Pipeline Engineering Training Manual
NATIONAL ENGINEERING AND TECH. CO. LTD (NETCO)
PIPELINE ENGINEERING TRAINING MANUAL
TABLE OF CONTENTS 1.0
CODES AND STANDARDS
PIPELINE ENGINEERING DELIVERABLES
INPUT TO PROPOSALS
INTERFACE WITH OTHERS
OTHER ENGINEERING DISCIPLINES
UNIT CONVERSION FACTORS
OBJECTIVE This pipeline engineering discipline training manual is intended to provide information about pipeline engineering and to list design deliverables produced by the discipline. It also includes guide to the pipeline engineer on the methodology and basic approach/work process towards producing the deliverables. Furthermore, it x-rays the work interface with other engineering disciplines and departments in NETCO with respect to the pipeline engineer’s responsibility on a project. It is however not intended to be a design manual.
INTRODUCTION A pipeline is the means of conveying fluid from one location to another or generally from source to user. There are three major groups of oil and gas pipelines namely: Gathering, Transmission / Trunk and Distribution pipelines. Gathering pipelines connect individual oil/gas sources to central treating or processing facilities. Transmission pipelines refer to pipelines that transport gas, crude oil or refined products. Flowlines are relatively small diameter pipelines that convey untreated oil/gas to a central facility for processing. Distribution pipelines are mostly applicable to gas transportation where they are used in a network to convey gas from utility companies to end-users. Pipeline engineering involves the scientific task of designing, constructing, operating and maintaining pipeline systems. The pipeline engineer should decide on which specific pipeline installations (materials and otherwise) are suitable for transporting the fluid involved. In deciding this, the pipeline engineer utilizes some codes and standards and recommended practices to ensure a safe pipeline system. Note that pipeline involves fluid transportation off-plot (outside the plant area) in contrast to piping which relates to the pipework in and around the plant area or facility. This training manual presents aspects of pipeline engineering relating to the design of a pipeline.
A tubular material used to convey variety of liquids, gases and solids over distances that range from a few metres to hundreds of kilometres.
A small diameter pipeline transporting untreated fluids from one or more wells to a gathering center, generally less than 20kms.
Liquid hydrocarbons that are sometimes produced together with natural gas or the liquid formed when a vapour cools (condensation).
Temperature at which a vapour, contained in a closed vessel at a given pressure, will first form liquid on the subtraction of heat.
A solid compound formed by the chemical union of water with a molecule of some other substance. Hydrocarbons with one or four carbon atoms can form hydrates under the right conditions if free water is present.
Liquefied Natural Gas, mostly methane, held in liquid state by the application of low temperature, to facilitate storage.
Liquefied Petroleum Gas, mostly propane/butane held in liquid state by the application of pressure and/or low temperature.
Natural Gas Liquids, condensate derived from natural gas.
Those liquid hydrocarbon mixtures containing essentially pentanes and the heavier hydrocarbons, which have been extracted from natural gas.
Gas that has sour components, e.g. H2S or other corrosive sulphur compounds.
Hydrocarbon gases essentially free from sulphur compounds.
Gas which contains a significant amount of CO2.
Two Phase Flow
Simultaneous flow of gas and liquid in the same pipeline.
Simultaneous flow of two or more fluid phases (i.e. gas, oil and water) in the same pipeline.
Solid or semisolids (i.e. gel) tool which is driven through the pipeline by differential pressure developed across it. This is used for cleaning, gauging, inspection and batch separation.
Pressure vessel designed to allow pigs to be launched (pig launcher) and received (pig receiver) using pipeline fluids as the driving medium.
Externally located indicator which detects passage of pigs.
An hydraulically inflated rubber/polyurethane sphere used as a pig to separate fluids in a pipeline, or to remove condensate, filled with inhibited water to a 102-105% of diameter.
Pig fitted with scraper blades to remove wax coating.
Substance added to pipeline fluids to inhibit corrosion or hydrates.
Vessel designed to collect periodic slugs of liquid from a twophase pipeline.
The practice of augmenting the normal supply of gas during peak or emergency periods from another source where gas may have
either been stored during periods of low demands, or manufactured specifically to meet the demand. Line Pack
A method of peak shaving by withdrawing gas from a section of the pipeline system in excess of the input into that section, i.e., normally, the difference between the actual volume of gas in the pipeline at low flow (increased pressure) & that at normal flow.
Time period to which the pipeline is designed to operate from initial installation or use until decommissioning of the pipeline.
Ratio of the hoop stress in the pipe at the design pressure to the yield stress of the pipe material.
Maximum Allowable Operating Pressure is the maximum pressure under routine operating conditions or maximum value of all pressures including random transient pressure surges caused by unexpected incidents.
Maximum allowable ratio between the stress produced by the maximum service pressure of the circulating fluid and the elastic limit of the steel.
Flow with Reynolds number less than 2000. In this flow, the flow patterns of fluid patterns are laminar and parallel, since any tendency towards turbulence is counteracted by forces of viscosity.
Flow with Reynolds number in a range going from between 1000 to 4000, to a high limit depending on the roughness of the pipe wall.
Gauge pressure + atmospheric pressure.
Pressure of the weight of air and water vapour on the surface of the Earth. Approximately 14.7lbf/in 2 at sea level.
Pressure generally shown by measuring devices. It is the pressure in excess of that exerted by the atmosphere.
Supervisory Control and Data Acquisition. A system that controls the gathering and polling of data relating to the pipeline(s), processes the data, controls the running of any pipeline model, and activates alarms and other monitoring routines.
America National Standard Institute
America Society of Mechanical Engineering
Institute of Petroleum
Institute of Gas Engineers
America Petroleum Institute
Det Norske Veritas
America Society of Testing and Material
National Association of Corrosion Engineers
CODES AND STANDARDS Some of the applicable Codes and Standards used in the design, construction and testing of pipelines include: ANSI/ASME B31.8 Gas transmission and distribution piping system ANSI/ASME B31.4 Pipeline transportation systems for liquid hydrocarbons and other liquids API 5L
Specification for line pipe
Recommended practice for railroad transportation of line pipe.
Recommended practice for transportation of line pipe on barges and marine vessels
Recommended practice for liquid petroleum pipelines crossing railroads and highways
Standard for welding pipelines and related facilities
API RP 1110
API Recommended practice for pressure testing of liquid petroleum pipelines
API RP 1111
Recommended practice for design, construction, operation and maintenance of offshore hydrocarbon pipelines.
Steel valves (Flanged and Butt-welding End)
Ring-Joint gaskets and grooves for steel pipe flanges
Steel pipe flanges and flanged fittings
Welded and seamless wrought steel pipe
BS 8010 Part 1&2
Pipelines on land: Design, construction and installation.
BS 8010 Part 3
Subsea Pipelines: Design, construction and installation.
DNV Rules for submarine pipeline systems DNV RP E305
On-bottom stability design of submarine pipelines
IP (Part 6)
Model code of safe practice - Petroleum pipelines
Control of external corrosion on underground or submerged metallic piping systems
Control of corrosion on offshore steel pipelines
PIPELINE ENGINEERING DELIVERABLES Pipeline design covers the full design life of the pipeline, and consequently, maintenance and inspection methods / procedures should be considered during the design process. 3.1
A number of work procedures are applicable in the pipeline group. Project specific procedure usually called Pipeline Discipline working procedure is prepared by the responsible discipline engineer in a project and endorsed by the project QA/QC personnel prior to approval by the Project Manager. Basically, the discipline working procedure states the pipeline intended scope of works and highlights the resources (codes/standards, software, discipline team, etc) to be used in executing the project. 3.2
INPUT TO PROPOSALS
For any proposal, the scope of work to be undertaken is determined by the pipeline engineer from relevant documents provided by the Client. Also, since most projects are interdisciplinary by nature, proposal meetings are held where the pipeline engineer interacts with other discipline personnel to further clarify his scope of work and responsibilities. The input to proposals by the pipeline engineer can be broken down as follows: (i)
Preparation of Man-hour Estimate
A list of deliverables expected to be produced during the project execution is prepared based on proposed designs to be undertaken and materials required. Based on the
number of deliverables and the extent of activities expected, the man-hour estimate is prepared. The methodology involved in producing man-hour estimate includes: Step 1 Carefully study the pipeline engineering / discipline scope of activity contained in the tender / proposal document Step 2 List out the expected deliverables (studies, calculations, specifications, drawings, data sheet, material requisitions, etc.) Step 3 Using the Engineering scope and man-hour summary form (F-5054-Pipelines), input the information of step 2 including the associated hours. See Appendix for form F-5054 Engineering scope and man-hour summary (Typical) for the Pipelines group. Step 4 Pipeline LDE to check the deliverables / estimated hours against the standard discipline default man-hour and revise as appropriate. Step 5 Submit the LDE approved man-hour to the Proposal Manager for review/approval and subsequent inclusion in the overall engineering man-hour summary. (ii)
Arising from the project specific requirements, discipline execution plan is prepared. This would be in accordance with the ITB and is to be submitted to the Proposal
Manager for inclusion in the proposal documents. The basic information to be contained in the discipline execution plan includes:
Outline of activities to be executed by the discipline
Methods and tools to be used
Deviation from Client ITB method if any
Any other requirement(s) as may be directed by the Proposal Manager
DESIGN DELIVERABLES For any project involving pipeline design activities, the deliverables list depends on the work-scope established by the Client. However the following list includes the common deliverables produced in a pipeline design effort:
Material Specifications (Line pipe, Bends, Valves, Risers, Pig traps, etc.)
Other Specifications (Welding, Installation, Hydrostatic tests etc.)
Pipeline Mechanical Design -
Wall thickness determination
Stress Analysis (Buckling, expansion, span, crossing, installation etc.)
Material Data sheets (Linepipe, valves, bends/fittings, pig traps, etc.)
Material Take-off (MTO)
Pipeline planimetry (route map)
Pipeline alignment sheet
Crossing drawing (Road, river, pipeline, rail, etc.)
Riser guard / clamp detail
Kilometer marker post drawing
Pig launcher / receiver details, etc.
Design studies In some projects, pipeline design studies are necessary in order to carry out effective, efficient and safe design. The common areas include routing, material selection, pigging, hydraulic study, constructability study, etc. In each study case, experience and sound judgement are pertinent.
Route selection report This deliverable only applies where the client has not firmed up the desired route for the pipeline. The methodology for routing a pipeline involves extensive studies and discussions with landowners and appropriate authorities. The major factors governing the choice/selection of a pipeline route includes economic, technical and safety considerations. The shortest route may not always be the most suitable. In choosing a pipeline route, the following main factors should be considered:
Pipeline operating conditions and requirements
Terrain and subterranean conditions
Hazards and obstructions
Existing and future land/seabed use etc
It is noteworthy to mention here that it is necessary to carry out a survey of the pipeline route and choosing a tentative route should be preceded by a desk study. (c)
Design Basis This is sometimes referred to as design premise, basis of design, design memorandum etc. It contains all the information necessary for the specific design, installation and testing of the pipeline. This includes information on the route, pipeline operating conditions (flow, pressure, temperature etc), fluid characteristics, design and installation requirements etc. As the name implies, it outlines the design requirements of the entire pipeline system and serves as a guide to the engineering design of the pipeline. Therefore, the deliverable is first among others.
Material Specifications These documents outline the technical requirements for the specific pipeline items/equipment in question. The commonly prepared material specifications include those for: -
Line Pipe and Bend Material
Flanges and other Pipeline fittings
Pig launcher and receiver etc.
Pipeline material/equipment specification must state the following as a minimum: -
Process of manufacture of the material/equipment
The tests to be carried out on the item(s)
Quality control/assurance measures
Transportation / Delivery conditions.
For the above information, appropriate codes/standards are used in addition to Client specific requirements and experience. (Refer to Section 2.2 for Codes and Standards). (e)
Construction / Installation Specifications This is similar to the above except that here, the pipeline engineer specifies the types/methods of construction/installation, testing and pre-commissioning / commissioning requirements. Use of codes/standards/Client requirements and experience is also necessary.
Pipeline Hydraulics Hydraulics is the study of flow of fluids under an external force. In pipeline hydraulics, the engineer considers fluid flow conditions, whether the fluid is compressible (gas) or incompressible (liquid). This is with the view to determining the appropriate pipe or line size for the pipeline. This is achieved by determining the pressure loss and any temperature changes along the pipeline
length. The analysis of pressure losses in pipelines is critical as these losses have a significant impact in installation cost, operating cost and also the pipeline capacity i.e. size. Some design software/literature are available for hydraulic analysis. Software includes PIPESIM, PLGAS, and PIPEPHASE etc. Typical ranges of economic velocities are as follows: Liquid Pipelines
1.5 to 2.5 m/s
Single phase liquid
1.0 to 4.5 m/s
Single phase gas
less than 18 m/s to limit noise
Two phase gas/liquid
Greater than 3m/s and less than fluid erosional velocity
(Erosional velocity, Ve = 122*1/ρ1/2, where ρ is fluid density, Kg/m3) (g)
Pipeline Mechanical Design This relates to the overall design for strength and integrity of the pipeline system. The engineer carries out calculations and analysis to determine the appropriate requirements for the pipeline. The calculations/analysis carried out include:
Pipeline wall thickness calculation
In most cases, the pipeline wall thickness calculated is governed by applicable codes/standards (e.g. ANSI B31.4 & B31.8, DNV etc.). The wall thickness determination is based on the design internal pressure or the external hydrostatic pressure (in the case of subsea pipelines). Reference to the pipeline
design codes/standards or specific requirements from the Client should always be made.
Pipeline stability calculation
Stability analysis of pipelines is usually carried out where the pipeline is planned to be installed in a swamp (high water table area) or offshore area (on the seabed or buried). In each case, the hydrodynamic loads on the pipeline are analyzed and the required submerged weight for stability of pipeline is determined. Depending on the required submerged weight, concrete coating of the pipe may be necessary.
Stresses are imposed on the pipeline by internal and external factors. These include stresses due to fluid operating conditions (pressure and temperature), environmental and installation conditions. The stresses are analyzed under various criteria e.g. buckling (lateral or upheaval), pipeline expansion, span analysis, installation stress analysis, crossing (due to specific crossing requirements) etc. In each case, the imposed stress is obtained and checked against the code or Client allowable stress value. However, in span analysis, the intent is to determine the allowable pipeline span length based on the avoidance of excess stress levels (which may lead to pipeline vibrations or oscillations). Design software like AUTOPIPE etc. can be useful. (h)
Pipeline Material Take-off (MTO) This summarizes the pipeline material requirements obtained through the engineering design. It presents quantities of materials, type, grade, class of
material etc. In preparing this, a percentage (1% - 10%) margin or allowance is usually given to allow for possible wastage or contingency. (i)
Material Data sheets Data sheets are used to summarize the technical requirements / information about the respective pipeline materials. Design/operating parameters, testing conditions, material type, quantity, tag no. (if applicable), material requisition number (if applicable) etc. are information given in the data sheet.
Drawings Various pipeline construction drawings are produced based on the specific project requirement. The most common drawing is the Pipeline Alignment sheet. As the name suggests, the drawing summarizes all the relevant data needed to define the pipeline route and the detail design of the pipeline from one point to another. The sheet(s) covers consecutive sections of the pipeline and are usually divided into strips containing the following information: Plan of survey details, ground profile and construction details. Other pipelines drawings include crossing drawings (river, rail, road, pipeline crossing etc.), kilometer marker post, bathymetry drawings, riser detail drawings, pig launcher/receiver drawings etc.
INTERFACE WITH OTHERS
OTHER ENGINEERING DISCIPLINES In NETCO, there are other disciplines that feature in pipeline projects. These may include Corrosion, Control systems / Instrumentation, Mechanical, Civil /
Structural, Piping, Process and Electrical. Direct interface or coordination with any of the discipline engineers depends on the project scope and requirements. For instance, the corrosion engineer’s input is required in determining the corrosion rate of the internal/external environment of the pipeline. Also he advises on the right corrosion control/mitigation methods to be adopted. Similarly, the process discipline engineer would advise on the fluid operating conditions and sometimes provide initial design conditions. In the final analysis, there should normally be review of project deliverables by other relevant disciplines prior to issue of such documents to the Client. This ensures uniformity of information from the project team. 4.2
PROJECT CONTROLS Interface with project controls on a project is always present. As the project controls section is always involved in project planning, monitoring, cost control and cost estimation, the pipeline engineer makes necessary input to the project controls specialist on the project. The pipeline engineer’s man-hour estimation vis-à-vis deliverable preparation status is checked and reported on by the project control specialist as part of project management effort. The pipeline engineer’s responsibility under here include:
Preparation of weekly discipline project report highlighting deliverables started, completed or reviewed/issued for internal checks/client review or approval.
Completion of weekly/Biweekly man-hour timesheets.
Participation in the weekly progress meeting, etc.
PROCUREMENT Procurement activities on a project (where applicable) involve the acquisition/purchase of pipeline equipment/materials and services for the project. Included in this acquisition is the checking/review of vendor or manufacturer’s data. The pipeline engineer’s responsibilities include: Preparation of material take-off (MTO) Preparation of material requisitions (MRs) Participation in the preparation of bidders’ list Evaluation of technical bids/proposals Review/approval of vendor or manufacturer’s drawings and data. Vendor Liaison meetings Inspection at Vendor / Manufacturer’s shop (if applicable).
UNIT CONVERSION FACTORS Length 1in.
Liquid Volume 1 oz 1 gal (US)
= 0.134 ft3
1 gal (Imp) 1 barrel
= 42 gal (US)=
158.99litres = 5.6146 ft3
Mass 1 lbm
= 0.4536 kg
= 1 lbf sec2/ft
=32.174 lbm = 14.59 kg
lbm = pound of mass; lbf = pound of force
Weight = force when gravity is 32.17 ft/sec2 or 9.81 m/sec2.
= 4.448 N
= 32.174 poundals
= 1 kg*m/sec2
1 ton (short)
= 907.2 kg
1 ton (long)
= 1016.0 kg
= 224.8 lbf
Density 1 lbf/in3
= 27.68 g/cm3
1 lbf/ft3 (pcf)
Pressure or Stress 1 psi
= 0.006895 Mpa = 6.895 kPa = 6895Pa
= 68947 dynes/cm2
= 0.0703 kg/cm2
= 0.0680 atm
= 0.0685 bar
= 47.88 Pa
= 4.882 kg/m2
Flow 1 gal/min
= 0.472 l/s
= 0.159 m3/hr
= 158.99 m3/day
Viscosities Kinematic (ν) 1 ft2/sec
= 929 cm2/s (stokes)
= 92903 cs (centistokes)
Absolute (μ) 1 lbm/sec*ft
= 14.88 Poise (g/s*cm)
= 1488 cp (centipoise)
= 47880 cp
= 0.001 Pa*s
Note: ν = μ/ρ
Energy 1 cal
= 4.184 J
= 778.2 ft*lbf
= 1.3556 J
= 0.324 cal
1 ft3*lbf/ in2
= 46.66 cal
= 1055 J = 252 cal
= 0.2931 W*hr
= 0.000393 hp*hr
The SI unit for energy is the Joule (J) but calories are commonly used.
The conversion factors for Btu and calories depend on the temperature. The values given above are the main values.
Power 1 Btu/hr
= 0.2931 W
= 0.00039846 hp (metric)
1 hp (Imp.)
= 745.7 W = 1.0139 hp (metric)
1 ft lb/min
= 0.0226 W
1 ft lb/sec
= 0.324 cal/s
The SI unit for power is the Watt (W) = 1J/s; however, horsepower (SI) is often used (735.5W). SI and Imperial systems have different hp units.
Specific Energy (or Latent Heat) 1 Btu/lbm
= 2.326 J/g
= 0.556 cal/g
Specific Energy per Degree (Specific Heat) 1 Btu/lbm*oF
= 4.186 J/g*oC
= 4186 J/Kg*K
= 1.0007 cal/g*oC
= 130.1 J/Kg*K
Note: Degrees Celsius and Kelvin can be used interchangeably in these formulas.
Heat Flux 1 Btu/hr*ft2
= .0003155 W/cm2
= .00007535 cal/s*cm2
= .2712 cal/hr*cm2
Heat Transfer 1 Btu/hr*ft2 *oF
= .0005678 W/cm2*oC
= .0001356 cal/s*cm2*oC
1 Btu/hr*ft2 *oF
= 4882 cal/hr*m2*oC
Thermal Conductivity 1 Btu/hr*ft *oF
= 0 .0173 W/cm*0C
1 Btu/hr*t *oF
= 1.731 W/m*0C
= 0.004134 cal/s*cm*0C
Speed 1 knot
= 0.514 m/s
1 mi/hr (mph)
= 1.61 km/hr
= 1.688 ft/s
= [(9/5) *0C] + 320F
= (0F - 320F)*(5/9)
= K – 273.15
= Degrees Rankine
= Degrees Kelvin
R F C C F R
R – 459.67