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Table Of Contents
1.
GENERAL ............................................................................................................................................................. 4
1.1
1.2
1.3
1.4
INTRODUCTION ................................................................................................................................................................ 4
PURPOSE ........................................................................................................................................................................ 4
DEFINITIONS.................................................................................................................................................................... 4
EXCLUSIONS .................................................................................................................................................................... 9
2.
CODES AND STANDARDS ...................................................................................................................................... 9
3.
REFERENCE DOCUMENTS ....................................................................................................................................12
4.
DOCUMENT PRECEDENCE ...................................................................................................................................13
5.
SPECIFICATION DEVIATION/CONCESSION CONTROL ...........................................................................................13
6.
QUALITY ASSURANCE/QUALITY CONTROL ..........................................................................................................14
6.1
6.2
6.3
QA/QC PROGRAM ........................................................................................................................................................ 14
COMPLIANCE WITH SPECIFICATION GUIDELINES .................................................................................................................... 14
CRITICALITY RATINGS....................................................................................................................................................... 14
7.
DOCUMENTATION...............................................................................................................................................14
8.
SUBCONTRACTORS/SUBVENDORS ......................................................................................................................15
9.
HANDLING ..........................................................................................................................................................15
10.
DESIGN ................................................................................................................................................................15
10.1
10.2
10.3
10.4
10.5
10.6
10.7
10.8
10.9
10.10
10.11
10.12
10.13
10.14
10.15
10.16
10.17
10.18
THREADED PIPING .......................................................................................................................................................... 15
SOCKET WELD PIPING ..................................................................................................................................................... 15
COMPRESSOR/RELIEF VALVE PIPING ................................................................................................................................... 16
PUMP SUCTION/DISCHARGE PIPING .................................................................................................................................. 16
POTABLE WATER ............................................................................................................................................................ 16
STEAM SERVICES ............................................................................................................................................................ 16
GLYCOL SERVICES ........................................................................................................................................................... 17
CAUSTIC SODA SERVICE ................................................................................................................................................... 17
SULFURIC ACID SERVICE................................................................................................................................................... 17
WET H2S/SOUR SERVICES ............................................................................................................................................... 17
CHLORINE SERVICES ........................................................................................................................................................ 18
LOW TEMPERATURE/REFRIGERATION SERVICES .................................................................................................................... 18
BRINE SERVICES ............................................................................................................................................................. 18
WASTE AND OPEN DRAIN PIPING ...................................................................................................................................... 18
AUXILIARY PIPING SYSTEMS .............................................................................................................................................. 18
FIRE WATER PIPING ........................................................................................................................................................ 18
PIPING SUBJECT TO VACUUM ............................................................................................................................................ 18
AMINE PIPING ............................................................................................................................................................... 19
11.
MATERIALS ..........................................................................................................................................................19
11.1
11.2
11.3
11.4
11.5
GENERAL ...................................................................................................................................................................... 19
PIPE............................................................................................................................................................................. 19
VALVES......................................................................................................................................................................... 21
FLANGES AND CONNECTORS ............................................................................................................................................. 28
GASKETS....................................................................................................................................................................... 30
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11.6
11.7
11.8
11.9
11.10
11.11
11.12
11.13
BOLTING ....................................................................................................................................................................... 30
FITTINGS ...................................................................................................................................................................... 31
PIPE BENDS ................................................................................................................................................................... 31
MITER BENDS ................................................................................................................................................................ 31
STEAM TRAPS ................................................................................................................................................................ 31
UNDERGROUND PROTECTION ........................................................................................................................................... 31
INSULATION................................................................................................................................................................... 31
BRANCH CONNECTIONS ................................................................................................................................................... 32
12.
FABRICATION .......................................................................................................................................................33
12.1
12.2
12.3
12.4
12.5
FABRICATION/INSTALLATION ............................................................................................................................................ 33
MATERIAL TRACEABILITY.................................................................................................................................................. 33
SEAL WELDING .............................................................................................................................................................. 33
POSTWELD HEAT TREATMENT .......................................................................................................................................... 33
COATING AND LINING REQUIREMENT ................................................................................................................................. 34
13.
NON METALLIC PIPING ........................................................................................................................................35
13.1
13.2
13.3
13.4
13.5
FIBER REINFORCED PLASTIC (FRP) PIPING........................................................................................................................... 35
SPOOLABLE FIBRE-REINFORCED COMPOSITE PIPES................................................................................................................ 35
HDPE PIPING................................................................................................................................................................ 35
UPVC PIPING................................................................................................................................................................ 36
CPVC PIPING ................................................................................................................................................................ 36
14.
FIELD PRESSURE TESTING ....................................................................................................................................36
15.
APPENDICES ........................................................................................................................................................36
APPENDIX I – PIPING CLASSES SUMMARY ........................................................................................................................................ 36
APPENDIX II – PIPING CLASSES & BRANCH CONNECTION DETAILS ........................................................................................................ 36
APPENDIX III – CONSOLIDATED PIPE CLASSES CROSS REFERENCE INDEX ................................................................................................ 36
APPENDIX IV – AREA WISE PIPE CLASSES CROSS REFERENCE INDEX ...................................................................................................... 36
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1.
GENERAL
1.1
Introduction
This specification describes the minimum requirements for materials of construction used in the
design, fabrication and installation of process and utility piping systems as detailed below for the
ABU DHABI GAS INDUSTRIES LTD. (GASCO) facilities.
1.2
Purpose
The purpose of this specification is to provide PIPING CLASSES (refer to Appendix II) to
standardize materials and piping components, in order to maximize variety control, improve
reliability, and attain consistency in piping design and maintenance.
Proper use of the PIPING CLASS system can only be made when the underlying principles and
design rules are fully understood, as outlined in this specification. This is particularly important when
circumstances dictate deviation from the standard PIPING CLASSES.
For reasons of
standardization, however, deviation from the PIPING CLASSES should be avoided.
1.3
Definitions
Where used in this specification, the following terms shall have the meanings indicated
below unless otherwise clearly indicated by context of their use.
COMPANY: ABU DHABI GAS INDUSTRIES LTD. (GASCO)
CONCESSION REQUEST: A deviation requested by the CONTRACTOR’S or VENDOR, usually
after receiving the contract package or purchase order. Often, it refers to an authorization to use,
repair, recondition, reclaim, or release materials, components or equipment already in progress or
completely manufactured but which does not meet or comply with COMPANY requirements. A
CONCESSION REQUEST is subject to COMPANY approval.
CONTRACTOR: The party(s) which carries out all or part of the design, engineering, procurement,
construction, commissioning or management of the PROJECT
MANUFACTURER/VENDOR/ SUPPLIER: The party(s) which manufactures and/or supplies the
material/equipment, and provides technical documents/drawings and services to perform the duties
specified by COMPANY/CONTRACTOR’S.
SUBCONTRACTOR/SUBVENDOR: The party(s) which carries out all or part of the design,
procurement,
installation
and
testing
of
the
System(s)
as
specified
by the
CONTRACTOR’S/VENDOR
DRAWINGS: Drawings provided by the CONTRACTOR/VENDOR.
PROJECT: (To be defined)
SHALL and SHOULD: The word ‘Shall’ is to be understood as a mandatory and the word ‘Should’ as
strongly recommended to comply with the requirements of this document
Base Code: Piping in this specification is categorized as the base piping code, unless indicated
either in the individual PIPING CLASS or in the Piping Line List as one of the following categories:
FEED Consultant shall identify the ‘Fluid Service Category’ applicable for each service under the
Project pertaining to piping class and address in ‘Piping Material Specification’ as a FEED
deliverables. EPC Contractor shall verify this fluid service category and develop ‘Piping Class
Summary Table’. Based on this weld acceptance criteria shall be followed.
a.
Category D, a fluid service in which all the following apply: (1) the fluid handled is nonflammable and non-toxic and not damaging to human tissues as defined in ASME B31.3 Para.
300.2; (2) the design gauge pressure does not exceed 10.34 barg; and (3) the design
temperature is between –29oC and 186oC.
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b.
Category M, a fluid service in which the potential for personnel exposure is judged to be
significant and in which a single exposure to a very small quantity of a toxic fluid, caused by
leakage, can produce serious irreversible harm to persons on breathing or bodily contact, even
when prompt restorative measures are taken.
c.
Elevated Temperature Fluid Service, a fluid service in which the piping metal temperature is
sustained equal to or greater than Tcr as defined in ASME B31.3 Table 302.3.5, General Note
(b).
d.
High Pressure Fluid Service, a fluid services use Chapter IX of ASME B31.3 for piping design
and construction.
e.
Severe cyclic conditions: conditions applying to specific piping components or joints in which
computed stress range, SE, in accordance with para. 319.4.4, exceeds 0.8 times allowable
stress value, SA (as defined in para. 302.3.5), and the equivalent number of cycles (N in para.
302.3.5) exceeds 7000; or other conditions that the designer determines will produce an
equivalent effect as per ASME B31.3.
f.
Normal Fluid Service: a fluid service pertaining to most piping covered by this DGS, i.e., not
subject to the rules for Category D, Category M, Elevated Temperature, High Pressure, or
Severe cyclic conditions.
Corrosion Allowance: The additional wall thickness added to the calculated minimum wall thickness
(required to contain the pressure), to compensate for wall thinning due to corrosion.
Design Conditions: Unless otherwise specified, pressures and temperatures listed in Appendix I
refer to design conditions.
Items Descriptions: The item descriptions shown in the individual PIPING CLASSES are abbreviated
and shall not be used for purchase unless accompanied with additional specifications.
Piping: An assembly of piping components used to convey, distribute, mix, separate, discharge,
meter, control, or snub fluid flows. Piping also includes pipe-supporting elements, but does not
include support structures, such as building frames, bents, foundations or any equipment
Piping system: Interconnected piping subject to the same set or sets of design conditions.
Piping Class: An assembly of piping components, suitable for a defined service and design limits, in
a piping system.
Pipe Wall Thickness: Unless otherwise specified, piping component wall thickness, specified in the
individual PIPING CLASSES are based only on design considerations of pressure, temperature, and
allowances for corrosion, erosion, MANUFACTURER's tolerance and any allowance for the depth of
threads or grooves. The piping component wall thickness does not include additional thickness that
may be required to compensate for design considerations such as thermal loads due to restraints,
live loads, hydraulic shock, or loads and sources from other causes, all of which must be considered
in the design of piping systems.
Pressure - Temperature Ratings:
A.
Pressure-temperature ratings for 24 inches and smaller carbon steel, ferritic alloy steel, and
austenitic stainless steel flanges, and valves are based on of ASME B16.5. For flanges 26
inches and larger, ASME B16.47, Series A / MSS SP 44 shall be used for design and PressureTemperature Ratings.
B.
The minimum pipe wall thicknesses are based on the pressure-temperature ratings indicated in
individual pipe class.
These two possibilities are defined in piping classes.
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Allowable internal pressures for pipe have been verified in accordance with ASME B31.3 paragraph
304.1.2 equation (3a), in order to meet the design limits of PIPING CLASSES. In some cases, these
allowable internal pressures are decisive for the design limits of a PIPING CLASS.
Purchase Descriptions: Refer to Piping Classes under Appendix II.
Abbreviations:
ACC
ACCORDING TO
API
AMERICAN PETROLEUM INSTITUTE
ASME
AMERICAN SOCIETY OF MECHANICAL ENGINEERS
ASTM
AMERICAN SOCIETY FOR TESTING AND MATERIALS
AG
ABOVE GROUND
BB
BOLTED BONNET
BBE
BEVELED BOTH ENDS
BC
BOLTED COVER
BE
BEVELED END
BW
BUTT WELDING
CL
CLASS
CALC
CALCULATE
CLA
CLAMP CONNECTOR
CONC
CONCENTRIC
CPVC
CHLORINATED POLYVINYL CHLORIDE
Cr
CHROMIUM
CS
CARBON STEEL
DEG
DEGREE
ECC
ECCENTRIC
EXT
EXTENDED
FB
FULL BORE
FBE
FUSION BONDED EPOXY
FFG
FEMALE RING JOINT GROOVE
FF
FLAT FACE
FEED
FRONT END ENGINEERING DESIGN
FLEX
FLEXIBLE
FLG
FLANGED
FRP
FIBRE REINFORCED PLASTIC
FS
FIRE SAFE
GALV
GALVANIZED
GEAR
GEAR OPERATOR
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GRAPH
GRAPHITE
GRE
GLASS REINFORCED EPOXY
GRP
GLASS REINFORCED Plastic
GRUP
GLASS REINFORCED UNSATURATED POLYESTER
GRVE
GLASS REINFORCED VINYLESTER
HEX
HEXAGONAL
HFW
HIGH FREQUENCY WELDED
HDPE
HIGH-DENSITY POLYETHYLENE
HIC
HYDROGEN INDUCED CRACKING
HORIZ
HORIZONTAL
IN
INCHES
INC
INCONEL / INCOLOY
INST
INSTALLATION
IR
INNER RING
ISO
INTERNATIONAL ORGANIZATION FOR STANDARDISATION
ITCS
IMPACT TESTED CARBON STEEL
L
LENGTH
LR
LONG RADIUS (R = 1.5 D)
LONGIT
LONGITUDINAL
MANUF
MANUFACTURER
MDMT
MINIMUM DESIGN METAL TEMPERATURE
METAL
METALLIC
MECH
MECHANICAL
MM
MILLIMETER
Mo
MOLYBDENUM
NACE
NATIONAL ASSOCIATION OF CORROSION ENGINEERS
ND
NOMINAL DIAMETER
NDE
NON DESTRUCTIVE EXAMINATION
NPS
NOMINAL PIPE SIZE
OS & Y
OUTSIDE STEM AND YOKE
OXYG
OXYGEN
OR
OUTER RING
PBE
PLAIN BOTH END
PE
PLAIN END
PRES
PRESSURE
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PN
NOMINAL PRESSURE
PXT
PLAIN END X THREADED END
PWHT
POST WELD HEAT TREATMENT
Q&T
Quenched and Tempered
RED
REDUCED
RF
RAISED FACE
RTJ
RING TYPE JOINT
S
SERVICE
SBE
SOCKET BOTH ENDS
SCC
STRESS CORROSION CRACKING
SCR
SCREWED ENDS
SE
SOCKETED ENDS
SL
SLEEVED ENDS
SMLS
SEAMLESS
SOHIC
STRESS ORIENTED HYDROGEN INDUCED CRACKING
SOL
SOLID
SPI
SPIRAL
SOUR
SOUR SERVICE
SR
SHORT RADIUS
STC
STANDARD OF CONSTRUCTION
STL
STELLITE
STR
STRAINER
ST
STRESS
STD
STANDARDS
SW
SOCKET WELDING
SWC
STEP WISE CRACKING
SXF
SOCKET END X FLANGED END
SXP
SOCKET END X PLAIN END
SXU
SOCKET END X SCREWED (NPT) END
TBE
THREADED BOTH ENDS
TEMP
TEMPORARY
THD
THREADED
THK
THICKNESS
TR
TRIM
UG
UNDERGROUND
UPVC
UNPLASTICISED POLY VINYL CHLORIDE
VERT
VERTICAL
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1.4
WAF
WAFER
WB
WELDED BONNET
WN
WELDEING NECK
WND
WOUND
Exclusions
Following are excluded from the requirements of this specification:
2.

Pipeline classes designed as per ASME B31.4 and ASME B31.8

Piping related to storm and domestic sewer drainage network.
CODES AND STANDARDS
The following codes and standards, to the extent specified herein, form a part of this specification.
When an edition date is not indicated for a code or standard, the latest edition in force at time of
contract award shall apply.
This specification is based on ASME B31.3 Code for Process Piping and ASME B16.5 Code for Pipe
Flanges & Flanged Fittings.
NOTE:
The limits of piping governed by codes other than ASME B31.3 shall be indicated on the
piping drawings: Piping shall be fabricated in accordance with those Codes (and the
Codes referenced in the individual PIPING CLASSES)
AMERICAN SOCIETY OF MECHANICAL ENGINEERS (ASME)
ASME B 1.1
Unified Inch Screw Threads (UN & UNR Thread Form)
ASME B 1.20.1
Pipe Threads, General Purpose (Inch)
ASME B 16.5
Pipe Flanges and Flanged Fittings: NPS ½ Through NPS 24
ASME B 16.9
Factory – Made Wrought Buttwelding Fittings
ASME B 16.10
Face-to-Face and End-to-End Dimensions of Valves
ASME B 16.11
Forged Fittings, Socket-welding and Threaded.
ASME B 16.20
ASME B 16.21
Metallic Gaskets for Pipe Flanges Ring-Joint, Spiral-Wound and
Jacketed.
Nonmetallic Flat Gaskets for Pipe Flanges
ASME B 16.25
Butt Welding Ends
ASME B 16.34
Valves-Flanged, Threaded and Welding End.
ASME B 16.36
Orifice Flanges
ASME B 16.47
Large Diameter Steel Flanges NPS 26 Through NPS 60
ASME B 16.48
Line Blanks
ASME B 18.2.1
Square, HEX, Heavy Hex, and Askew Head Bolts and Hex, Heavy Hex,
Hex Flange, Lobed Head, and Lag Screws (Inch Series)
ASME B 18.2.2
Nuts for General Applications : Machine Screw Nuts, Hex, Square, Hex
Flange and Coupling Nuts (Inch Series)
ASME B 31.1
Power Piping
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ASME B 31.3
Process Piping
ASME B 31.4
Pipeline Transportation Systems for Liquids and Slurries
ASME B 31.8
Gas Transmission and Distribution Piping Systems
ASME B 36.10M
Welded and Seamless Wrought Steel Pipe.
ASME B 36.19M
Stainless Steel Pipe
ASME B 46.1
Surface Texture (Surface Roughness, Waviness, and Lay)
ASME BOILER AND PRESSURE VESSEL CODE
ASME / BPVC
Section VIII (Div. 1) Rules for Construction of Pressure Vessels.
AMERICAN PETROLEUM INSTITUTE (API)
API Spec 5L
Specification for Line Pipe
API Spec 6A
Specification for Wellhead and Christmas Tree Equipment
API Spec 6D
Specification for Pipeline Valves
API STD 6FA
Specification for Fire Test for Valves
API STD 594
Check Valves: Flanged, Lug, Wafer and Butt-welding
API STD 598
Valve inspection and testing
API STD 599
Metal Plug Valves-Flanged, Threaded and Welding Ends
API STD 600
Steel Gate Valves-Flanged & Butt-welding Ends, Bolted Bonnets
API STD 602
Steel Gate, Globe & Check Valves for sizes NPS 4 ( DN 100) & Smaller
for the Petroleum and Natural Gas Industries
API STD 607
Fire Test for Quarter-turn Valves and Valves Equipped with Nonmetallic
Seats
API STD 608
Metal Ball Valves – Flanged, Threaded and Welding Ends
API STD 609
Butterfly Valves: Double-Flanged, Lug- and Wafer-Type
API RP 5L7
Recommended Practices for Unprimed Internal Fusion Bonded Epoxy
Coating of Line Pipe
API RP 941
Steels for Hydrogen Service at Elevated Temperatures and Pressures in
Petroleum Refineries and Petrochemical Plants
API RP 945
Avoiding Environmental cracking in amine units
AMERICAN SOCIETY FOR TESTING AND MATERIALS (ASTM)
All applicable ASTM standards
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION (ISO)
ISO 1461
Hot Dip Galvanized Coatings on Fabricated Iron and Steel Articles
– Specifications and Test Methods
ISO 5208
Industrial valves - Pressure testing of metallic valves
ISO 9000
Quality management systems – Fundamentals and vocabulary
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ISO 9001
Quality Management Systems – Requirements
ISO 9004
Managing for the sustained success of an organization – A quality
management approach
ISO 10474
Steel and Steel Products - Inspection documents
NATIONAL ASSOCIATION OF CORROSION ENGINEERS (NACE)
NACE MR0175/ISO15156
Petroleum and Natural Gas Industries - Materials for use in H2S
containing Environments in Oil and Gas Production
Part-1 General Principles for Selection of Cracking - Resistant
Materials
Part-2 Cracking - Resistant Carbon and Low Alloy Steels
Part-3 Cracking - Resistant CRA’s (Corrosion - Resistant Alloys)
and other Alloys
NACE TM0177
Laboratory Testing of Metals for Resistance to Sulfide Stress
Cracking Stress Corrosion Cracking in H2S Environment
NACE TM0284
Evaluation of Pipeline and Pressure Vessel Steels for Resistance to
Hydrogen Induced Cracking
NACE RP0391
Materials for the Handling and Storage of Commercial Concentrated
(90 to 100%) Sulphuric Acid at Ambient Temperatures
NACE SP0472
Methods and Controls to Prevent In-Service Environmental Cracking
of Carbon Steel Weldments in Corrosive Petroleum Refining
Environments
BRITISH STANDARDS INSTITUTION (BSI)
BS 1868
Specification for Steel check valves (flanged and butt-welding ends)
for the petroleum, petrochemical and allied industries.
BS 1873
Specification for steel globe and globe stop and check valves
(flanged and butt-welding ends) for the petroleum, petrochemical
and allied industries
BS 6364
Valves for Cryogenic Service
BS EN 593
Industrial valves - Metallic butterfly valves
BS EN 10298
Steel tubes and fittings for on shore and offshore pipelines Internal
lining with cement mortar
BS EN ISO 10497
Testing of Valves - Fire type-testing requirements
BS EN 12266 - Part 1
Industrial Valves - Testing of Metallic Valves - Pressure tests, test
procedures and acceptance criteria - Mandatory requirements
BS EN 12266 - Part 2
Industrial Valves, Testing of Metallic Valves Part 2, Test Procedures
and acceptance criteria – Supplementary Requirements
BS EN ISO 15761
Steel Gate, Globe and Check Valves for sizes DN100 and smaller,
for the Petroleum and Natural gas industries.
BS EN ISO 17292
Metal ball valves for petroleum, petrochemical and allied industries
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MANUFACTURER’S STANDARDISATION SOCIETY – STANDARD PRACTICE (MSS-SP)
3.
MSS SP-25
Standard Marking System for Valves, Fittings, Flanges & Unions
MSS SP-44
Steel Pipeline Flanges
MSS SP-61
Pressure Testing of Valves
MSS SP-75
Specification for High-Test, Wrought, But-Welding Fittings
MSS SP-80
Bronze Gate, Globe, Angle and Check Valves
MSS SP-88
Diaphragm Valves
MSS SP-95
Swage(d) Nipples and Bull Plugs
MSS SP-97
Integrally Reinforced Forged Branch Outlet Fittings- Socket Welding,
Threaded, and Butt welding Ends
REFERENCE DOCUMENTS
The following reference documents, to the extent specified herein shall form a part of this
specification. When an edition date is not indicated for a document, the latest edition in force at the
time of the CONTRACTOR’s proposal submittal shall apply.
Design General Specifications:
DGS 0000-002
Material for Sour Environment
DGS 0000-003
Minimum Shop Inspection and Certification Requirements
DGS 0000-004
Criticality Rating System
DGS 0000-021
P&ID Development
DGS 1300-015
Pipes and Piping Components
DGS 1300-016
Color Code For Piping Material Identification
DGS 1300-030
Process and Utility Field/Shop Pressure Testing
DGS 1300 040
General Piping - Process And Utility Design, Lay-Out And Drawing
DGS 1300-070
Pipe Supports
DGS 1300-080
Steam Tracing
DGS 1300-090
Steam Jacketed Piping
DGS 1300-160
Bolt Torquing /Tensioning Procedure for Flanged Connections
DGS 1300-165
Internal Cleaning of Piping
DGS1300-175
Galvanizing
DGS 1300-185
Fabrication, Handling and Installation of Process and Utility Piping
DGS 1300-190
Traceability of Shop and Field Fabrication Piping Materials
DGS 1300-590
Corrosion Monitoring Philosophy
DGS 1310-010
Plug Valves
DGS 1310-011
Check Valves
DGS 1310-012
Ball Valves
DGS 1310-013
Butterfly Valves
DGS 1310-014
Gate Valves
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4.
DGS 1310-015
Globe Valves
DGS 1470-002
Polyurethane Coating for Bends, Valves and Fittings
DGS 1470-003
Three Layer Polyethylene Coating System
DGS 1470-009
Requirements for Fiber Reinforced Plastic (FRP) Pipes and Fittings
DGS 1482-002
Sanitary/Storm Sewer Systems And Culverts
DGS 1511-034
Instrument Piping Classes
DGS 1674-001
Design, Installation, Commissioning and Monitoring of Cathodic
Protection for Plant Facilities
DGS 1900-003
Fire & Gas Protection Design Basis
DGS 6000-003
Acoustic Insulation for Pipe, Valves and Flanges
DGS 6300-001
Welding and NDE of Piping System
DGS 6300-003
Welding and NDE of Pressure Vessels and Heat Exchangers
DGS 6300-006
Material Selection & Corrosion Control Philosophy
DGS 6500-010
Hot Insulation for Piping & Equipment
DGS 6500-020
Cold Insulation for Piping and Equipment
DGS 6531-020
Materials, Installation and Testing Requirements for Refractory
Systems
DGS 6600-010 Part-A
Painting Specification (Painting for New Metallic Structure)
DGS 6710-001
Preservation and Export Packing
STD 1300-001
Piping Design Standard Drawings
DOCUMENT PRECEDENCE
It shall be the CONTRACTOR’s responsibility to be, or to become, knowledgeable of the
requirements of the referenced Codes and Standards.
The CONTRACTOR shall notify the COMPANY of any apparent conflict between this specification,
national and/or local regulations, the Codes and Standards, and any other specification noted
herein. Resolution and/or interpretation of precedence shall be obtained from the CONTRACTOR in
writing before proceeding with the design/manufacture.
In case of conflict, the order of precedence shall be:
5.

UAE Codes and Regulations

Project Specifications

Design General Specifications

Industrial Codes and Standards
SPECIFICATION DEVIATION/CONCESSION CONTROL
Deviations from this specification are only acceptable where the MANUFACTURER has listed in his
quotation the requirements he cannot, nor does not wish to comply with, and the
COMPANY/CONTRACTOR has accepted in writing the deviations before the order is placed.
In the absence of a list of deviations, it will be assumed that the MANUFACTURER complies fully
with this specification.
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Any technical deviations to the Purchase Order and its attachments including, but not limited to, the
Piping Drawings and Project Specifications shall be sought by the VENDOR only through
Concession Request format. Concession Requests require CONTRACTOR’s and COMPANY’s
review/approval, prior to the proposed technical changes being implemented. Technical changes
implemented prior to COMPANY approval are subject to rejection.
6.
QUALITY ASSURANCE/QUALITY CONTROL
6.1
QA/QC Program
Unless otherwise agreed with CONTRACTOR’S, the VENDOR’S Quality System shall fully satisfy all
the elements of ISO 9001, “Quality Management Systems – Requirements” and ISO 9004,
“Managing for the sustained success of an organization – A quality management approach”.
To ensure that all works are being performed consistently and accurately and to the requirements of
the Project Specifications, the VENDOR shall have in effect at all times, a QA program, which clearly
establishes the authority and responsibilities of those responsible for the quality system. Persons
performing quality functions shall have sufficient and well-defined authority to enforce quality
requirements that they initiate or identify and to recommend and provide solutions for quality
problems and thereafter verify the effectiveness of the corrective action.
Quality Systems and Quality Control requirements shall be identified and included in the
CONTRACTOR’s Purchase documentation. Based on these requirements, the VENDOR shall
develop a QA/QC program which shall be submitted to the CONTRACTOR for review and
concurrence. The VENDOR’s QA/QC program shall extend to SUBCONTRACTOR and / or
SUBSUPPLIER.
COMPANY / CONTRACTOR reserves the right to inspect materials and workmanship standards at
all stages of manufacture and to witness any or all tests. The VENDOR / SUPPLIER, 30 days after
award but prior to the pre-inspection meeting, shall provide the CONTRACTOR with a copy of its
Manufacturing and Inspection Plan for review and inclusion of any mandatory COMPANY /
CONTRACTOR’s witness or hold points.
6.2
Compliance with Specification Guidelines
The VENDOR shall furnish CONTRACTOR with copies of VENDOR’s Inspection and Quality Control
Plan.
Materials and workmanship shall be subject to inspection by CONTRACTOR in the shop and in the
field.
The VENDOR shall supply to the CONTRACTOR, a copy of the relevant “Manufacturing, Inspection
and Test Plan” for review. This document shall be in full accordance with the Vendor Document
Requirement Schedule (or equal), as specified within the purchase order or associated
documentation.
6.3
Criticality Ratings
A Criticality Rating (CR) shall be assigned to each piping section (between pieces of equipment),
and shall be listed on the Material Selection Diagram and the Piping Line list. The calculation
method and checking level requirements (based on Criticality Ratings) are given in DGS 0000-004
‘Criticality Rating System’.
The minimum requirements for factory inspection (based on Criticality Ratings) are given in DGS
0000-003 ‘Minimum Shop Inspection and Certification Requirements’.
7.
DOCUMENTATION
This specification serves as the basis of design for all process and utility piping systems, and thus
shall be used as a reference document for material/component selection during detailed design. No
specific documents, however, will be submitted as a direct result of this specification (other than
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Concession Requests, if applicable). For all materials, Contractor shall submit Vendor and Material
Approval Request along with Technical Comparison Table with deviations, if any with relevant
Manufacturer Specifications / Data sheets / Material Selection Diagram etc as supporting
documents.
8.
SUBCONTRACTORS/SUBVENDORS
The VENDOR (conducting detailed design and/or fabrication of piping) shall assume responsibility
and overall guarantee compliance to this specification.
The VENDOR shall transmit all relevant Purchase Order documents including specifications to its
SUBVENDORS.
It is the VENDOR’S responsibility to enforce all Purchase Order and specification requirements on
its SUBVENDORS.
The VENDOR shall submit all relevant drawings and engineering data from its SUBVENDORS to
the CONTRACTOR.
The
VENDOR
shall obtain
and
submit
all
SUBVENDOR
CONTRACTOR/COMPANY, in addition to the system warranty.
9.
warranties
to
the
HANDLING
Assembly, preservation and preparation for piping bulk shipments shall be in accordance with DGS
1300-185 ‘Fabrication, Handling and Installation of Process and Utility Piping’, DGS 1470-009
‘Requirements for Fiber Reinforced Plastic (FRP) Pipes and Fittings’ and DGS 6710-001
‘Preservation and Export Packing’ as applicable.
10.
DESIGN
10.1
Threaded Piping
Threaded piping is allowed for utility services of Category D fluids. Threaded piping is also allowed
after the primary block valve for instrument and drain/vent connections in process services as
specified in the PIPING CLASSES. For hydrostatic vent/drain without valves or with valves threaded
plug or pipe cap shall be used and shall be seal welded after tests.
Threaded piping shall be assembled with sufficient unions to allow disassembly for maintenance,
however, unions shall be kept to a minimum. Galvanized piping, NPS 3 and above shall be
assembled with flanged joints. Flanges shall be welded to pipes before Galvanizing. Flange mating
surface shall be protected during Galvanizing.
Threaded joints shall not be used in Sour piping services, including VENDOR package piping.
NPT pipe threads in accordance with ASME B1.20.1 shall be used for all threaded joints in piping
systems.
10.2
Socket Weld Piping
Socket welding is the preferred construction method for small process piping, NPS 1½ and smaller
in classes 150#, 300# and 600# NON SOUR SERVICE, except where threaded connections are
required for instrument connections or attachment to a threaded connection on an equipment item or
vent and drain connections.
Socket weld piping shall be assembled with sufficient flanges to allow disassembly for maintenance.
Unions shall be used only for Utility services where included in piping classes. Flanges shall be used
instead of unions where required for steam tracer / steam piping size up to NPS 1½.
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Where a threaded branch outlet from a socket weld piping system is required, generally a socket
weld tee (both straight tee and reducing tee), threaded-one-end nipple, and a cap shall be utilized in
design.
Socket weld joints shall not be used in SOUR piping services including VENDOR package piping.
10.3
Compressor/relief Valve Piping
Full-port valves shall be used in compressor suction headers, compressor surge control piping and
in pressure relief systems
10.4
Pump Suction/Discharge Piping
10.4.1
Permanent Strainers
Permanent strainers in pump suction piping are only required for process reasons. When required,
Y-type strainers shall be installed in vertical suction lines.
When required in horizontal suction lines, Y-type or butt weld tee type or flanged basket-type
strainers can be used. For large suction lines (i.e., NPS 8 and larger).Tee-type strainers shall be
used, unless specified otherwise. The design and material for strainers in chemical services and for
special pump shall fulfill the process and pump requirements, e.g., metering pumps.
Pump suction piping with permanent strainers shall have a fine mesh screen installed upstream of
the permanent strainer.
10.4.2
Temporary Start-Up Strainers
All pump suction piping shall have temporary start-up or commissioning strainers. Pump suction
piping not having permanent strainers, shall have temporary conical suction strainers with 150%
open area. The cone shall be pointing into the flow of the fluid.
10.4.3
Start-Up Bypass
A bypass with a valve as per project pipe class compatible with system design shall be installed
around the pump discharge non-return valve and isolation valve for the following criteria:
10.5

Pump is spared with common suction and discharge lines.

Discharge and suction line design temperatures above 230ºC.

Process fluids that can solidify at ambient temperature (e.g., heavy hydrocarbons).

Cryogenic service or fluid temperature considerably below ambient temperature.
Potable Water
Underground Potable Water piping shall be GRE. Mitre bends are not allowed in GRE piping. The
Gasket material shall be as per GRE Manufacturer recommendations. Aboveground Potable water
piping shall be carbon steel with FBE coated internally. GRE can also be used above ground within
potable water tank farm.
10.5.1
De-mineralized Water Services
FRP piping shall be used for underground system.
For aboveground piping, Stainless Steel material shall be used. For Chlorides in excess of 50 mg/l
containing water, Special Alloy Steels shall be used.
10.6
Steam Services
All carbon steel valves for Steam services shall be flanged (or socket welded based on size and
rating), including those installed in headers, for maintenance purposes. The preferred block valve
for steam service shall be a gate valve with split wedge. For steam services, trim shall be stellited.
Valves used for superheated steam service shall have butt-welded ends.
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For pressure seal or flangeless bonnet gate valves having butt welding ends in class 600 and higher,
the regular end-to-end dimensions shall be equal to the short pattern dimensions as per ASME
B16.10.
10.7
Glycol Services
All Glycol injection valves shall be flanged or socket welded. Valves that require lubrication shall not
be used in this service.
10.8
Caustic Soda Service
When reference is made to the “Caustic Soda Service Chart,” it is intended that the charts shown in
the Corrosion Data Survey, published by NACE shall be used.
Carbon steel welds in Caustic Service shall be stress relieved when required by the “Caustic Soda
Service Chart” and DGS 6300-001 ‘Welding and NDE of Piping System’ or if subject to steam out
without prior water wash.
Piping for Caustic Soda Service shall comply with the following requirements:
10.9

The application of cold-formed parts or cold forming shall be restricted as far as possible.

Hot spots due to direct wall-to-wall contact with steam (or electrical) tracing shall be avoided by
applying spacers (ceramic, glass fiber or filled phenolic resin).

All drawings for the fabrication of carbon steel piping intended for Caustic Soda Service shall be
clearly marked “CAUSTIC SODA SERVICE”.

When PWHT is required, Carbon steel piping shall be clearly identified, either by painting or
fixing an adhesive tape around the parts, to show that it is in CAUSTIC SODA SERVICE with
PWHT.
Sulfuric Acid Service
Concentrated (90% and above) Sulphuric Acid service shall use carbon steel piping in accordance
with NACE RP0391.
Dilute Sulphuric Acid service shall use PVDF / PTFE lined carbon steel piping.
The use of pipe bends and elbows shall be restricted as far as possible. Pipe bends SHALL have a
radius of at least 5 D (where D is the nominal pipe diameter). For the fabrication of sweep-in
connections, standard long-radius elbows (DN 80 (NPS 3) or larger) shall be used.
45° laterals, Y-type or sweep-in junctions shall be used for branches.
Reducers should be avoided. If used reducers SHALL be concentric, except in a horizontal pipe
where a concentric reducer could inhibit drainage (i.e. where the reduced diameter is in the direction
of drainage), in which case an eccentric reducer (bottom flat) should be used. The reduced bore
SHALL match the connecting bore.
In carbon steel systems where turbulence or unacceptably high velocities cannot be avoided, spool
pieces of carbon steel lined with fully-resistant material (PTFE/ PVDF) SHALL be used. The length
of such spool pieces SHALL be at least 20 D.
10.10
Wet H2S/Sour Services
For the purposes of this specification, “Wet H 2S/Sour Service” refers to process streams containing
free water in liquid phase and an H2S concentration which can entail two kinds of metal failure.
Type 1:
SCC (and SOHIC) which occur when the metal is subjected to applied or residual stresses.
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Type 2:
HIC (lamination, blistering, SWC) which occur even the absence of stresses (applied or residual).
Austenitic Stainless Steel 300-series can be used in sour service with chlorides up to 30ppm for
pressure piping, clad piping and/or valve trim. However in case the chlorides are in excess of 30ppm
Austenitic Stainless Steel 300-series should not be used.
All piping components with designated SOUR SERVICE shall meet the requirements of NACE
MR0175 / ISO 15156 Part-1, 2, 3 and DGS 0000-002 ‘Material for Sour Environment’.
10.11
Chlorine Services
Chlorinated dry gas services shall use PVC piping. Water services with chlorine concentrations
greater than or equal to 3500 ppm shall use filament-wound fiberglass reinforced vinyl ester (GRV)
pipe. Fiberglass piping materials and installation shall be in accordance with DGS 1470-009
‘Requirements for Fiber Reinforced Plastic (FRP) Pipes and Fittings’.
10.12
Low Temperature/Refrigeration Services
For the purposes of this specification, “Low Temperature Services” are defined as piping which
operates at, or may be exposed to, temperatures below -15°C. Material shall be impact tested at
MDMT as per ASTM E23 and the acceptance values for sour service in base metal thickness <
100mm, Impact value required: 34 J Min, 41J average; for thickness >100mm, Impact values
required :18J Min , 28 J Average.
Additional requirements to prevent brittle fracture of piping in Low Temperature Service (i.e.,
possible impact testing of materials, limits on material selection and added welding, NDE, and
PWHT requirements) shall be in accordance with DGS 6300-001 ‘Welding and NDE of Piping
System’.
Valves in services with a design temperature below -50°C (-58°F) shall be provided with an
extended bonnet for cryogenic service. Valves with insulation shall also have bonnet extension
based on insulation thickness.
10.13
Brine Services
Glass Reinforced Epoxy pipe (GRE) shall be used for brine services. GRE piping materials and
installation shall be in accordance with DGS 1470-009 ‘Requirements for Fiber Reinforced Plastic
(FRP) Pipes and Fittings’.
10.14
Waste and Open Drain Piping
Waste and Drain system piping for unpolluted Rain Water, Oily Water, and Sanitary Waste Water
shall be in accordance with DGS 1482-002 ‘Sanitary/Storm Sewer Systems and Culverts’.
10.15
Auxiliary Piping Systems
For piping within VENDOR package scope shall meet the requirements of this DGS 1300-010. Any
deviation to this requires COMPANY approval.
10.16
Fire Water Piping
The fire water piping shall be Carbon Steel (FBE coated) for above ground and GRE for
underground.
Fire water piping shall be in accordance with DGS-1900-003 (Fire & Gas Protection Design Basis).
10.17
Piping subject to Vacuum
Piping classes which are designed for vacuum conditions are indicated as FV in relevant piping
class details under pressure-temperature section.
For other pipe classes if subjected to vacuum condition wall thickness calculation shall be carried
out as per ASME Section VIII - Div.1, Section UG-28 and shall be approved by Company.
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10.18
Amine Piping
API RP 945 recommendations shall be applied for amine service piping including closure welds.
For amine service, carbon steel piping and piping component welds including attachments
irrespective of wall thickness, diameter, geometry and kind, the weld shall be post weld heat treated
and no exceptions will be granted by Company in this regard.
11.
MATERIALS
11.1
General
11.1.1
Materials not in Specification
Components not listed in the individual PIPING CLASSES of this specification shall be considered
out-of-specification components and shall, in general, be identified as specialty items with the Tag
Number on the Process & Instrumentation Diagrams (P&IDs) and piping drawings.
11.1.2
Thread Compound
Threaded components shall be joined by using liquid O-ring (Teflon based paste) for temperatures
minus 45°C to 260°C (not to be used in the case of seal welding). “PTFE Tape shall NOT be used.
11.1.3
Forgings
All carbon steel forgings (such as flanges, fittings and valves) shall be normalized. Supplementary
tests are recommended for flanges including impact testing and hydro-testing.
11.1.4
Carbon Steel Piping Components
Carbon content and Carbon Equivalent (CE) of carbon steel base materials for sour services shall
be in accordance with DGS 0000-002 ‘Material for Sour Environment’.
11.1.5
Dual Certified Materials
Material specified as Dual Grade i.e. 316/316L shall be supplied certified to both the grades
specified. All items shall be supplied with mechanical properties to the ASTM product specification
for UNS S31600 (i.e. TP316) and chemical properties to the ASTM product specification for UNS
S31603 (i.e. TP316L). Dual grade materials shall be supplied in the solution treated condition and
shall not be used above 300°C and shall be supplied with hardness test results demonstrating
compliance to NACE MR01-75 / ISO 15156 where applicable. The substitution of single grade
material where dual grade is specified not permitted without prior COMPANY approval. IGC (Inter
Granular Corrosion) tests are required for Austenitic stainless steels and tests shall be conducted as
per ASTM A262.
11.2
Pipe
11.2.1
Wall Thickness
The pipe wall thickness calculations for all metallic PIPING CLASSES are calculated according to
ASME B 31.3. Each PIPING CLASS has the design criteria which are used as the basis for the
calculations.
Piping sizes shall be in accordance with ASME B36.10, however sizes 1 ¼”, 2 ½”, 3 ½”, 5”, 22”, 26”,
28”, 32” and 34” shall not be used unless and until approved by COMPANY.
11.2.2
Pipe Nipple Sizes/Schedules
Pipe Nipples can be used for the same pipe sizes as socket weld and threaded pipe sizes in the
particular Piping Class (usually NPS 1-1/2 and smaller pipe sizes). All Pipe Nipples shall be
seamless. The wall thickness of the Pipe Nipples shall be as listed TABLE 1 below.
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TABLE 1
WALL THICKNESS OF PIPE NIPPLES
CARBON STEEL AND GALVANIZED PIPING CLASSES
Straight pipe Run for Socket weld or
threaded
Pipe Nipple
S/80
S/160
S/160
XXS
XXS
XXS
STAINLESS STEEL, INCONEL, INCOLOY & OTHER ALLOY STEEL PIPING CLASSES
Straight pipe Run for Socket weld
Pipe Nipple
S/40S
S/80S
S/80S
S/160
S/160
XXS
Wherever practicable, metallic pipes shall be specified by reference to the ‘Nominal Pipe Size (NPS)’
and ‘Schedule No. (SCH)’ in accordance with ASME B36.10 and B36.19.
Since stainless steel pipe (ASME B36.19) is limited to only four schedule numbers (5S, 10S, 40S
and 80S), relevant pipes may also be indicated by schedule reference to ASME B36.10, if required.
11.2.3
Design Temperature Ranges
Basic pipe materials and the associated fittings, flanges and valves shall be as follows, whenever
minimum design temperature is the governing factor.
-15 °C through 427°C
Carbon steel
-16 °C through -45°C
Low Temperature Carbon Steel (LTCS)
-46°C and below
Austenitic Stainless Steel
Carbon steel shall be impact tested as per ASME B31.3 Para. 323.2.2 and DGS 6300 006
depending upon the wall thickness and design minimum temperature.
11.2.4
Corrosion/Erosion
Where corrosive or erosive conditions are the governing factor, corrosion/erosion resistant materials
shall be used.
11.2.5
11.2.6
Corrosion Allowance

Minimum corrosion allowance for pipes shall be 1.6 mm for carbon and low alloy steel in noncorrosive services and 0.0 mm for stainless steel, inconel, incoloy, clad lined and all nonmetallic pipe. Corrosion allowance shall be 3.0 mm for galvanized carbon steel and carbon
steel in corrosives services Corrosion allowance is individually listed in the PIPING CLASSES.

Unless otherwise specified the corrosion allowance for carbon steel shall not be greater than
3.0 mm.
Seamless Pipe
Seamless Pipe shall be used in sizes as specified in the Piping Classes. Generally, seamless
carbon steel pipe shall be used for all process lines up through 16 inch. Stainless steel pipes up to
and including NPS 6 shall be seamless.
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Welded Pipe shall not be substituted in place of seamless pipe unless prior approval by COMPANY.
Due to availability, Welded Pipe which is 100% radiographed along the longitudinal seam to give a
joint efficiency of 1.0 (except API 5L), as defined in ASME B31.3, can be substituted for seamless
pipe.
The joint efficiency and mill tolerance used in the wall thickness calculations for seamless pipe is 1.0
and 12.5% respectively.
11.2.7
Welded Pipe
Welded Pipe having a longitudinal weld joint quality factor of at least 0.85 shall be used in sizes as
specified in the Piping Classes. Electric Fusion Welded (EFW), Submerged Arc Welded (SAW), Gas
Metal Arc Welded (GMAW) or a combination of SAW and GMAW are permitted. No Furnace Butt
Welded or Electric Resistance Welded (ERW) pipe is permitted, HFW is permitted.
Welded Pipe shall only be straight seam; spiral seam pipe is not permitted. Pipe can be welded by a
single or a double butt weld.
The joint efficiency used in the wall thickness calculations for welded pipe made from plate is 0.85
(min.), 0.95 or 1. Mill tolerances used in wall thickness calculations of pipe shall be in conformity
with wrought fittings (ASME B16.9: 87.5 %).
11.3
Valves
11.3.1
General Requirements - Valves
Unless specified otherwise, all valves shall comply with the following:
a.
Valve end connections in piping of class 150#, 300# and 600# - NON SOUR SERVICE shall be
socket weld for the sizes given in the appropriate PIPING CLASSES (generally, NPS 1½ and
smaller). In no situation NPS 2 socket weld valves shall be used.
b.
Valve end connections for utility services of Category D fluids shall be threaded for the sizes
(NPS 1½ and smaller) given in the appropriate PIPING CLASSES.
c.
Wafer and wafer lugged valves shall not be used for SOUR and NON SOUR hydrocarbon
service double flanged valves shall be used. Wafer and wafer lugged valves are permitted for
utility services, where Wafer valve shall not be directly joined to another valve without a piping
spool piece in between.
d.
Butt weld end valves shall not be used in ASME Class 900 & below Piping Classes unless it is
specifically indicated in any pipe class.
e.
Valves packing in vacuum systems shall be checked with supplier before order.
f.
Valves used in temperatures below -50°C (-58°F) shall have extended bonnets suitable for
cryogenic service to provide a gas column surrounding the stem. Valves shall be type tested to
BS 6364 where one valve per group, or 5% per group (whichever is the greater) shall be
cryogenically tested, unless otherwise stated by the COMPANY.
The valve groups are as per the following table where any one combination of size and rating
within the group is suitable for the test.
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Valve Rating
Size Range
(NPS)
150# - 300#
600# - 900#
≥1500
½-1½
2-4
6-8
10 - 14
≥ 16
g.
Socket weld ends on valves in alloy steel (1¼ Cr 0.5 Mo) requiring postweld heat treatment
shall be procured with a minimum 100 mm long plain end pipe nipple at each socket weld end
of the valve which is welded in and heat treated by the MANUFACTURER prior to assembly of
the valve.
h.
All valves in SOUR SERVICE shall be flanged, or butt welded, as identified in the respective
Pipe Material Class. For NON-SOUR SERVICES, NPS ½ - 1 ½ shall be socket welded for
classes up to and including 600#. Socket weld joints shall not be used in SOUR piping services
and in vendor package piping.
i.
Block valves at a tank or equipment interface shall be tight shut-off design.
j.
Ball valves with process operating temperature above 200°C shall be metal seated type.
Alternatively Triple offset / eccentric metal seated valves as per API 609 Category B and DGS
1310-013 ‘Butterfly Valves’ shall be used for sizes NPS 16 and above.
k.
Flanged valves shall not be used in place of socket weld or screwed valves in order to permit
insertion of blanks for isolation. Instead, a pipe nipple and flange shall be installed on the end
of the socket weld or threaded valve that requires the flanged connection.
l.
Flanged valves shall not be used in place of socket weld or screwed valves whenever mounted
directly to vessels or other equipment that has been furnished with flanged connections.
m.
Where “Blow-Down” Valves are specified (i.e., shown on P&IDs), they shall in all cases be
specified as angle body or Y-pattern globe valves with Stellite or cobalt alloy overlay trim.
n.
Full-port valves, when required, shall be identified in the individual PIPING CLASSES, and shall
be indicated FP on the P&IDs. The valve bore size shall be in accordance with API 6D / API
608.
o.
For all valves specified as FIRE SAFE, valve MANUFACTURER shall demonstrate that he has
complied with a Fire Test Standard equal to or better than BS EN 12266 (Part-2), API Std 607
or API Spec 6FA as applicable, with leakage rates equal to or better than the API 6D.
p.
When required, TIGHT SHUT-OFF valves shall be marked TSO on the P&IDs and/or as
indicated in DGS 0000-021 ‘P&ID Development’. TIGHT SHUT-OFF valves shall comply with
the seat leakage rates stated within DGS 1310-012 ‘Ball Valves’. TSO valves shall only be used
when extra seat leakage cannot be tolerated. TSO valves shall be tested for body and seat leak
tests at site after receipt.
q.
All valves shall be capable of being locked in the open or closed position.
r.
Battery limit ESD valves as indicated in DGS 0000-021 ‘P&ID Development’ and any other
valve specified as critical by the COMPANY shall be classified as a critical valve. They shall be
seal tightness tested at site before installation. This shall be witnessed by COMPANY.
s.
When specified, stem extension is provided to get lever out of the insulation for low temperature
carbon steel valves for continuous operations below - 50°C (-58°F). Length of extended stem
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shall be calculated in accordance with insulation thickness as stated in DGS 6500-020 ‘Cold
Insulation for Piping and Equipment’.
11.3.2
t.
Refrigeration block valves shall be globe in all cases. Due to the lack of standardization among
refrigeration valve MANUFACTURERs (e.g., varying face to face dimensions) mixing brands
would be detrimental to continuity required in the fabrication and maintenance areas for these
systems. .
u.
All trunnion mounted ball valves shall have the trunnion integral with the ball. The trunnion shall
be protected with trunnion wipers to prevent debris entering the trunnion cavity. All trunnion
mounted ball valves size 8” and above shall include secondary seat sealant injection. All Ball
Valves in Sour/toxic service shall have secondary sealant injection having grease points with
heavy duty double check valves and grease nipples to be fitted with caps as per project pipe
classes for the stem, seats and trunnions.
v.
When trim Inconel 625 is specified in sour service for carbon steel valves, contact between seat
and disc/flaps/ball can be overlayed as per DGS 0000-002 ‘Material for Sour Environment’ and
DGS 6300-003 ‘Welding and NDE of Pressure Vessels and Heat Exchangers’.
w.
For valves in sour/corrosive services, all auxiliary connections drain, vent, sealant injection,
grease points etc. on the valve body shall be butt welded to body and not threaded as threaded
connections are source of corrosion in these services.
x.
Body cavity relief (pressure equalization) provision shall be provided for double seated (i.e.
trunnion mounted ball valves, gate and plug valves) in liquid service subject to fluctuating
temperature where:

Design temperature below -50°C in all ASME pressure classes for all sizes.

In steam and condensate systems for 2” and above.
General Requirements – Valve Trim
The valve trim shall be comprised of as a minimum, of valve components as listed in following table:
Type of valves
Reference Standard
Trim Parts
Ball Valves
API 608 /
BS EN ISO 17292
API 6D
Trunnion (as applicable)
Ball (or Ball and Shank)
Stem
Seat rings housing
Stem seals *
Gate Valves
BS EN ISO 15761 / API
602
API 600
API 6D
Stem
Butterfly Valves
API 609
BS EN 593
Ball / Piston Lift Check
Valves
BS EN ISO 15761 / API
602
Gate seat surfaces
Body seat surfaces or Seat Ring
Back seat contact surfaces (as
applicable)
Seating surface of the body
Seating surface of the disc
Disc, disc to shaft connection hardware
(Keys, Pins, Screws etc.)
Body seat surface
Piston or Ball seat surface
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
Type of valves
Reference Standard
Wafer Check Valves
/ Dual Plate Check Valves
API 594
Swing Type Check Valves
BS 1868
Globe Valves
BS EN ISO 15761 / API
602
BS1873
Needle Valves
BS EN ISO 15761 / API
602
Trim Parts
Body seating surfaces
Plate seating surfaces
Spring *
Pins *
Screws *
Body seating surfaces
Disc seating surfaces
Spring *
Studs, Nuts, Washers and Pins*
Screws *
Stem
Body seat surface
Disc seat surface
Back seat bushing (as applicable)
Disc nut / screws
Stem
Body seat surface
Disc seat surface
Disc nut / screws
Plug Valves
API 599
Stem
Plug
Sleeve
Diaphragm Valves
MSS SP-88
Stem
Diaphragm
Note: Components marked with '*' are in addition to that of referenced standards.
11.3.3
11.3.4
General Requirements - Valve Packing

Graphite based valve stem packing (Graphlock/Garlock Style 98 or equal) shall be used in all
services to control fugitive emissions. Gland packing is mandatory for all valves.

PTFE valve stem packing shall be used in refrigeration services where non hydrocarbons are
used as a refrigerant.
General Requirements - Valve Lubricants
All valve lubricants shall be compatible to the service in which they will be used. Valves in glycol or
LPG services shall not be lubricated, nor shall valves on the inlets of a heat exchanger or any other
piece of equipment where lubricant/sealant would be harmful to the service.
11.3.5
General Requirements - Valve Operators
a.
All manual-operated valves shall normally be hand wheel (or lever) operated. Manual gear
operators, when specified for valve sizes in TABLE 2, shall be fully enclosed type designed to
bolt on to valve yoke and shall be field mountable.
b.
Valves requiring extended bonnet/stem to gain access to the handwheel or gear operator shall
be identified as specialty items on the P&IDs and drawings.
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
c.
The use of chain-operated valves shall be minimized. The application of chain operated valves
requires prior approval from COMPANY (e.g., for safety reasons). The use of chain-operators is
not allowed for valves with extended stems.
d.
Cast Iron Gear Operators are acceptable only if mounted on cast-iron valves.
e.
Gear Operator shall be provided for all valves in 10000# irrespective of size.
f.
Gear Drive Selection:
All valves shall be equipped with Manual Gear Operators as specified in TABLE 2 below:
TABLE 2
MANUAL GEAR OPERATOR REQUIREMENTS FOR VALVES
Valve
Type
Gate
Globe
(Up to
12”)
Rating
150
300
600
900
1500
2500
4500
150
300
600
900
1500
2500
4500
11.3.6
Size
Range
(NPS)
 14”
 12”
Valve
Type
Plug
 8”
 6”
 3”
 8”
 6”
Ball
 4”
 3”
Rating
150
300
600
900
1500
2500
4500
150
300
600
900
1500
2500
4500
Size
Range
(NPS)
 8”
Valve
Type
 6”
High
Perform.
Butterfly
 2”
Lined
Butterfly
 8”
 6”
 4”
 3”
 2”
Lined
Plug
Rating
150
300
600
--150
----150
300
-----------
Size
Range
(NPS)
 8”
 3”
-- 6”
---- 6”
-----------
General Requirements - Valve Installation
a.
Valves should be positioned with their stem pointing upwards; however, horizontally pointing
stems are acceptable. The following exceptions shall be made:

No horizontal positioned stems in Low-Temperature Service shall be accepted. Valves with
an extended bonnet for services below -50°C (-58°F) shall be installed with the stem
vertical or with a maximum inclination of 30° from the vertical: An exception is made for
vent valves, upon COMPANY approval.

Butterfly Valves shall not be installed with the disc shaft in the vertical. The ideal
installation of a butterfly valve should have the disc shaft horizontal and the bottom edge of
the disc opening into the flow.

To avoid accidental blocking owing to a loosened wedge, Gate Valves installed in pressure
relief systems (and flare lines) shall be positioned with the stem pointing horizontally.

Gate Valves in a fouling service should be positioned with the stem horizontal. This is to
mitigate closing problems when bottom cavities are filled with solids/dirt.
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
11.3.7
11.3.8
11.3.9
11.3.10
b.
The preferred orientation for Swing Type Check Valves is horizontal.
c.
Dual plate Check Valves can be installed in the horizontal or in the vertical with the flow going
upward. Dual plate Check Valves shall not be orientated in the vertical with the flow going
downward unless approved by the COMPANY.
d.
Other orientations require COMPANY authorization.
e.
For double block valves, provision to be made to remove one valve at a time. Spool piece
between valves to be provided to prevent the bolt stuck against the valve body.
Gate Valves

Socket weld or threaded Gate Valves shall be used as the primary shut-off valve for sizes NPS
1-1/2 and smaller if available in pipe class. Flanged Gate Valves shall be used as the primary
shut-off valve in sizes NPS 2 and higher.

Gate Valves shall not be used when there is a requirement for Tight Shut Off (TSO). For TSO,
use either Ball or Plug.

For Piping Classes with socket weld construction, Threaded-end by Socket-end Gate Valves
shall be permitted for use as piping root valves only, in order to provide a threaded connection
for instrumentation or a threaded plug for a drain or process vent.

Gate valves shall comply with the requirement of DGS-1310-014.
Globe Valves

Globe valves shall be used for throttling flow, and shall not be used as the primary shut-off
valve with exception to refrigeration block valves

Globe valves shall not be specified in sizes over NPS 12 for ASME class 150 - 600 PIPING
CLASSES without approval by COMPANY. Butterfly Valves are preferred in sizes NPS 14 and
over. For ASME class 900 and above PIPING CLASSES, Flanged Globe Valves shall be used
as throttling valves.

Globe valves shall comply with the requirement of DGS-1310-015.
Plug Valves

The use of Plug Valves shall be eliminated (where possible) and limited to a temperature of
175ºC.

Flanged Plug Valves with lined ductile iron bodies and plugs shall be used in sizes NPS 1-1/2
and smaller for non-metallic Piping Classes except for Potable Water and Firewater services.

Plug Valves in metallic Piping Classes can be used in chemical services requiring a lined body
and plug. Plug Valves can be used as an alternate to Ball Valves with COMPANY’S approval.

Socket weld Plug Valves shall not be disassembled prior to welding, they shall be supplied with
welded pipe nipples (before mounting and tests) to prevent damage during field welds and
PWHT if required.

Plug valves shall comply with the requirement of DGS-1310-010.
Ball Valves

Ball Valves shall be used for gas and lighter hydrocarbons and for gas tight shut-off purposes
(except where otherwise specified). PTFE seats and seals shall be limited to 180°C. Alternative
soft (resilient) material can be used for temperature up to 200°C. Ball valves shall be fire-safe
design. Electroless Nickel Plating (ENP) / other metallization coating on balls and trim are not
allowed. All trunnion mounted ball valves shall have the trunnion integral with the ball. The
trunnion shall be protected with trunnion wipers to prevent debris entering the trunnion cavity.
All trunnion mounted ball valves sizes NPS 8 and above in sour service shall include secondary
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
seat sealant injection and grease points with heavy duty double check valves and grease
nipples to be fitted with caps as per project pipe classes for the stem, seats and trunnions.
For carbon steel ball valves used in sour service with inconel 625 and Stainless steel trim ,
carbon steel ball Diameter  NPS 6 with inconel 625 / stainless steel overlay are acceptable as
per DGS 0000-002 ‘Material for Sour Environment’ and DGS 6300-003 ‘Welding and NDE of
Pressure Vessels and Heat Exchangers’.

Welded End Valves shall be provided with welded nipples (pup pieces) before assembly and
seat leakage tests to avoid damage to seats from heat and current due to welding pipe directly
to the valve body or PWHT at site.

Ball valves shall comply with the requirement of DGS-1310-012.

Ball Valves shall be full port up to NPS 1 ½ size. TABLE 3 below serves as a guide in selecting
the appropriate ball valve for the service (unless specified otherwise), based on classes to
facilitate the selection.
TABLE 3
BALL VALVE TYPE
NPS
Screwed or
Socket-Weld
Class 150
FLG
Class 300
FLG
Class 600 to
2500 FLG
Class 4500 to
10000 FLG
½ -1½
Floating
Floating (1)
Floating (1)
Floating (1)
Trunnion
2-3
NA
Floating
Floating
Trunnion
Trunnion
4
NA
Floating
Floating
Trunnion
Trunnion
6
NA
Floating
Trunnion
Trunnion
Trunnion
8 - 36
NA
Trunnion
Trunnion
Trunnion
Trunnion
(1) To be used only where special circumstances dictate the use of small flanged valves.
(2) All actuated (motor, pneumatically etc.) valves shall also be trunnion mounted irrespective
of size or rating.
11.3.11
Butterfly Valves

Wafer Butterfly Valves:
Elastomeric lined butterfly valves with suitable seals and O rings shall be used for Potable
Water, Fire Water (Under Ground), Cooling Water and category D fluids, valves bodies and
discs can be either ductile iron or carbon steel. The valves with elastomeric lining shall not be
used for Fire Safe requirement. Wafer type butterfly valves are acceptable only in nonhydrocarbon or utility services.
Wafer Butterfly Valves which do not require gear operators, shall have a locking device on the
lever and shall not have lugs.
Wafer Butterfly Valves requiring gear operators will have lugs which are not tapped but drilled to
accept through bolting.
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
Requirements for gear operator are specified in TABLE2. When gear operators and lugs are
required in sizes other than what is specified in TABLE2, the valve shall be tagged as a
specialty item on the P&ID’s and related drawings.

High Performance Butterfly Valves (Block Valves)
Triple offset metal seated double flanged butterfly valves with fire safe design shall be used for
critical, high temperature fluid, Sulphur service including all flammable hydrocarbons as per API
609 category B and DGS 1310-013 ‘Butterfly Valves’.

Butterfly Valves for Throttling Device
In all hydrocarbon liquid or gas rating 150 ,300 and 600# metal seated butterfly valves shall
be used in diameter  NPS 14 for throttling device.
These valves shall be of Fire Safe Design. Butterfly for Corrosive Non Hydrocarbon Fluid
PTFE lined body and disc with suitable “O” rings and seals can be used for corrosive non
hydrocarbon fluid, Pressure/temperature according to MANUFACTURER’S curve.

General
Butterfly Valves shall not be bolted directly against other valves, fittings or line blinds which
could interfere with travel of the disc. Shafts shall be single piece with anti-blow out design.

11.3.12
Butterfly valves shall comply with the requirement of DGS-1310-013.
Check Valves






Check valves shall be installed wherever a reversal of flow would be operationally objectionable
or create a safety hazard.
Piston or Ball lift Check Valves shall be used in sizes NPS 1-1/2 and smaller. Swing type check
valves shall be used for size NPS 2 to NPS 14 while Double flanged dual plate check valves
shall be used for sizes NPS 16 and above.
Wafer type check valves shall be not be used in hydrocarbon service. Non-Slam type check
valves shall be used where hammering valve closure action due to process/ operating
conditions is expected in addition to the other locations as indicated in the project P&IDs and/or
DGS-0000-021 ‘P&ID Development’.
Butt-Weld Swing Type Check Valves shall be used in all sizes for NPS 2 and above for CLASS
1500 and higher. Dual plate check valves can also be used for NPS 2 and above and CLASS
1500 and higher.
“Non-Slam” Tilting-Disc and “Feather” Type Check Valves should be used where excessive
pressure surges are expected. Swing Check Valves with an external hydraulic dampener
should also be considered. When these valves are required, they shall be tagged as specialty
items on the P&IDs.
Check valves shall comply with the requirement of DGS-1310-011.
11.4
Flanges and Connectors
11.4.1
Forged Flanges
All forged Carbon Steel flanges shall be normalized.
Flanges sizes NPS 24 and smaller for class 2500 and lower flange ratings shall be per ASME B16.5.
Flanges larger than NPS 24 through NPS 60 shall be manufactured per ASME B16.47 Series A.
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
Flanges larger than NPS 60 and flanges not covered by ASME B16.47 shall be designed per ASME
sec. VIII Division 1. VENDOR shall supply dimensional drawing for COMPANY / CONTRACTOR
approval
Flange construction shall match the pipe fitting (by size) associated in the appropriate Piping Class,
such as socket weld fittings require socket weld flanges, threaded fittings require threaded flanges
and butt-weld fittings require weld neck flanges. Slip-On flanges should not be used in place of weld
neck flanges unless approved by the COMPANY.
Slip-On reducing flanges shall not be used to eliminate reducers. Carbon steel lap joint flanges are
not permitted in stainless steel Piping Classes.
Jack screw arrangement shall be required for spectacle blinds sizes 6” and above.
11.4.2
11.4.3
Threaded Flanges
a.
Threaded flanges shall be used in PIPING CLASSES allowing threaded fittings (some utility
services), and only in the same sizes as the threaded fittings.
b.
For PIPING CLASSES with socket weld construction, Threaded Reducing Flanges shall only be
permitted downstream of flanged piping root valves, in order to provide a threaded connection
for instrumentation.
Weld-Neck Flanges
Weld-neck flanges shall be specified with the bore to match the pipe inside diameter.
11.4.4
Raised Face (RF) Flanges
Raised Face (RF) flanges shall be used for all metallic piping classes 150# - 300#.
All non-metallic PIPING CLASSES (RTRP and PVC) or classes with Cast Iron/Bronze valves,
flanges shall be Flat Faced (FF).
11.4.5
“Grayloc” Type Connectors
“Grayloc” Type Connectors shall be used for 2500 # and above ratings.
Hub connectors shall be complete with two hubs, a clamp, a seal ring and bolting. All hub connector
components shall be designed and their performance warranted by the same Manufacturer.
11.4.6
Flange Finish

11.4.7
The flange facing finish shall be as per ASME B16.5 / ASME B16.47.
Lap Joint Stub
Lap Joint Stub Ends shall not be used.
11.4.8
RTJ Flanges
Ring Type Joint (RTJ) flanges shall be used for metallic piping classes 600# and higher. RTJ
Flanges shall be harder than RTJ gaskets, 20 HB points minimum.
11.4.9
11.4.10
Flange Construction

For sour service, flange construction shall be butt welding neck only. Socket weld and threaded
flanges shall not be used.

Flanges mating to cast iron equipment and valves shall be flat faced and used with full face
gaskets.
Orifice Flanges
Orifice Flanges shall be supplied in accordance with ASME B16.36 supplied in pairs complete with
jackscrews but without orifice plates, gaskets and bolts. Quantities shall indicate sets, not individual
flanges.
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
Pressure tap holes shall be NPS ½ socket weld connection shall be limited to sour service in
accordance with ASME B16.11. For other non-sour services NPS ½ threaded tap holes shall be
used.
11.4.11
Spectacle blinds
Spectacle blinds/spacer/blinds shall be in accordance with ASME B16.48. Spacers and blinds shall
be used for sizes larger than NPS 12, 12, 8 and 6 for class 150#, class 300#, class 600# and class
900# respectively. Refer DGS 0000-021 ’P&ID Development’ for guidelines. Line blinds facing shall
be in accordance with piping class. Line blinds dimensions for size NPS 26 and above to suit MSSSP-44 or ASME B16.47 series A.
11.5
Gaskets
Where RTJ gaskets are used, they shall be of the oval ring type and the hardness shall be 20HB
point minimum less than that of the flange groove hardness.
Spiral wound graphite gaskets shall be used in Class 150# and 300# have an inner and centering
ring, unless otherwise specified in the individual Piping Classes. RTJ gaskets shall be used for
Class 600# and greater.
For non-metallic piping, gaskets shall be non-confined non-metallic in accordance with ASME
B16.21.

For Reinforced Thermosetting Resin Pipe (RTRP) the gasket material shall be specified by the
RTRP MANUFACTURER for the service conditions.

Non-metallic gaskets shall be limited to the maximum temperature as specified by the
MANUFACTURER.
Asbestos gaskets or asbestos filled gaskets shall not be used.
11.6
Bolting
The minimum bolt diameter to be used shall be NPS ½. Unless indicated otherwise, bolt diameters
shall be in accordance with ASME/ B16.5 (for flanges NPS 24 & smaller), and ASME B16.47 Series
A & MSS SP 44 (for flanges 26 inches & larger).
Bolt lengths shall be calculated in accordance with ASME B16.5 and ASME B16.47. Where bolt
tensioning is required, bolt lengths (Refer DGS 1300-160 ‘Bolt Torquing /Tensioning Procedure for
Flanged Connections’) shall include an additional length of one bolt diameter to facilitate the use of
bolt tensioning equipment. Material test certificate shall be provided addressing all testing details
and values equivalent to TAKECOAT-1000 and all tools for bolts torque tightening shall be used as
recommended by manufacturer to avoid coating damage. In case of coating damage, manufacturer
recommendations shall be submitted for repair.
External fasteners (bolts, studs and nuts) shall be coated with a fluorocarbon polymer system such
as TAKECOAT-1000 or equivalent. Screw threads shall be unified coarse threads in accordance with
ASME B1.1 having class 2A for bolts and class 2B for nuts.
Screw threads in sizes 1-1/8” and larger shall be unified 8 threads.
Nuts for bolts shall be heavy hexagonal semi-finished.
Machine bolts shall not be used without COMPANY’S approval.
Stud bolt length measurement shall be based on the effective thread length.
Bolt length shall be specified in 5 mm increments.
For bolt tensioning equipment and requirements, refer to DGS 1300-160 ‘Bolt Torquing /Tensioning
Procedure for Flanged Connections’.
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
Bolting for sour services shall follow the requirements of NACE MR01-75 / ISO 15156, The stud
bolts and nuts shall be ASTM A 193 Grade B7M and ASTM A 194 Grade 2HM only for bolts
exposed directly to the sour process fluid, insulated, equipped with flange protectors or otherwise
denied direct exposure to the atmosphere.
All other bolting in sour services, generally all aboveground piping with uninsulated flanges, shall be
stud bolts and nuts in accordance with ASTM A 193 Grade B7 and ASTM A 194 Grade 2H.
11.7
Fittings
Socket welding fittings shall be used for NPS 1-1/2 and smaller in ASME class 150, 300 and 600
non Sour Service for general services. All forged steel fittings shall be normalized.
Butt-welding fittings shall generally be used for NPS 2 and larger, in ASME Class 150, 300 and 600
non Sour Service and all sizes (NPS 1/2 and higher) in class 900 and above.
Butt-welding fittings shall be used for all ASME classes (class 150 and above) in Sour Service.
Socket weld fittings shall not be used in SOUR piping services and in vendor package piping.
Use short radius elbows only where specifically authorized by COMPANY.
11.8
Pipe bends
Pipe bends shall not be used diam. < NPS 11/2. For size diam. > NPS 2 pipe bends may be used
with COMPANY’S approval. When allowed, bends may be used in place of fittings and shall be
fabricated to the requirements of DGS 1300-185 ‘Fabrication, Handling and Installation of Process
and Utility Piping’.
11.9
Miter bends
Miter Bends shall not be used.
11.10
Steam traps
COMPANY recommends steam traps with flanged ends for maintenance reasons. However, end
connections shall be determined during detailed design by CONTRACTOR/COMPANY. Steam
traps for steam header drip legs and steam tracing shall have socket weld ends.
Steam traps shall be provided with an integral (permanent) strainer. For process steam traps that
cannot be supplied with an integral strainer, a permanent Y-strainer shall be provided directly
upstream of the trap.
Thermodynamic Steam Traps shall be used with steam header drip legs and for steam-tracing
manifolds.
Suitable Steam traps based on design conditions for process equipment shall be designed and
selected on an individual basis.
11.11
Underground protection
Buried steel piping shall be externally protected in accordance with DGS 1470-002 ‘Polyurethane
Coating for Bend Valves and Fittings’ /DGS 1470-003 ‘Three Layer Polyethylene Coating System’
and DGS 1674-001 ‘Design - Installation, Commissioning and Monitoring of Cathodic Protection for
Plant Facilities’.
11.12
Insulation
Insulation of piping, including requirements for valves and flanges, shall be in accordance with the
applicable DGS 6500-010 ‘Hot Insulation for Piping & Equipment’, DGS 6500-020 ‘Cold Insulation
for Piping and Equipment’ and DGS 6000-003 ‘Acoustic Insulation for Pipe, Valves and Flanges’.
DGS 1300 - 010 REV 2
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
11.13
Branch connections
11.13.1
General
Branch connections shall be as defined in the Branch Connection Tables in Appendix II of this
specification. The basis for the development of these Tables and additional branches not covered in
the Tables are express as follows:
11.13.2

Same size branches shall be made with a straight tee with end connections to match the
PIPING CLASS.

Socket weld branches in socket weld piping and threaded branches in threaded piping shall be
made with reducing tees.

Butt-weld branches in butt-weld piping shall be made with either un-reinforced pipe to pipe
stub-in connections or weldolets. When an un-reinforced pipe to pipe connection does not
conform to the pressure requirements as defined in ASME B31.3, reducing tees or weldolets
shall be used instead of adding a reinforcing pad.

Butt welding tee fittings should be used in severe cyclic service (as defined in ASME B31.3).

The branch Tables represent minimum requirements for branches for pressure containment.
Branch connection should be upgraded on a case-by-case basis to satisfy pipe stress
requirements.
Reducing branches
Reducing branches at elbows on the header pipe shall be kept to a minimum and shall be made with
an “O-Let” type fitting.
11.13.3
Component Selection
Branch connections are shown in Appendix II for each PIPING CLASS and identified by the following
nomenclature:
CODE
DGS 1300 - 010 REV 2
EXPLANATION OF CHARACTERS
A
Equal Tee
B
Reducing Tee
C
Branch Fitting (Sockolet)
D
Pipe to Pipe (Un-reinforced Stub-On)
E
Branch Fitting (O-Let)
F
Equal Tee with Reducer
G
Reducing Tee with Reducer
H
Pipe to pipe without reinforced pad
J
Pipe to pipe without reinforced pad (header with heavy w.t)
K
Long Welding Neck
L
Reducing saddle
T
Branch Fitting (Threadolet)
Rev.
DGS
1300
010
2
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ABU DHABI GAS INDUSTRIES LTD. (GASCO)
PIPING SYSTEMS (PIPING CLASSES)
11.13.4
Piping Assembly Details
In piping design standard drawings STD-1300-001, Piping Assembly Details are illustrated for
general instrument, vent and drain connections on piping. The details in STD 1300 001 are
standard details to be used with the materials specified in the Piping Classes. Whenever there are
differences between the standard Piping Assembly Details and the materials contained within the
Piping Classes, the general notes in the specific Piping Class will clarify the revised piping
configuration.
The basic concept for the Piping Assembly Details is as follows:

Pressure Taps connections shall be NPS 3/4 valved.

Temperature connections shall be NPS 1½ flanged and are not permitted on NPS 3 and smaller
piping.

Drains and process vents shall be NPS 3/4 valved connections.

Hydrostatic vents shall be NPS 3/4 unvalved connections. Threadolets with threaded plugs
shall be used on butt welded piping, classes 150 - 300# - 600# Non Sour Service.

Orifice flange shall be in full compliance with ASME/ B16.36 size connection tapped NPT.
Orifice taps to be rotated 45 degrees from vertical axis and each tap shall be 90 degrees apart.
The extra tap on the orifice flange not used shall be plugged, and seal welded.

The length of the pipe nipple shall be 100 mm long, with exception of pipe nipples for orifice
flanges 150 mm long.
12.
FABRICATION
12.1
Fabrication/installation
Fabrication and installation of Piping shall be in accordance with DGS 1300-185 ‘Fabrication,
Handling and Installation of Process and Utility Piping’.
12.2
Material Traceability
Material Traceability for shop and field fabricated piping shall be in accordance with DGS 1300-190
‘Traceability of Shop and Field Fabrication Piping Materials’.
12.3
Seal Welding
All threaded connections shall be seal welded. Threaded instrument connections are allowed only
downstream of a piping root valve and shall be seal welded. Hydrostatic vent and drain caps and
plugs seal welded after hydro testing and requiring PWHT due to process reasons shall be
arranged.
12.4
Postweld Heat Treatment
Postweld Heat Treatment shall be in accordance with the requirements as per ASME B31.3 and
additional requirements of DGS 6300-001 ‘Welding and NDE of Piping System‘ and DGS 0000-002
‘Material for Sour Environment’ as applicable.
Piping Classes that have been designed for services that require Postweld Heat Treatment shall be
identified in the Piping Class Summary and general notes of the individual piping classes.
Welds requiring Postweld Heat Treatment shall be prefabricated as much as possible, minimizing
field welds.
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PIPING SYSTEMS (PIPING CLASSES)
12.5
Coating and Lining Requirement
12.5.1
Galvanizing
The galvanizing for pipes and fitting shall be as per ASTM A153 and DGS-1300-175.
They shall be hot dip galvanized both inside and outside. Welds shall not be allowed after
galvanization.
12.5.2
Aluminizing
The hot spray aluminum coating shall be applied by arc spray method with minimum of two crossing
passes per layer. Each layer is to be a minimum 3 mil thick. The thickness of the completed
aluminum coating shall be from 10 mil minimum to 15 mil maximum (250 to 375 micrometers). (1mil
= 0.0254mm)
12.5.3
Fusion bounded Epoxy (FBE) Coating
The pipe and fitting shall be FBE coated as per API 5L7.
COMPANY approved project specification of FBE coating shall be followed, as a minimum FBE
coating thickness shall be as below,
12.5.4
Minimum DFT thickness
375 micrometers
Nominal (target) DFT thickness
625 micrometers
Maximum DFT thickness
1250 micrometers
Refractory Lining
Refractory lining for internal surfaces of carbon steel pipe and fittings shall be as per DGS-6531-020
(Materials, Installation and Testing Requirements for Refractory Systems) or project specific
refractory lining details shall be followed upon agreement with COMPANY.
12.5.5
Glass Flake Resin (GFR) Lining
The pipe and fittings shall be internally lined with minimum 1.0 mm thick coating of Glass Flake
Resin (polyester or epoxy). Welding shall not be allowed after internal coating.
12.5.6
Polypropylene (PP) Lining
The pipe and fittings shall be internally lined with Polypropylene resin in accordance with ASTM
D4101. Minimum physical properties and lining thickness shall be in accordance with ASTM F1545.
12.5.7
Polyvinylidene fluoride (PVDF) Lining
The pipe and fittings shall be internally lined with Polyvinylidene fluoride in accordance with ASTM
D3222. Minimum physical properties and lining thickness shall be in accordance with ASTM F1545.
12.5.8
Cement Lining
Unless a greater thickness has been specified by the COMPANY, the lining thickness after curing
shall be in accordance with BS EN 10298.
Pipe DN 650 (NPS 26) and larger shall have butt welding ends in accordance with ASME B16.25.
Pipe DN 600 (NPS 24) and smaller sizes shall have plain ends, with a sleeve coupling externally
welded to one end.
All fittings (bends, tees, reducers etc.) shall have 150 mm (NPS 6) long pup piece at each ends
either bought out as such or pre-fabricated prior to cement lining. Fittings shall have sleeve
couplings externally welded to both ends. Sleeves shall be either loose supplied or shall be part of
the pre-fabricated fittings as specified in the material requisition.
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Flanges shall be ASME rating class 150, raised face, except where flat face flanges are required for
replacement in existing installations.
Slip-on flanges shall be installed for pipe sizes up to DN 600 (NPS 24). For pipe sizes DN 650 (NPS
26) and larger, welding neck flanges shall be used.
13.
NON METALLIC PIPING
13.1
Fiber Reinforced Plastic (FRP) Piping
GRE piping design, materials and installation shall be in accordance with DGS 1470-009
‘Requirements for Fiber Reinforced Plastic (FRP) Pipes and Fittings’.

For GRE pipes up to NPS 24, a minimum design pressure of 20 Barg shall be considered
irrespective of actual operating pressure.

If the pressure is more than 20 barg then GRVE and GRUP pipes should NOT be used.

For chlorination lines the recommended RTR material is Glass-fiber Reinforced Vinylester
(GRVE).

Following philosophy shall be followed for selection of GRE, GRV and GRP pipes.
a. Max Design Temperature - GRE
- 110°C
b. Max Design Temperature - GRVE - 100°C
c.
Max Design Temperature - GRUP - 70°C
Size Range for GRE/GRUP and GRVE pipes Material
13.2
Size Range
Maximum Pressure Rating
GRE
25 to 1200 mm
Up to 50 barg depending on the diameter, temperature, pipe
routing & Installation
GRVE
25 to 4000 mm
Up to 20 barg depending on the diameter, temperature & the
actual operating conditions
GRUP
25 to 4000 mm
Up to 20 barg depending on the diameter, temperature & the
actual operating conditions
Spoolable Fibre-Reinforced Composite Pipes
To reduce the installation time and to avoid joints in FRP Piping the Spoolable Fibre-Reinforced
Composite Plastic pipes (S-FRP) can be considered. For the existing FRP pipe classes
(GRE/GRUP/GRVE), spoolable material can be used for long runs in buried installations.
The option to use S-FRP pipes shall consider factors like the length of the installation and the space
availability. Contractor shall obtain COMPNANY approval for using Spoolable Fibre-reinforced
composite pipe in lieu of FRP pipes.
The spoolable fibre-reinforced composite pipe materials (S-FRP) are not covered under piping
classes in Appendix-II of this DGS. This shall be detailed out based on project specific requirement
with COMPANY approval.
13.3
HDPE Piping
HDPE Piping shall be in accordance with ASTM D3350 and dimensional measurement shall be in
accordance with ASTM D2122.
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PIPING SYSTEMS (PIPING CLASSES)
13.4
UPVC Piping
UPVC Piping shall be in accordance with ASTM D1784. Socket type pipe fitting shall be as per
ASTM D2466 or ASTM D2467.
13.5
CPVC Piping
CPVC Piping shall be in accordance with ASTM D1784. For socket type pipe shall be as per ASTM
F441 and pipe fitting shall be as per ASTM F438 or ASTM F439.
14.
FIELD PRESSURE TESTING
Field Pressure Testing of Piping shall be in accordance with DGS 1300-030 ‘Process and Utility
Field/Shop Pressure Testing’.
All ESD, TSO and Tie-in valves shall be pressure tested at site as per API-598 for shell Low
pressure Closure and High Pressure Closure tests, with the exception that resilient-seated valves
shall not be tested for High Pressure Closure tests due to risk of permanent deformation in the
resilient material.
Test Pressure and duration shall be as per API-598 requirements while leakage rate shall be
according to closure class defined for that valve.
15.
APPENDICES
Appendix I – Piping Classes Summary
Summary of all 150 piping classes with base material, the corrosion allowance, temperature
pressure limits, fluid service, piping size range and main isolation valves used with its trim material.
Appendix II – Piping Classes & Branch Connection Details
This Appendix provides the index of 150 piping classes followed by the detailed individual piping
class and the branching table. The index is linked the individual piping classes, click on the required
piping class will guide to reach to that piping class. The index also provides the broad classification
of the piping classes as they derived.
Appendix III – Consolidated Pipe Classes Cross Reference Index
This Appendix is in two parts. Part 1 provides the correlation of 150 piping classes with ASAB and
RUWAIS piping classes and Part 2 with HABSHAN and BU HASA.
The correlation of new DGS piping class with the existing piping plant class as provided under the
Appendix III shall be verified during the project execution. Any discrepancy shall be highlighted to
COMPANY for approval to proceed.
Appendix IV – Area wise Pipe Classes Cross Reference Index
The Appendix IV provides the correlation between the applicable DGS piping classes and existing
plant piping classes. It is divided in four parts. First part is for ASAB, part two is Bu HASA, part three
is HABSHAN and part four is RUWAIS.
DGS 1300 - 010 REV 2