrane Protected Bund Floor Membranes for this purpose should be High Density Polyethylene (HDP) or other suitable material – some have an aluminium layer for increased fuel resistance. HDP is fuel resistant and is available in roll form in various widths and thicknesses. For most purposes a 1.5mm or 2mm membrane thickness should be adequately strong. However it is necessary for the membrane to be protected by laying it on a bed of compacted sand and then by a cover of well graded fill approximately 300mm thick. Actual cover thickness will depend on overall bund design and tank foundation detail. See Figure 5-25.
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BUND LEVEL MEMBRANE SLOPING TOWARDS DRAIN
TANK BUND AREA
GRAVEL
SAND SAND
DRAIN AREA
FIGURE 5-25 MEMBRANE INSTALLATION IN A TANK BUND
Membranes are laid in strips that are welded together - each strip being approx. 10m wide. The joint welding process is the main disadvantage associated with membranes as it involves specialist equipment and an operator with a degree of expertise. For this reason it is usual to employ a specialist sub-contractor to carry out membrane welding. To be fully effective, it is necessary to lay the membrane under the entire bund area and depending on the tank foundation design, this may include under tanks. As with a concrete bund floor, it must be laid sloping to drainage channel(s) to facilitate removal of rainwater from the bund. Fixing of the membrane to bund walls, drainage channels and other obstructions such as pipe supports needs special treatment in that the membrane has to be mechanically fixed to ensure joints are liquid tight.
5.11.4
Bund Sealing Joints in concrete bund walls and floors should be filled with flexible filler board and surface sealed with a suitable flexible fuel-resistant sealant. The joint filler system and pipe penetration seals should also be reasonably fire-resistant to minimise fuel leakage from a bund in the event of a serious pool fire.
5.11.5
Bund Drainage The bund concrete slab or membrane are impervious to rainwater - it must therefore be designed with slopes to drainage channels so that rainwater can be collected and passed through an oil interceptor located outside the bund. A valve must be installed on the drain pipe where it passes through the bund wall and this must be kept locked in the closed position at all times unless it is necessary to drain off accumulated rainwater. See Figure 5-26.
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BUND SURFACE
TANK BUND AREA VALVE TO BE LOCKED CLOSED
DRAINAGE CHANNEL TO INTERCEPTOR
FIGURE 5-26 TANK BUND DRAINAGE BY GRAVITY
Where bund drainage is provided, it must pass through an oil interceptor before entering the main drainage system. An undrained bund with a pumped drainage system routed over the bund wall (to prevent natural drainage) may be necessary to comply with local regulations.
5.11.6
Buried Tanks With buried and semi-buried tanks, a thin concrete slab should be formed over the tanks around the vent, sampling and dip hatch areas. The slab should be surrounded by a kerb and be connected to drains leading to the depot oil interceptor.
5.11.7
Double Wall and Double Floor Tanks If space is limited, consideration should be given to using double wall vertical tanks where the tank contents can be contained within the secondary outer wall. As a guide, the outer wall should be approximately 70-80% of the tank shell height, and the space between the two should be not less than 1.5 metres. Valves and tank shell manholes are duplicated on inner and outer walls and access to the inner wall is via a stairway over the outer wall, although it shall be considered as a confined space for entry. Facilities to remove entrapped rainwater should be provided. See Figure 5-27.
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1.5M MIN
OUTER RING WALL TANK SHELL
OUTER TANK FLOOR
TANK BOTTOM (DOUBLE SKIN)
DRAIN
GROUND LEVEL
FIGURE 5-27 DOUBLE WALL VERTICAL TANK
5.12
VEHICLE HARDSTANDING AND MANOEUVRING AREAS
5.12.1
Design The scope of this AEG Section is to cover the design and construction of vehicle hard-standing areas. These include fuelling vehicle access, parking and loading areas within a fuel depot. Car parking areas are excluded. For a new installation the layout of the yard area shall be given careful consideration. In the first instance the area of yard constructed shall be no more than is necessary for the scale of the fuelling operation. Provision shall be allowed for future extensions of the yard area to accommodate anticipated long term growth of the fuelling operation. The preferred yard layout is such that there are two gates, one for entry and the other for exit to airside areas. The preferred traffic flow is for fueller vehicles to enter the fuel depot, fill at a loading island, then to proceed to a parking area facing the exit gate. This parking area should be located at a safe distance from: •
any hazardous area, e.g. tanks and loading/off-loading islands.
•
potential sources of ignition e.g. buildings, electrical equipment and a public boundary.
In the event of an emergency, the vehicles can be safely driven away from any hazard and out of the fuel depot. Dispenser vehicles should park in a similar, or the same, safe area. The yard area must be laid to gradients to achieve good drainage of surface water. It is important that the yard slopes away from buildings and access routes for personnel and fuelling vehicles to minimise the risk from fuel / fire spread in the event of a spillage. Vehicle loading/off-loading stands should be level but dished towards the centre to collect possible
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spillage. At the lowest point of the yard a containment area with outlet drain valve can be established, by means of raised kerbs or otherwise, to act as emergency containment in the event of a major spillage, e.g. a fueller tank rupture. Pavement construction shall be 'flexible' and low permeability. The materials of construction can be concrete block paving (200 x 100 x 80mm thick, interlocked) or reinforced concrete slab or fuel-resistant blacktop. Conventional blacktop (asphalt or macadam) construction is generally unsuitable for fuel depot yard areas because it is affected by fuel spillage, although it may be used for "clean" access roads where fuel spillage is unlikely to occur. The pavement design shall take into account the number and axle weights of the vehicles used for the fuelling operation fueller axle weights are more critical because the loads are much heavier than for dispenser vehicles. The pavement thickness also depends upon the underlying ground conditions. The site investigation should reveal the safe bearing capacity and groundwater level. In colder climates the pavement depth may have to be increased to avoid frost damage to the underlying sub-grade. A typical construction for concrete block paving could be: 80mm 50mm 300mm 170mm
600mm
Concrete blocks Sand Lean mix Subbase TOTAL
A typical construction for reinforced concrete slab could be: 200mm 400mm
double-reinforced concrete (air-entrained if necessary) sub-base
600mm
TOTAL
With both the above types of pavement construction a geo-textile separation membrane can be used under the sub-base where the subgrade is a low strength material. In specific areas of heavy traffic, e.g. entrance and exit routes and at islands, the pavement thickness can be increased. The pavement design standards to be used shall be those applicable to the location.
5.12.2
Materials The choice of materials to be used in the pavement construction depends upon local costs, construction resources and labour skills. Conventional blacktop materials could be used for entrance roads, exit roads and car parks but not for areas where fuelling vehicles are parked.
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Concrete block paving is a popular material for fuel depot yards. The advantages are as follows: •
Costs same or less than reinforced concrete slab
•
Materials readily available for most locations
•
Requires only semi-skilled labour
•
Can be excavated and reinstated easier than RC slab
•
Quality control relatively simple
•
No expansion joints (subject to the provision of adequate edge restraint) therefore no joint maintenance
•
Minor level adjustments possible Reinforced concrete slabs require skilled labour for installation, contain expansion joints, which require ongoing maintenance and do not allow easy excavation and reinstatement. The repair of long-term surface deterioration is difficult and not always successful.
5.12.3
Environmental Considerations As previously stated, the running surface must be relatively impermeable to both water and fuel. A typical low permeability requirement is 10-8 cm/s. Concrete block paving, although containing joints between the blocks, are considered by most authorities to become adequately impermeable after a period of use. The joints are filled initially with fine sand but in time become sealed by dirt and detritus. It is recommended that new concrete block paving should be sealed with a clear fuel resistant sealer – this acts as a binder for the interlocking sand and reduces permeability. Joints in RC slab construction are sealed with a flexible fuel-resistant sealant but their effectiveness is dependent upon the sealant being well maintained. Experience has shown that, unless properly selected and installed, the effective life of such sealants can be relatively short. The pavement permeability is especially critical at areas where fuel is handled, e.g. vehicle loading/off-loading stands and PCV test rig stands. These stands shall preferably be of RC slab construction with the minimum of expansion/contraction joints and drainage direct to either a catchment tank or oil interceptor. Reference should be made to local and national oil industry design regulations.
5.13
ACCESS AND SECURITY (LANDSIDE AND AIRSIDE)
5.13.1
Perimeter Protection The perimeter of the installation should have a fence or wall that meets the requirements of local licensing and planning authorities and which will provide a deterrent against intruders. Any wall or gate forming part of the perimeter should provide an equivalent level of security. There should be no cover for an intruder on either side of the fence, either from vegetation or large items of stores/equipment. A clear strip 2m wide on both sides of the fence is desirable. Where vulnerable equipment, stores or plant are close to the perimeter, the space between them shall be well illuminated at night. The whole of the perimeter shall be easily approached from inside the site.
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5.13.2
Control of Access Wherever possible, the cars of staff, visitors and contractors should be parked outside the depot security fence, preferably ‘landside’.
5.14
PRODUCT RECEIPT FACILITIES The design of reception facilities will vary significantly according to the method of fuel supply. However in all but the smallest locations and irrespective of method of supply, systems should be provided to shut off flow into storage in the event of an emergency situation arising or to prevent a tank overfill. Closed sampling and product recovery systems should be considered for all product receipt facilities. Spillage containment is essential for all product receipt installations, commensurate with the risk of damage to the environment e.g. product loss to water. Electrical bonding requirements are discussed in AEG Section 11. Other points to note in relation to the various product receipt methods are discussed below.
5.14.1
Pipeline Receipt Where the volume of fuel handled by an airport installation is sufficiently high, supply by pipeline is likely to be the most efficient and cost effective method. The space required for reception facilities will be relatively small provided the pipeline is dedicated to Jet A-1. If this is not the case, then reception tanks will be necessary. Pipeline receipt facilities will normally consist of the following elements pipeline isolation, reception for pipeline cleaning devices (pigs), pressure control, filtration, metering, product off takes and pipeline service tank. See Figure 5-28 An example of a fuel receipt facility
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DOUBLE BLOCK AND BLEED VALVE
METER PROVING CONNECTION
PIG TRAP
STRAINER PRESSURE RELIEF
DOUBLE BLOCK AND BLEED VALVE
FILTER SEPARATOR
RECOVERY TANK METER DRAIN TANK
DOUBLE BLOCK AND BLEED VALVE
TO MAIN SURGE
FIGURE 5-28 AN EXAMPLE OF A FUEL RECEIPT FACILITY
5.14.1.1
Isolation Pipeline isolation from the fuel depot is essential, as the pipeline is often under different operator control. Pipeline block valves used for this purpose should be of 'double block and bleed' capability so that positive isolation can be achieved. As with all other valves in the depot, they should be ‘firesafe’. They may also need to be full-bore type to allow the passage of pigs. If the valves are fitted with actuators then it is important that the valve closure time must be such that excessive surge pressures are not generated.
5.14.1.2
Pig (Pipeline Cleaning Device) Receipt Pig receipt facilities should be provided to cater with the inevitable need to clean or empty a pipeline. The main item is a receiver or "trap" which, together with associated pipe-work, should allow for by-pass, drain down and refill of the trap so that the pig can easily be removed. The trap must be fitted with an air vent, drain point and isolation valves. The pig trap closure shall be fitted with a mechanical interlock to ensure that the pressure inside has been vented before the door can be opened. Additional consideration is required for ‘intelligent pigs’ which require a longer pig trap. Because pigging can be infrequent, sometimes pig traps are fitted only when required, but space and valve provision are essential.
5.14.1.3
Filtration At least two sets (or banks) of filters should normally be provided so that if one set has to be shut down, flow can be switched without interrupting the product receipt. Each filter set will frequently consist of three stages of filtration - strainers to remove coarse debris, pre-filtration where desirable, and filter/water separators.
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5.14.1.4
Pressure Relief The need to relieve excess pressures will arise as a result of high (> Class 150) pipeline operating pressure, build up of thermal pressure or the generation of surge pressure due to valve closure or possibly filter monitor shutdown. Appropriate relief valves and facilities must be provided.
5.14.1.5
Metering Metering of incoming product is mainly required for pipeline loss control purposes where the incoming quantity is continuously compared with a meter at the start of the pipeline - any difference initiates an alarm indicating that there may be a leak. Stock transfer is, of course, another application but it can also be carried out by tank dips.
5.14.1.6
Product Off-Takes Some of the above functions require product to be taken out of the main pipe-work and diverted into separate storage. Examples of this are product arising from relief valves lifting or during receipt of a pig. A pipeline service tank should therefore be provided with sampling facilities and a pump to re-inject into main storage or despatch slops off-site.
5.14.1.7
SCADA The pipeline shall be capable of start-up only when an ‘enable’ signal is available from the receiving depot. Automatic shutdown of the pipeline in the event of a tank high-high level, or if a emergency stop button is activated should be implemented. Information on the total flow rate and volume of fuel received during a transfer should be displayed (especially if from more than one source at the same time).
5.14.2
Ship/Barge Jetty Offloading Berthing arrangements for ships are outside the scope of AEG. Other comments follow.
5.14.2.1
Marine Discharge Arm The connection between ship's discharge manifold and the jetty pipeline must be sufficiently flexible, to accommodate the movements of the ship brought about by unloading, tidal changes and currents. At low throughput locations, offloading through hoses may be suitable but hoses larger than 100mm in diameter are difficult to handle and require frequent adjustment throughout discharge. Hoses are also more prone to spillage. Marine discharge arms are therefore preferable where justified by throughput or manpower limitations.
5.14.2.2
Jetty to Depot Pipeline The transfer of product from ship to depot storage is normally carried out using the ship's own pumps. The pipeline between jetty and depot should be dedicated and designed to suit maximum offloading duties of ships’ pumps. Depending on length, isolation valves should be strategically located along the pipeline. A non-return valve should be provided at the jetty end to prevent product flowing back into the ship. Consideration should be given to possible surge pressure generation should any shore valve be closed either deliberately, accidentally or automatically by a control system. Facilities to drain down the marine discharge arm and ship's line should be provided. A closed sampling and product recovery system at the jetty should be considered together with environmental provisions to prevent spillage to water.
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5.14.2.3
Reception Storage Unless it can confidently be expected that all ships delivering product are totally dedicated, separate reception storage will be necessary. This is to ensure that there is no possibility of untested fuel being allowed to enter operational storage. Reception tanks should be sized to accommodate the maximum likely cargo load. With barge fed depots, separate Reception storage may not be required provided the barges and shore facilities are dedicated.
5.14.2.4
Reception Filtration The degree of reception filtration required depends on whether or not the fuel is supplied in dedicated ships and whether or not it is received direct into airport storage tanks. Strainers are recommended in all cases. Product supplied in dedicated ships to airport storage should pass through filter/water separators. The need for micro-filters may also be justified. With undedicated supply to non-airport tanks, there is little merit in installing filter/water separators.
5.14.3
Road Tanker (Bridger) Offloading Road deliveries are made frequently by personnel and equipment outside the direct control of the airport fuel depot operator. It is therefore desirable that offloading facilities should be sited as far as possible away from other operational areas but still within sight of the control room. Reception facilities for Jet fuels and Avgas should be segregated to the maximum degree possible. Where practical, selective hose connections shall be used for differing fuel grades. Air BP prefers an island type layout for offloading stands enabling two road tankers to park, one either side of the island. Each island is designed to accommodate two pumps, one pump for each side of the island. With this arrangement, pumps are located as close as possible to the offloading hoses to minimise suction problems associated with an air slug being drawn into the offloading system as the vehicle empties. With a single 100mm hose and suitable pump, bridgers can be offloaded at a flow-rate of approximately 140 (or 100) ??m3/hr provided that they are fitted with a 100mm outlet coupling. Filtration and other equipment can be remotely located. The advantage of this arrangement is that as pump suction pipework is minimised, simple centrifugal pumps can be used. It also reduces the risk of operators leaving the pumps running after offloading is complete. See Figure 5-29 Example of a bridger off loading island. The number of offloading islands/stands will depend on the estimated frequency of delivery and the need to avoid long delays for vehicles waiting to unload. Provision should be made for future offloading islands.
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PUMP
PUMP
6" N.B.
COUPLING SIGHT GLASS HOSE
FIGURE 5-29 EXAMPLE OF A BRIDGER OFF LOADING ISLAND
5.14.4
Rail Car Tanker Offloading Train sizes vary but typically in Europe, a basic block train may comprise of either twenty cars of 45 tons gross weight or ten of 100 tons gross weight, carrying a total of about 30 and 75 tons of Jet fuel respectively. The facilities should be suitable for discharging both the 45 and 100-ton rail cars. For each rail car, a separate offloading hose, complete with coupling and isolating valve and sight glass should be provided. Facilities for sampling each rail car must be provided close at hand – this can be a fixed system or a mobile sampling trolley. The number and spacing of offloading hose connections will depend on the length of each rail car and the number making up a complete train. Where space is at a premium, it may be only be possible to provide half the number of offloading points in which case it will be necessary to move the train when the first half is empty. See Figure 5-30 A depot supplied by rail. Rail car offloading pumps will normally need to be located at some distance from the siding and will therefore need to be capable of handling difficult suction conditions including frequent air slugs as rail cars empty. Associated reception filtration should preferably be located in an area close to tanks. It is likely that a separate drainage system will be necessary to cater for the rail siding. Where possible rail sidings should be located outside the normal depot operational area. Environmental protection measures comparable with the fuel depot should be in place, including low-permeability surfacing and spill containment.
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RAILWAY TRACK
OFF LOADING PUMPS
STORAGE AREA OFF LOADING POINTS
PLANNED PARKING
LOADING PUMPS
FUELLER LOADING ISLANDS
ADMINISTRATIVE AND SERVICE BUILDINGS
FIGURE 5-30 A DEPOT SUPPLIED BY RAIL
5.15
FUELLER LOADING
5.15.1
General Loading facilities should be designed with a view to obtaining high fueller utilisation, particularly during periods of peak airport activity. Waiting and loading time should be minimised by the provision of an adequate number of loading stands with pumping performance to suit. The number of individual loading stands will depend on the size of the fueller fleet, the loading rate capability, the pattern of peak aircraft fuelling activity, type of aircraft etc. Loading rates should be in the range of 100 140 m3/hr. In recently designed facilities, Air BP has standardised on an arrangement whereby fuellers park either side of a loading island (each island caters for two fuellers). See Figure ??. Equipment on the island is limited to flow control valves, meters, quick acting manual shut-off valve, bottom loading hoses with dry break couplings and sampling facilities. Pumps and filter/water separators are remotely located.
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THERMAL RELIEF
METER AND FLOW CONTROL VALVE
2 1/2" AIRCRAFT FUELLING HOSES AND COUPLINGS
4" BALL VALVE
FIGURE 5-31 STANDARD FUELLER DEPOT LOADING ISLAND
At airports with fuel hydrant systems where a feed can be taken to load fuellers, a similar island arrangement is used but with the added precautions of a positive isolation valve (double block and bleed type) and a pressure regulating valve to limit pressure on the discharge side to 2 - 3 bar. Loading hoses should be of a type approved for aviation use. Where more than one grade of fuel is loaded, couplings shall be grade selective. A pump emergency shut-off button shall be easily accessible from each loading stand / island.
5.15.2
Basic Requirements All product pipe-work and fittings downstream of the loading filtration equipment shall be of stainless steel, or of mild steel with an approved lining material (see Air BP Technical Approvals). All fueller loading facilities shall be constructed for use by the bottom loading method, through self-sealing product selective couplings. In general, it should be possible to load a fueller at approximately the same rate at which it is capable of delivering its cargo. The number of individual loading stands required at a particular airport depot will depend on the size of the fueller fleet, the loading rate capability of the loading facilities, the pattern of peak aircraft fuelling activity at the airport (duration of peaks, number and type of aircraft, frequency of arrival etc.), the distance between the depot and apron, along with other factors. No two sets of circumstances will be the same, although an attempt has been made in Figure 5-32 Fueller and loading island requirements to give an idea of the range in numbers of loading bays and fuellers required. For less than 6 minutes between arrivals of aircraft, a hydrant system will often be more cost efficient. Generally it should be possible to simultaneously load at maximum rate one-third to one-half of the fuelling fleet.
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TIME BETWEEN AIRCRAFT ARRIVALS
LOADING BAYS
FUELLERS
10 8 6 4 2 0 0
10
20
30
40
50
NUMBER OF LOADING BAYS / FUELLERS REQUIRED
FIGURE 5-32 FUELLER AND LOADING ISLAND REQUIREMENTS
The loading facilities of different grades of fuel should, where practicable, be physically separated, such that the loading hoses of one grade will not reach vehicles parked at the loading points for other grades. Facility design should permit filling of the largest fuelling vehicle including trailer without the necessity to move them during the filling operation.
5.15.3
Equipment Where fuellers are loaded through meters, and several meters are served by one pump, it is necessary to install flow-rate limiters in each line to prevent overrating the meters. Meters with a pre-set volume capability enable the operator to programme a load volume rather than rely on the fueller vehicle’s high-level shut-off. The speed with which fuel flow is stopped when loading by the bottom loading method is dependent on the equipment mounted on the island and within the fueller. This is invariably designed for slow, or two stage, closure and hence specific surge pressure protection should not be necessary on loading facilities, other than in exceptional circumstances of very long, small bore systems. Weatherproof hose stowage boxes should be provided at loading (and offloading) points, clearly marked with the appropriate grade identification as given in the Air BP Regulations. On "island" facilities, hoses should serve either side as required. A quick acting manual shut-off valve should be located in the loading pipework, immediately upstream of the loading hose. Each fueller loading point should be equipped with a flexible bonding cable, having one end securely and positively attached to a common earthing point. The free end of each bonding cable should be fitted with a spring-loaded clip for attachment to a vehicle. All fueller-loading facilities shall be provided with an emergency stop valve to isolate the tank from the fueller loading in an emergency situation. This
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valve should automatically move to the closed position when an associated emergency stop button (ESB) is activated. A ‘pump running warning light’ should be considered where a manually controlled fueller loading pump is remote from the loading stand, to warn the operator that the pump is running after loading is completed. It should be noted that many fuellers might have vents that are too small to handle over-flowing fuel at the normal loading rate. It may be advisable to install hose-end pressure controllers in the loading hoses to minimise the possibility of rupturing a vehicle tank should the Hi-level shut-off fail.
5.16
FUELLER DEFUELLING A fueller vehicle may self-discharge on-specification fuel into the main storage tanks via. a PCV test rig. If de-fuelled aircraft product is to be stored, it shall be discharged from the fueller into segregated storage via. a dedicated inlet line fitted with an aircraft coupling. Provision should be made for returning the fuel to the fueller (and to the customer) or to main storage subject to fuel quality testing.
5.17
FUELLER & DISPENSER TEST FACILITIES A vehicle PCV test rig enables fuellers and dispensers to simulate conditions encountered during aircraft fuelling. This simulation is necessary to carry out hose end pressure control tests and hose end contamination (Millipore) tests. The test rig can be used for maintenance purposes such as meter proving and also for staff training. The main equipment on a test rig consists of aircraft couplings to connect the fuelling vehicle hose end couplings, sampling connections, pressure gauge(s), quick acting ball valve, and gate valve. The pipe between the aircraft couplings and the sample (Millipore) connection should be stainless steel or lined carbon steel. See Figure 5-33.
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PRESSURE GAUGE
MILLIPORE TEST POINT
BALL VALVE
HIGH LEVEL TEST POINT
4" N.B. PIPE
2x 221" COUPLINGS
CROSS BRACING CROSS BRACING PRESSURE GAUGE
FUELLER
MILLIPORE TEST POINT CONCRETE LEVEL
ROAD ELEVATION
LOW LEVEL TEST POINT WITH 2x 221" COUPLINGS
FIGURE 5-33 MAIN EQUIPMENT ON A TEST RIG
One aircraft coupling should be provided for each hose on a vehicle. The layout of the test rig and the number of couplings will depend on whether the vehicles to be tested have hose reels only, or hose reels plus deck hoses. With deck hoses, it is recommended that the test rig couplings be installed at high level unless there is provision for the deck hoses to divert to a low-level test rig. In the case of fuellers, fuel is pumped back to storage and so it is therefore necessary to connect the discharge from the test rig to the tank inlet manifold. It is not necessary for this fuel to pass through depot filtration since it is into-aircraft quality. It is recommended that a pilot operated solenoid valve is installed in the pipeline to the receiving tank so that in the event of a tank high level alarm situation developing, flow from the test rig can be automatically shut off. The test rig should be reasonably close to the receiving tank and the pipework should be designed to minimise backpressure - if the receiving tank is too high (or near full) or elevated relative to the test rig, the back pressure may be too high to achieve a successful test. High back-pressure causes the dispenser PCV system to act, thereby restricting flow. A design back-pressure at maximum flowrate of 3.5 bar at the coupling is recommended – as for aircraft fuel system design. For dispensers, a connection from the hydrant delivery pipeline is necessary and this should terminate in a hydrant pit valve set into the ground. This allows the dispenser to circulate from tank back to tank. It is important that the pipe-work is arranged so that dispensers can circulate back to a different tank than that on hydrant duty. An emergency shut off button should be provided so that hydrant pumps can be stopped in the event of an emergency. See Figure 5-34.
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Fuel hydrant emergency stop
FIGURE 5-34 FUEL HYDRANT EMERGENCY STOP BUTTON SIGN
At busy airports with large fuelling fleets, it may be necessary to provide more than one test rig. The layout of the test should enable all hoses to be conveniently connected. Vehicle access to and from the test rig should be such that reversing is unnecessary.
5.18
GAS OIL DISPENSING (COC) FACILITIES The fuelling vehicles will require a fuel facility for their own use (Company’s Own Consumption). If not available elsewhere on an airport, this may be located in the storage depot or forward fuelling depot. The facility shall comply with local, national and industry regulations. There is no special aviation engineering requirement but the fuelling vehicles must be studied regarding the location of the fuel tanks and turning circles to access the COC pump. The kerbside pump may be located at a bridger offloading stand, fueller loading stand or vehicle washbay to make use of environmental protection measures already in place. The gas oil tank is sometimes within a Vehicle Service Building and used also for building heating.
5.19
PIPEWORK, FITTINGS AND VALVES In specifying pipe, fittings and valves, reference should be made to relevant Air BP and BP Group documentation. See also AEG Section 6 for details on materials and coatings for pipe-work.
5.19.1
General Arrangement Figure 5-35 Basic piping layout for a single grade fueller depot - shows the basic piping layout and flow path for a single grade fueller depot. If more than one grade of fuel is supplied, each grade must have its own independent piping and tankage. The depot pipework should be designed in stages: •
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A basic flow diagram is used to illustrate the means of fuel supply, storage and receipt.
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•
A process and instrumentation diagram (P&I Diagram) is developed to show all elements of the system, mechanical and electrical.
•
Detailed piping drawings may then be produced – these are sometimes done by the supplier with reviews at stages.
At each stage, some form of review and approval is necessary to provide technical assurance, avoid mistakes and achieve maximum value. The piping design shall be checked against the design brief (Statement of Requirements) and the modes of operation specified by the operator to ensure that all operator functions are provided for. The P&I Diagram should be subjected to a HAZOP study where the proposal is major, novel or a change to an existing system.
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BRIDGER OFF LOADING COUPLINGS
TANK
TANK
FILTER WATER SEPARATOR
FUELLER LOADING COUPLINGS
FILTER WATER SEPARATOR
FIGURE 5-35 BASIC PIPING LAYOUT FOR A SINGLE GRADE FUELLER DEPOT
5.19.2
Non-return Valves (NRVs) Non-return valves should be provided where there is a need to prevent reverse flow, possible leading to product spillage, but they must not be considered to be totally reliable or failsafe. One application in aviation fuel depots is to prevent inadvertent tank transfers, especially where tank roofs are at different elevations, by installing non-return valves in tank inlet and outlet lines (and any other tank connection lines e.g. drain and sampling pipes). It should be possible to override each non-return valve by manually setting it to the open position. Care should be taken in selecting non-return valves for the tank outlet line to ensure it does not cause an unacceptable pressure drop in the pump suction line.
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Where a NRV failure could result in a spill, a secondary alarm and shutdown system should be considered.
5.19.3
Buried Depot Fuel Pipes Buried fuel pipes are potential sources of leakage and should therefore be avoided if possible. Where impractical, the carbon steel pipe should be well protected externally (factory-applied or double-wrapped at site) and cathodically protected. Alternatively, Grade316L stainless steel pipe protected externally (factoryapplied or double-wrapped at site) without cathodic protection may be used. Glass-reinforced Plastic (GRP) pipe or ?? UPP may be used providing it meets the specified structural loadings (including pressure and vacuum design limits) and Air BP approves the resin/plastic and pipe manufacturer. As for carbon steel pipe, GRP and UPP pipe should be double-skin or within secondary containment, with interstitial monitoring. Flanges should be installed before and after pipes leave the ground and test connections at one end, to facilitate pressure testing. Short sections of buried pipe (up to around 20m) e.g. across a road or under a yard to a loading island should be laid within a containment membrane and incorporate a tell-tale monitoring system such as the example in Figure 5-36.
GROUND LEVEL IMPERVIOUS MEMBRANE
FALL
PERFORATED PIPE SEALED PIPE INSPECTION PIT (WATER TIGHT CONSTRUCTION) OR MONITORING WELL
FIGURE 5-36 EXAMPLE OF A BURIED PIPE WITHIN A CONTAINMENT MEMBRANE
Two other acceptable methods are: •
A low permeability open duct with removable covers to enable inspection of the pipe, and a monitoring point at one end. A means of removing rainwater may be required.
•
A double-skin pipe with monitoring of the sealed interstitial space
Further details can be provided by Air BP Technical.
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For longer (cross-country, inter-depot or feeder) pipelines, an automatic leak detection system should also be provided. Wherever practicable, all pipelines should be designed to accommodate cleaning or 'intelligent' pigs. Long pipelines and pipes under roads should be provided with a low point drain to enable removal of accumulated water. AEG Section 6 covers pipe wrapping and cathodic protection.
5.19.4
Hose Couplings All fueller-loading hoses should be fitted with dry-break couplings. Where possible, depot-offloading hoses should also be fitted with dry-break couplings. If this is not possible, then facilities for draining hoses should be provided at each offloading stand. Care should be taken to ensure that the use of dry-break couplings does not lead to a thermal pressure problem – a relief system may be required to deal with liquid or air/vapour pressure build-up in hoses and pipework.
5.20
SAMPLING AND PRODUCT RECOVERY SYSTEMS
5.20.1
Background During its journey from a refinery to aircraft, small quantities of contaminants - water or particulates - may enter the product from the air or from the facilities themselves. Aviation fuelling facilities shall be designed to minimise any inbuilt source of contamination, and to ensure that where contamination does occur it can be effectively collected and removed by settling, filtration and draining. An essential part of normal operating practice is to ensure product quality is maintained by drawing and examining samples of product from designated points and at regular intervals. The samples are examined visually and with water-detecting apparatus to check if contaminants have entered the product or the effectiveness of the methods used to remove them. Traditionally samples have been taken from tanks, filters and piping through a small bore drain line from a sump or low point in the item of equipment. Product is flushed into an open top sampling container, usually a glass jar or stainless steel bucket, to allow the operator to examine the product visually or with water detection chemicals. To be representative, the product contained in the drain line must first be expelled so that the sample taken comes from the sump or low point in question. Contaminants will tend to settle in a sump and it is necessary to obtain a high flowrate to wash these out through the drain line as part of the sample. Samples are therefore taken at 'full flush', with a valve at the end of the drain line being opened fully for a short time.
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However, there are a number of drawbacks to this approach. There is a risk that the sample may not be truly representative if the content of the drain line is not first expelled or the flow is not fast enough to entrain particulates or water. There is a risk of product being spilled, or splashing the operator, as it enters an open sampling container. If the sampling container is not scrupulously clean or if particulates or water enter the sample from outside, the resulting examination will be misleading. The quantity of product removed from the drain line, the sample itself and any product that is subsequently flushed to clean the sump must all be disposed of.
5.20.2
Closed Sampling To address these issues, Air BP introduced the concept of ‘closed sampling’ in the early 1980's. The objective was to be able to visually examine jet fuel in a satisfactory manner to ensure the integrity of quality control measures whilst also minimising: •
The amount of product downgraded during sampling processes
•
Time spent on the task
•
Risk of small spillages
•
Operator exposure to product.
Closed sampling is now widely used in aviation fuel depots and on hydrant dispenser vehicles, so that the practice of taking samples in open buckets and glass jars is completely eliminated for all normal operations. Also the quantity of product downgraded to slops is greatly reduced and its collection centralised. The basis of this method is a piping circuit incorporating a 'sampling station' and intermediate product collection and recovery tanks through which samples of product taken from filters, tanks or vehicles can be examined, water and dirt removed and clean product eventually returned into storage. The volume combined in water draw-off lines plays an important part in the efficiency of routine sampling for water from vertical tanks. A sample return tank of typically at least 200 litres capacity should be provided to enable contents of the draw-off line to be captured and to allow fast flushing without danger of splashing or spillage. Examples of product recovery tanks can be supplied by Air BP Centre Engineering. A tanks closed sampling loop is shown in Figure 5-37.
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TANK WATER DRAW-OFF LINE
PRODUCT RETURNED TO TANK
TANK'S CLOSED SAMPLING STATION FILTER/WATER SEPARATOR
MAIN PRODUCT RECOVERY TANK
RETURN PUMP WASTE OIL/ WATER TANK
FIGURE 5-37 TYPICAL TANK CLOSED SAMPLING / PRODUCT RETURN SYSTEM
All sampling points should preferably be connected to an approved closed sampling system but manual sampling points are still necessary for secondary checks or back-up. Manual sampling points shall permit the unhindered drawing of a sample into an approved sampling bucket or glass jar which requires a clear space of approximately 350 mm (14 inches) below the sampling line outlet, see Figure 5-38.
FROM PIPEWORK
SAMPLING POINT
350MM
CAP
FIGURE 5-38 PROVISION OF ADEQUATE SPACE BELOW A MANUAL SAMPLING POINT
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At depots where there is a frequent need to remove large quantities of water from storage tanks (e.g. following discharges by coastal tankers), it is recommended that a larger (20-50m3) capacity product recovery tank (PRT) is installed. The PRT should be internally lined, sloped to a sump and fitted with a high level alarm. Using suitable piping and valved manifold(s) the PRT should be able to collect product from each of the main tanks and, after settling and testing, clean product should returned (through filtration) to the main tanks. Fig ?? depot block diagram shows a typical depot incorporating such a sampling circuit. Product is flushed from the sumps of the reception filters, bridger offloading, storage tanks and into-hydrant / fueller loading filters into adjacent 'sampling stations' (1, 2, 3, 4, & 5) where the product can be examined by an operator. Each sampling station consists of a small 'side tank', a special glass closed sample jar or 'sampler' and interconnecting piping and valves. All of the sampling stations are used in a similar way. To illustrate how they are used, consider the sampling station (1), adjacent to the storage tank, as shown in detail in Figure 5-39 VENT FROM COLLECTION TANK WATER TEST POINT TANK SIGHT GLASS
CLOSED SAMPLER
SEALED SITE TANK
STAINLESS STEEL PIPE
SPRING CLOSED VALVE
SUMP
GLASS TEE
TO COLLECTION TANK
FIGURE 5-39 CLOSED SAMPLING STATION ADJACENT TO STORAGE TANK
Samples of product are flushed from the tank centre sump through a stainless steel line via a spring-loaded ball valve and a glass tee to a side tank. The glass tee is used for two reasons. Firstly, the operator can observe the clarity or otherwise of the product as it flows into the side tank and thus immediately has an indication of the condition of the sample. Secondly, when the product in the side tank has settled, the operator can see whether water or dirt is present and can base his future actions on this observation without actually having to take a sample from the bottom of the side tank.
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In this case the side tank is a completely closed vessel, with a line to the top of the main tank to prevent an overflow. A sight glass is incorporated in the vent line to let the operator know when the side tank is full. Similarly, the associated sampler is a sealed unit vented to the top of the main tank. The capacity of the side tank is chosen so that when it is full the contents of the drain line and the tank sump will have been completely flushed into the side tank. This is to ensure that the sampling process will be carried out on a truly representative sample of product from the tank sump. After sampling, product drains by gravity from the sealed side tank into a semi-buried product collection tank. Figure 5-40 shows a typical product collection tank. It is fully automatic in operation - product flows in, a high level switch starts an associated transfer pump and a low level switch stops it again. It cannot overflow as the tank is sealed and vented into the top of the main storage. Suction is from the outlet of a steep conically shaped bottom so water or dirt should not accumulate.
STAINLESS STEEL HANDLES STAINLESS STEEL TANK BODY
INLET PIPE
OUTLET PIPE
FIGURE 5-40 A TYPICAL 100-200 LITRE PRODUCT COLLECTION TANK
In larger depots, more than one product collection tank may be required and these really are just a means of collecting the samples from several side tanks in an immediate area and passing the product on to a central product recovery tank - no sampling is carried out at the collection tanks themselves. Product from the collection tanks is pumped into an above ground central recovery tank, as shown in Figure 5-41. When the product recovery tank is full it is allowed to settle and then the content of the sump is flushed into an adjacent sampling station.
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After confirming that the quality of the product in the recovery tank is satisfactory, the fuel is pumped back through filtration into storage. All water and dirt extracted from the product recovery tank at the sampling station is dropped under gravity into a buried waste oil tank. Periodically a waste oil contractor using a suction tanker takes the contents of the waste oil tank off-site.
HIGH HIGH LEVEL ALARM HIGH LEVEL ALARM
SAMPLE TANK
SAMPLER
TO STORAGE ABOVE GROUND PRODUCT RECOVERY TANK FROM PRODUCT COLLECTION TANK
GLASS TEE
HIGH LEVEL SWITCH SUCTION TANKER CONNECTION PUMP MOTORISED VALVE
BURIED WASTE OIL TANK (DOUBLE SKINNED)
FIGURE 5-41 TYPICAL LARGE FUEL DEPOT PRODUCT RECOVERY PROCESS
The principal virtues of this arrangement is that it is quick and easy to use, there is no manual sampling or exposure to product at all, there is no waiting around for the side tank to settle and no need for local pumps to return the sampled product back into the main tank. Figure 5-42 shows the sampling station (4) for the into-hydrant filter/water separators but the same principle is also used for the upstream filters at pipeline reception (3).
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FILTER WATER SEPARATOR
FILTER WATER SEPARATOR
FILTER WATER SEPARATOR
STAINLESS STEEL TUBING
DRAIN HOSE
SAMPLER SAMPLE TANK
SAMPLING STATION
TO COLLECTION TANK GLASS TEE
FIGURE 5-42 INTO-HYDRANT FILTERS CLOSED SAMPLING SYSTEM
The sump of each filter/water separator is piped to the sampling station using small bore stainless steel tubing and the valving arrangement allows a sample from each sump to be drawn in turn into the sampler. The tubing diameter and length are chosen to ensure that the contents of the sampler give a true representation of the condition in the sump. The glass tee enables this operation to be monitored as the fuel flowing into the side tank can be inspected visually. Filter/water separators need to be drained for maintenance – this may be done using the closed sampling system. At the conclusion of the sampling operation the contents of the sample tank are dumped by gravity into a semi buried collection tank and hence pumped automatically to the above ground product recovery tank for separation/recovery. Overfill protection in this instance is by spring loaded ball valves only, as typically the location of such filter vessels is too far from the main storage tanks to justify completely closing the system. Figure 5-43 shows a typical bridger offloading sampling arrangement (5). This allows product to be flushed from the base of the bridger through the offloading hoses into the sample tank and then sample the actual incoming fuel. As before, a glass tee allows both observation of the flow stream plus an assessment, after a few moments settling, of the quality of the fuel in the tank.
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BRIDGER OFF LOADING
TO STORAGE
SAMPLER
SAMPLE TANK
GLASS TEE
TO COLLECTION TANK
FIGURE 5-43 TYPICAL BRIDGER OFFLOADING SAMPLING ARRANGEMENT
Again the content of the side tank is dumped by gravity to a semi-buried collection tank and hence pumped to the product recovery tank. Details of typical closed sampling equipment, side and product recovery tanks are given in MECH 90 it doesn’t exist any more.
5.20.3
Design and Layout Notes Closed sampling systems are usually low pressure (
