AN INNOVATIVE APPROACH TO HAZARDOUS AREA CLASSIFICATION – THREE DIMENSIONAL (3D) MODELING OF HAZARDOUS AREAS Copyright Material IEEE Paper No. PCIC-(do not insert number) Vaibhav Shrivastava, PE
Ganesh Mohan, PE
Nir Feinstein, CEng UK
Neeraj Bhatia, PE
Member, IEEE Bechtel OG&C 3000 Post Oak Blvd Houston, TX 77056 USA
[email protected]
Member, IEEE Bechtel OG&C 3000 Post Oak Blvd Houston, TX 77056 USA
[email protected]
Member, IEEE Bechtel OG&C 3000 Post Oak Blvd Houston, TX 77056 USA
[email protected]
Senior Member, IEEE Bechtel OG&C 3000 Post Oak Blvd Houston, TX 77056 USA
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Abstract Abstrac t – This paper establishes an innovative approach to represent hazardous areas as true volumes in a plant 3D model and demonstrate increased safety. Examples from an Australian project have been used to compare the classical 2D vs innovative 3D approach. The 2D approach relies on plan and elevation elev ation drawings to show the hazardous areas from various sources of flammable release. Whereas, the 3D approach utilizes data rich 3D models used for the design of petrochemical plants.
flammable liquids and gases within petrochemical facilities create flammable atmospheres that can last for significant periods of time. Catastrophic explosions initiated by electrical equipment within petrochemical and mining facilities over the past century have led to the development of technical standards and explosion protection technology for electrical equipment. Evaluating the chemical composition, likelihood and spatial extension of flammable atmospheres from sources of release within a
Industry standards (IEC, AS/NZS) require identification of all sources of release including piping (vents, flanges, etc.), identification of Electrical Equipment in Hazardous Areas (EEHA), preparation of Hazardous Area Verification Dossier (HAVD) and completion of detailed inspections. Such requirements may get adopted in North America as evidenced with the acceptance of IEC standards in Canada and Gulf of Mexico Offshore facilities [2][3]. The 3D approach automates the generation of EEHA list vs the error-prone manual identification using 2D layouts. The 3D approach allows capturing hazardous areas from piping sources, whereas, the 2D approach generally uses a note referencing a typical detail from a standard. The 2D approach requires man hour intensive physical walk downs and remedy of non-compliances during the construction phase. However, the 3D approach allows performing virtual walk downs of the facility to mitigate non-compliances
petrochemical facility allowsdepicting for the hazardous determination of hazardous areas. Visually areas allows for the design of safer petrochemical facilities by locating electrical equipment outside hazardous areas or selecting electrical equipment that are designed for hazardous application. The applicable technical standards are significantly prescriptive and ample with regards to determining hazardous areas. They provide guidance for the scope and form of deliverables in which hazardous areas are depicted to support the design, construction and maintenance of petrochemical facilities. The current industry practice to classify hazardous areas, denoted as the classical approach in this paper, is to identify the types of sources of release, utilize typical details and guidance from technical standards for shapes and extents of hazardous areas, and delineate the plan and elevation views of hazardous areas
during detailed design thus preventing sc hedule schedule delays,the design rework andphase, replacement of equipment. The 3D approach presented sets an effective methodology for hazardous area classification thereby delivering safer petrochemical installations.
on The 2D drawings. application of the approaches discussed in this paper pertain to the flammable gas and vapor atmospheres. However, this approach can also be extended to the atmospheres containing combustible dusts or ignitable fibers and flyings as well.
Index Terms Terms — Innovative, 3D, 2D, Dossier, EEHA, Zone, Division, IEC, AS/NZS, API, NFPA, 60079, Hazardous, Electrical, Classification, Safety, CEC.
I.
BACKGROUND
Electrification of coal mines in the early 20th century introduced a whole new set of ignition hazards initiated by electrical equipment. For example, a 1913 British mine explosion in Senghenydd Colliery led to over 400 fatalities caused by the ignition of firedamp (methane) build up when
II.
There are two widely recognized systems to classify hazardous areas: NFPA-based Division system and IECbased Zone system. The Division system prevails in North America, Americ a, wherea whereas s the rest of the w world orld gener generally ally uses the Zone system. The technical standards utilized worldwide for the classification of flammable gas and vapor atmospheres are shown in Table I.
an electric spark occurred from the electrical bell signaling gear [1]. Releases, including fugitive emissions, of
OVERVIEW – TECHNICAL STANDARDS FOR HAZARDOUS AREAS
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TABLE I GLOBAL TECHNICAL STANDARDS FOR HAZARDOUS AREA CLASSIFICATION United States* (Division System and Zone System) API RP 500, 500, API API RP 505, NFPA 497
III. PREPARATION OF HAZAROUS AREA DELIVERABLES
Outside United States (Predominantly Zone System)
IEC 60079-10-1, API RP 505, AS/NZS 6007 AS/NZS 60079.10.1 9.10.1 (Australia/New Zealand), EI 15 (UK) formerly known as Institute of Petroleum IP 15 * The United States Coast Guard (USCG) is responsible for the safety and security in the US Offshore Continental Shelf (OCS). USCG allows use of electrical equipment certified under IECEx Certification Scheme in the Gulf of Mexico Offshore facilities. Nationally Recognized Test Lab (NRTL) registered with the IECEx Certification Scheme utilizes the IEC 60079 series of design standards for testing and certifying explosion protected (Ex) electrical equipment. Refer to Section 110.10-1 and 111.105-3 of [2].
The US and Canada recently revised installation codes to recognize the Zone system for Hazardous Area Classification. Canada has introduced the design requirements of IEC 60079 [3] and all new installations in Class I hazardous locations must use the Zone system of classification [4]. Existing Canadian installations may continue to use the Division system or opt to re-classify using the Zone system. In the US, all existing and new installations can either continue to use the Division system or re-classify using the Zone system [5]. Outside the US and Canada, IEC 60079 series of standards are predominantly utilized for the classification of hazardous areas, design, selection, certification, installation, inspection and maintenance of EEHA. Australia and New Zealand utilize AS/NZS 60079 standards which have been reproduced from the IEC 60079 standards. Furthermore, the Local Regulatory Authorities of Queensland State (Australia) require a third party hazardous area compliance audit prior to energizing electrical equipment on a new petrochemical facility. Section 4.2 of IEC 60079-14 [6] mandates the requirements of the verification dossier to be prepared for EEHA. HAVD consists of hazardous area classification documentation, electrical equipment documentation including certification and other design documents for the verification of electrical installations in hazardous areas. Section 4.3 of IEC 60079-14 [6] requires that an initial inspection of “detailed “detailed ” grade (detailed inspection) be carried out on EEHA in accordance with IEC 60079-17 [7] prior to its first use. Detailed inspection is defined as “inspection which encompasses those aspects covered by a close inspection and, in addition, identifies those defects, such as loose terminations, which will only be apparent by opening the enclosure, and/or using, where necessary, tools and test equipment.” equipment.” [7]. To meet these requirements, it is necessary to accurately identify all EEHA and compile the HAVD. Section 9.2 of IEC 60079-10-1 [8] states “ Area classification documents may be in hard copy or electronic form and should include plans and elevations or three dimensional models, as appropriate, which show both the type and extent of zones, equipment group, ignition temperature and/or temperature class.”, class.”, thereby allowing
the use of 3D modeling for the delineation of the hazardous areas.
It is important to understand the work process for the preparation of Hazardous Area deliverables and verification of electrical installations in hazardous areas, viz. from Sources of Release (SoR) schedule to the compilation of HAVD. This allows appreciating the steps for the preparation of the deliverables and their application. Furthermore, this draws distinct trade-offs between the 2D and 3D approaches for Hazardous Area Classification. A1 illustrates a generic overview of this work process that is discussed subsequently. A.
Components Components of SoR S Schedule chedule
The SoR Schedule dictates Hazardous Area Classification of the various sources of release using criteria and details from the applicable technical standards. The SoR Schedule includes but is not limited to the components shown in Table II. TABLE II SOURCE OF RELEASE COMPONENTS SoR Components Hazardous Equipment List
Hazardous Lines List
Hazardous Vents List Hazardous Buildings List
B.
Description Process equipment (pumps, compressors, etc.) handling flammable gases or liquids including associated stream data (composition, pressure, temperature, etc.). Piping streaming flammable gases or liquids. This captures classification from small sources of release including flanges, valves, drains etc. associated with the hazardous piping. Vents (including pressure relief devices) associated with piping and equipment releasing flammable gases. Buildings handling flammable gases or liquids e.g. analyzer houses, battery rooms inside electrical substation buildings, laboratories, etc.
Classical 2D Approach Approach
The classical approach depicts the hazardous area extents on a 2D drawing using the SoR Schedule. Consideration must be given to the drawings scale to accurately represent all hazardous areas and identify EEHA. For large petrochemical facilities such as liquefaction facilities or refineries, it is not practical to show all hazardous areas, especially from small piping sources of release such as vents and individually scattered flanges, valves, etc. Capturing these would require a drawing scale resulting in an impracticable number of drawings. To keep the number of drawings manageable, common practice is to reference typical details from technical standards via a note placed on drawings. An example of such note is “ All continuously vents” shall be classified per Figure 14B of discharging API RP 505:1997.” 505:1997.
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EEHA are identified upon completion of Hazardous Area Classification drawings. It is straightforward to visually identify electrical equipment located within the hazardous areas of large process equipment. However, it is challenging to do likewise for small piping sources such as vents, flanges, etc. For example, per Figure 14B of API RP 505 [9], continuously discharging vents have concentric spheres of Zone 0 (0.5m radius), Zone 1 (1.5m radius) and Zone 2 (3m radius) hazardous areas. If the vent volume is not individually shown on 2D drawings, electrical
hazardous area volumes. The automation takes into account the actual shape of hazardous area volumes (spherical, cylindrical, etc.) in determining the EEHA. A customized software code constructs a tight (rectangular) box around electrical equipment and tests each corner of the tight box with hazardous area volume. If all corner points are determined to be inside the hazardous area volume, electrical equipment is determined to be engulfed and flagged as “Full “Full ” in the output report. If some corner points are determined to be inside hazardous area volume
equipment such as light fixtures rated only for Zone 2 but located within the Zone 0/1 hazardous area of the vent may end up being neglected and pose an ignition hazard. In order to avoid installing electrical equipment with inadequate explosion (Ex) protection rating, rigorous man hour intensive physical walk downs are required during the Construction phase to identify such unsafe noncompliances. The walk down during construction stage of the project could be a time consuming affair which not only require recording of all such non-compliances and remedial effort required to correct the non-compliances but also update of design documents and HAVD database. Small delays during construction stage could cause huge commercial impacts. If there is stringent start-up deadlines associated with a project, such delays could possibly cause delay in commissioning of the plant, consequently affecting commercially not only the project Contractor but also the
and others are not, then such electrical equipment is flagged as “Partial “Partial ” in the output report. Equipment flagged as “Partial ” requires virtual walk downs to verify if the electrical equipment is inside hazardous area volume or not. The generated Clash Report can contain abundant data about the EEHA such as name (or tag), equipment type, plant area, coordinates, etc. The corresponding clashing hazardous area volume name can also be reported. The format of a Typical Clash Report is shown in A-2. The 3D modeling software provides users the ability to generate 2D drawings from the 3D model. The method to generate the 2D drawings could vary between different software. However, latest 3D modeling software are highly customizable and typically have a “filter “filter ” function which allows extraction of various types of objects on 2D drawings. These objects may include interference
Client.
volumes, piping and its components, process equipment, electrical equipment, etc. Tailored drawing scales can be used for various plant locations to produce even the smallest hazardous areas. Delineating hazardous areas in the 3D environment not only adds accuracy of EEHA identification but also provides the opportunity to perform virtual walk downs during the design phase for early identification of hazardous area clashes, consequently early resolution and mitigation of hazardous area issues. 3D modeling software has the capability to generate Clash Reports, which report clashing between various objects. This is a really powerful function to generate a list of equipment which clash with the hazardous volumes, thus automating identification of EEHA and avoiding error prone manual identification.
C.
Innovative 3D Approach Approach
The advancement of commercially available 3D modeling software technology for industrial applications has led 3D design of petrochemical facilities to become an industry norm. Data rich plant 3D models bring vast benefits to delivering projects by allowing all engineering disciplines (electrical, mechanical, piping, civil/structural, etc.) to interface and integrate their designs within a virtual environment and allow virtual walk downs that provide design assurance. Physical structures are 3D modeled including but not limited to mechanical equipment, interconnecting piping, electrical and instrument equipment, buildings, and pipe racks. Once the plant 3D model has taken its shape, various types of virtual interference volumes are typically created such as egress, maintenance, material handling paths pertaining to the operational safety of the facility. In a similar fashion, it is also possible to create hazardous area volumes around sources of release and realize the benefits of this data rich environment. The hazardous area classification details presented in the SoR Schedule was utilized to create the hazardous area volumes in the 3D model. First the hazardous area volumes associated with the process equipment were created and then virtual walk downs of all hazardous piping was carried out to create the hazardous area volumes around the associated small sources like flanges and vents. Upon completion of the hazardous area volumes in 3D model, software automation is used to generate the Clash Report. This automation process takes hazardous volumes as input and creates an output spreadsheet describing information about the electrical equipment inside
IV. EXAMPLE AUSTRALIAN LIQUIFACTION PROJECT – 3D APPROACH The advantages of the 3D approach are most appreciated when realizing their true potential on projects. The project example selected is for a liquefaction processing facility in Australia comprising of liquefaction trains, power generation, process utilities, storage tanks and export facilities. The findings discussed highly recommend 3D modeling of Hazardous Areas for large petrochemical projects. After the creation creation o off ha hazardous zardous area volume volumes s in the plant 3D model, a virtual walk down was carried out to validate the automated Clash Report results, especially for clashes flagged as “Partial “Partial ”. ”. This was to ensure that electrical equipment is correctly rated and recorded in the HAVD. Significant man hours were spent during the design phase to create the hazardous area volumes, carry out model reviews, and perform virtual walk downs. The observations
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made and design mitigations carried out are recorded in Table III. TABLE III OBSERVATIONS AND MITIGATIONS Observation Several prefabricated pipe rack modules, previously classified as non-hazardous, were identified as hazardous (Zone 2) due to the presence of small hazardous piping sources. The pipe rack modules had numerous electrical equipment including piping instruments, light fixtures, electrical junction boxes, etc. Few mechanical equipment skids, previously identified as located in non-hazardous areas, were found to be located within the Zone 2 hazardous areas volumes of adjacent pipe racks.
A small small number number of lig light ht fix fixtures tures rated for Zone 2 hazardous area were found to be located within Zone 1 hazardous area volumes from hazardous piping vents. Some instrument devices rated for Zone 1 hazardous area were found to be located within Zone 0 hazardous area volumes from hazardous piping vents. A large large num number ber of mechanical mechanical equipment skids were found to have partial clashes with adjacent Zone 0 or Zone 1 hazardous area volumes.
A small small number number of instrument instrument devices not rated for hazardous area, were found to be located within Zone 2 hazardous area volumes from small hazardous piping sources.
Numerous electrical equipment such as light fixtures, sockets, junction boxes, instrument devices, previously identified as located in non-hazardous areas, were found to be located within the Zone 2 hazardous areas volumes.
Mitigation All EEHA EEHA were were found found to be rated for Zone 2 already due to the project standardization, however, design efforts were required to update the HAVD.
All EEHA EEHA were were found found to be rated for Zone 2 already due to the project standardization, however, design efforts were required to update the HAVD and gather additional documentation from suppliers. The light fixtures were relocated in the 3D model and design layouts to move them outside the Zone 1 hazardous area volumes. The instrument devices were relocated in the 3D model and design layouts to move them outside the Zone 1 hazardous area volumes. The 3D model accuracy allowed verifying during the virtual walk down that the actual electrical equipment on the skids were not within the hazardous area volumes. Hence, no design impact. The purchase orders with the suppliers were revised to substitute the nonhazardous rated instrument devices with Zone 2 hazardous area rated instrument devices prior to their shipment. Design efforts were required to update the HAVD. All EEHA EEHA were were found found to be rated for Zone 2 already due to the project standardization, however, design efforts were required to update the HAVD.
Detailed Grade is required for new electrical installations in hazardous areas, i.e. prior to energizing the EEHA. Late identification of EEHA during the Construction phase of a project will cause additional costs to the project with potential schedule impact.
V. BENEFITS OF 3D OVER 2D The Table IV compares the benefits of 3D over 2D approach. TABLE IV TABULATION OF BENEFITS OF 3D OVER 2D 3D Approach Accurate re Accurate represen presentatio tation n of large as well as small hazardous area volumes, e.g. Zone 0 and Zone 1 around hazardous vents (See A-3). Capability to perform virtual walk downs during downs during detailed design phase and proactive design mitigation efforts to avoid locating electrical equipment with inadequate explosion (Ex) protection rating.
Automated Clash Automated Clash Report Reports s can be generated to record EEHA within various zones, 0, 1, and 2. (See A-2) Automated Autom ated generat generation ion of 2D drawings is drawings is possible directly from the 3D model. Renders greater confidence and safety of of the electrical installation in hazardous areas, for e.g. even the partial clashes of electrical equipment with the hazardous area volumes can be accurately captured. (See A-3, A-5 and A-6)
In accordance with Section 4.3 of IEC 60079.14 [6] and Section 4.3.1 of IEC 60079.17 [7], an initial inspection at a
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2D Approach It is possible to show hazardous areas from small piping sources, however for a large facility, the drawing scale required to show all such sources will result in an impracticable number of drawings. To avoid this, a typical detail (See A-4) is conventionally referenced as previously discussed. A design team can use these drawings to manually identify EEHA. All steps involved are manual and prone to human error. Alternate Alter nate solution solution:: Construction representatives perform physical walk downs of hazardous lines to identify EEHA falling within the hazardous areas of small piping sources. Consequently, remedial actions may be required due to EEHA noncompliances found during the walk downs. This will result in additional costs and potential delays, e.g.: Long lead time for equipment replacement, installation rework, review of additional supplier documentation, HAVD revision and detailed inspections. Only manual identification of EEHA can take place.
Hazardous areas are manually delineated on 2D drawings.
Accuracy c Accuracy can an be compromised compromised due to manual verification of EEHA and errors may occur leading to missing EEHA and/or unnecessary classification.
VI. RECOMMENDATIONS FOR IMPLEMENTATION Based on the challenges encountered in the example project using the innovative 3D approach, the following recommendations were noted: 1. Early engagement with mechanical skid suppliers is required to obtain their 3D model compatible with one’s software platform. 2. A decision to implement the 3D approach needs to be aligned with the project procurement strategy and schedule. 3. Equipment tags and descriptions must be correctly completed in the 3D model to avoid erroneous identification in Clash Reports. 4. The availability of expertise to m maintain aintain the 3D model by the Operating Company needs to be discussed early with the EPC Contractor which will define the final deliverable format, 2D versus 3D Model. 5. Engage a 3D database administrator with electrical systems knowledge to set up and support the 3D model work.
[3]
M. Cole, W.G. Lawrence, D. Adams and T. Driscoll, “The Canadian Electrical Code for Hazardous Locations Has No Class – But It Does Have Significant Changes”, Changes”, IEEE PCIC Conference Record, 2015. Part 18, Appendix J, C22.1, 2015 Canadian Electrical Code,, Part I (23rd edition), Safety Standard for Code Electrical Installations. NFPA 70, 2014 National Electrical Code, Code, NFPA. IEC 60079-14:2013, Explosive atmospheres – Part
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[5] [6]
[7]
[8]
[9]
[10]
VII. CONCLUSION 3D modeling of petrochemical plants has become an established practice within the industry, allowing various engineering disciplines to interact, interface and develop the design within a virtual environment. Although the classical 2D approach can be utilized for the identification of EEHA, it is apparent from the project example ex ample discussed in this paper that the innovative 3D approach has the potential to deliver accurate results. Additional design efforts are required to perform the 3D approach however the benefits of the 3D approach presented in the paper recommend that this design effort be undertaken to evade potential rework during the construction phase. The 3D approach renders accurate delineation of hazardous areas, identification of EEHA early in the project and therefore designing a robust electrical installation. The 3D modeling approach to hazardous area classification provides a solution to effectively use plant 3D models to comply with the technical standards requirements to identify EEHA and develop an HAVD. Industry standards are recognizing further the safety assurance benefits to identify rigorously all hazardous sources of release and exposed electrical equipment. The global acceptance of IEC standards is evident by the adoption of IEC 60079 in i n Canada. Innovative 3D approach allows designing and building inherently safer electrical installations for complex petrochemical facilities while also meeting stringent EEHA HAVD requirements of IEC 60079.
VIII. REFERENCES [1]
A. McMillan, Electrical Installations in Hazardous Areas, Elsevier, 1998 Areas, [2] 46 CFR J, Oct 1, 2001, Title 46 of Code of Federal Regulation, Chapter I – Coast Guard, Department of
[11]
Part 14: Electrical installations design, selection and erection (IEC 60079-14, Ed. 4.0(2007) MOD), MOD), Australian/New Austral ian/New Zealan Zealand d Sta Standard™ ndard™.. [12] AS/NZS 60079.17:2009, Part 17: Electrical installations inspection and maintenance (IEC 6007917, Ed.4.0 (2007) MOD), MOD), Australian/New Zealand Standard™.
IX. VITAE Vaibhav Shrivastava is a Senior Electrical Engineer at Bechtel OG&C Houston. He received his MSEE from Missouri University of Science and Technology (formerly the University of Missouri-Rolla) at Rolla where he also worked as a Graduate Teaching Assistant for Electro mechanics laboratory. He joined Bechtel OG&C Houston as a college hire in 2006, and has 10 years of electrical engineering experience working on engineering and design of large oil, gas & chemical projects. He is a licensed Professional Engineer in the state of Texas and a member of IEEE IAS. Ganesh Mohan has over 10 years of business, people, technical safety & risk management experience including but not limited to offshore & onshore industries. He is currently an Engineering Group Supervisor of Process Safety Engineering department at Bechtel OG&C, Houston. He received his MS in Mechanical Engineering from the Texas A&M University, College Station and Bachelor of Technology in Mechanical Engineering from the Indian Institute of Technology Madras, India. He has several peer reviewed publications in his area of expertise. He is a licensed Professional Engineer in the state of Texas and a member of IEEE.
Transportation,, Subchapter J, Electrical Engineering. Transportation
14: Electrical installations design, selection and erection,, IEC. erection IEC 60079-17:2013, Explosive atmospheres – Part 17: Electrical installations inspection and maintenance,, IEC. maintenance IEC 60079-10-1:2015, Explosive atmospheres – Part 10-1: Classification of areas – Explosive gas atmospheres,, IEC. atmospheres API RP 505:1997, API Recomm Recommended ended Practi Practice ce for Classification of Locations for Electrical Installations at Petroleum Facilities Classified as Class I, Zone O, Zone 1, and Zone 2 , API. AS/NZS 60079.10.1:2009, Explosive atmospheres – Part 10.1: Classification of areas – Explosive gas atmospheres (IEC 60079-10-1, Ed.1.0 (2008) MOD), MOD) , Australian/Ne Austral ian/New w Zea Zealand land S Standar tandard™. d™. AS/NZS 60079.14:2009, Explosive atmospheres –
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Nir Feinstein graduated from Imperial College London in 2006 with an Electrical and Electronic MEng degree. Since joining Bechtel Bechtel in 2006 he has gaine gained d design enginee engineering ring and construction experience by working across numerous countries (UK, India, Canada, Australia, USA) on petrochemical projects and is presently an Engineering Supervisor for Electrical and Telecommunications Engineering. He is a registered Charted Engineer (CEng) in the United Kingdom and a member of IEEE. Neeraj Bhatia has a Master of Technology (Management & Systems), Indian Institute of Technology, Delhi, India & Bachelor of Electrical Engineering (Electrical), and is a licensed Professional Engineer (PE) in the State of Texas,
USA and is an IEEE Senior Member and serves as IEEE USA Co-Chair in multiple committees. He is also an active member of the Technical code committees of IEEE (Power & Energy, Transformers & Nano Technology). Neeraj is presently Chief Electrical & Telecom Engineer of the Oil Gas & Chemical GBU of Bechtel Corporation in Houston, Texas, USA, and has worked over 25 years in the field of a variety of Oil, Gas, Chemical & Power Facilities, Power plants and Industrial Plants. He has worked in engineering management, engineering, supervision, field construction and commissioning of electrical power distribution, control and automation systems.
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generation,
APPENDIX A A-1 PROCESS MAPPING OF CLASSICAL 2D & INNOVATIVE 3D APPROACHES
A-2 EXAMPLE OF TYPICAL CLASH REPORT FORMAT
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A-3 SNAP-SHOT FROM 3D MODEL SHOWING VENT HAZARDOUS AREA VOLUMES & ENCROACHMENT ON AN ADJACENT LIGHT FIXTURE
A-4 PROCESS VENT PER FIGURE 14A AND 14B OF API RP 505 [9]
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A-5 SNAP-SHOT FROM EXAMPLE PROJECT 2D DRAWING USING 2D APPROACH
A-6 SNAP-SHOT FROM EXAMPLE PROJECT 3D MODEL USING 3D APPROACH
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