ICS 23.
CCS J
National Standard of the People’s Republic of China
GB/T 20801.5-2025
Pressure piping code – Part 5 : Hydrogen piping and pipelines
压力管道规范
第5部分:氢用管道
(English translation)
Issue date: 2025-10-31 Implementation date: 2026-05
Issued by the State Administration for Market Regulation of the People's Republic of China
the Standardization Administration of the People's Republic of China
Pressure piping code Part 5 : Hydrogen piping and pipelines
1 Scope
1.1 This document specifies the basic requirements, materials, design and calculation, fabrication and installation, inspection and test, and safety protection of hydrogen piping and pipelines. For gaseous hydrogen transmission pipelines, it stipulates the technical requirements for commissioning, use and maintenance, as well as the emergency maintenance; and for gaseous hydrogen utility pipelines, it also stipulates the technical requirements for safe operation and maintenance.
Note 1: Hydrogen piping and pipelines refer to various pipelines for transmitting hydrogen medium, including gaseous hydrogen industrial piping, gaseous hydrogen transmission pipelines and gaseous hydrogen utility pipelines, as well as liquid hydrogen pipelines.
Note 2: The parts extending into the boundary of hydrogen production plants, hydrogen stations, hydrogen supply stations, city gas gate stations, gas storage depots, gas power plants and other factories, as well as the hydrogen pipelines connecting factories, shall comply with the requirements of gaseous hydrogen transmission pipelines or gaseous hydrogen industrial piping.
1.2 This document applies to gaseous hydrogen piping and pipelines with maximum working pressure greater than or equal to 0.1 MPa (gauge pressure) and nominal diameter greater than or equal to DN50. Other gaseous hydrogen piping and pipelines are subject to reference.
1.3 For the gaseous hydrogen industrial piping, gaseous hydrogen transmission pipelines and gaseous hydrogen utility pipelines in this document , the following conditions apply:
a) gaseous hydrogen industrial piping: transmitting industrial hydrogen medium, with a design pressure less than or equal to 41 MPa.
b) gaseous hydrogen transmission pipelines: onshore pipelines transmitting a hydrogen volume fraction greater than or equal to 3%, with a design pressure less than or equal to 12 MPa and a design temperature less than or equal to 150 °C.
c) gaseous hydrogen utility pipelines:
1) the volume content of hydrogen shall be larger than 60%, and the maximum working pressure shall be less than or equal to 1.6 MPa;
2) the volume content of hydrogen shall be larger than 3% less than or equal to 60%, and the maximum working pressure shall be larger than 0.4MPa and less than or equal to 4.0 MPa;
Note: See Annex A for the construction method of gaseous hydrogen industrial piping with design pressure greater than 41MPa and less than 100MPa, Annex B for the construction method of gaseous hydrogen transmission pipelines with design pressure greater than 12MPa and less than 21MPa, and Annex C for the construction method of cryogenie hydrogen and liquid hydrogen piping.
1.4 This document does not apply to the following pipings:
a) piping of military equipment and nuclear facilities;
b) piping for oceans, offshore facilities and mines;
c) piping for petroleum, natural gas, geothermal exploration and extraction installations, as well as oil and gas field gathering and transmission pipelines;
d) piping on mobile equipment such as railway locomotives, automobiles, ships and aerospace vehicles;
e) internal piping of boilers, pressure vessels and heating furnaces as well as external piping orifices of equipment;
f) piping of equipment body, including internal piping of pumps and compressors (excluding pipes connecting multiple stages on-site), steam turbines, gas turbines, internal combustion engines, packaged refrigeration units, quick-freezing devices, and other fluid conveying or processing equipment, as well as external piping orifice of equipment.
1.5 For the gaseous hydrogen transmission pipelines and gaseous hydrogen utility pipelines in this document , the following conditions apply:
a) For gaseous hydrogen transmission pipelines, the following conditions do not apply:
1) The pipeline for transmitting hydrogen-containing mixture designed according to GB/T 34275-2024 or GB 50251, and it has been proved by engineering analysis or test that it will not have any adverse effect on the system integrity of the pipeline;
2) The gaseous hydrogen transmission pipelines whose preliminary design has been completed before the implementation of this document, and the technical compliance of the pipeline under construction and in service has been traced and evaluated.
Note: The time of completing the preliminary design refers to the date of obtaining the written reply from the construction unit.
b) For gaseous hydrogen utility pipelines, the following conditions do not apply:
1) Piping in hydrogen plant and station;
2) Internal gaseous hydrogen piping and pipelines for industrial users (divided by plant boundaries);
c) Internal gaseous hydrogen piping (divided by introducing pipe valve) for commercial and residential users;
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 231.1 Metallic materials - Brinell hardness test
GB/T 713.2 Steel plate, sheet and strip for pressure equipments - Part 2: Non-alloy and alloy steel with specified temperature properties
GB/T 897 Double end studs - bm=1d
GB/T 898 Double end studs - bm=1.25d
GB/T 1031 Geometrical product specifications(GPS) - Surface texture: Profile method - Surface roughness parameters and their values
GB/T 1047 Pipework components-Definition and selection of nominal size
GB/T 1048 Pipework components-Definition and selection of nominal pressure
GB/T 3087 Seamless steel tubes and pipes for low and medium pressure boiler
GB/T 3091 Welded steel pipes for low pressure fluid delivery
GB/T 4237 Hot rolled stainless steel plate,sheet and strip
GB/T 4622.1 Spiral wound gaskets for pipe flanges - Part 1: PN designated
GB/T 4622.2 Spiral wound gaskets for pipe flanges - Part 2: Class designated
GB/T 5310 Seamless steel tubes and pipes for high pressure boiler
GB/T 5782 Hexagon head bolts
GB/T 6170 Hexagon nuts, style
GB/T 6175 Hexagon nuts, style
GB/T 6394 Determination of estimating the average grain size of metal
GB/T 8163 Seamless steel pipes for liquid service
GB/T 9065.1 Hydraulic hose fittings - Part 1: Hose fittings with O-ring face seal ends
GB/T 9065.2 Connections for hydraulic fluid power - Hose fittings - Part 2: 24° cone connectors
GB/T 9065.5 Connections for hydraulic fluid power and general use - Hose fittings - Part 5: Hose fittings with 37° degree flared ends
GB/T 9124.1 Steel pipe flanges - Part 1: PN designated
GB/T 9124.2 Steel pipe flanges - Part 2: Class designated
GB/T 9125.1 Fasteners for steel pipe flange joints - Part 1: PN designated
GB/T 9125.2 Fasteners for steel pipe flange joints - Part 2: Class designated
GB/T 9126.1 Non-metallic flat gaskets for pipe flanges - Part 1: PN designated
GB/T 9126.2 Non-metallic flat gaskets for pipe flanges - Part 2: Class designated
GB/T 9128.1 Metallic ring joint gaskets for steel pipe flanges - Part 1: PN designated
GB/T 9128.2 Metallic ring joint gaskets for steel pipe flanges - Part 2: Class designated
GB/T 9711 Petroleum and natural gas industries - Steel pipe for pipeline transportation systems
GB/T 9948 Seamless steel tubes for petroleum cracking
GB/T 10561 Determination of content of nonmetallic inclusions in steel - Micrographic method using standard diagrams
GB/T 12220 Induatrial valves - Marking
GB/T 12221 Metal valves - Face to face,end to end,center to face and center to end dimensions
GB/T 12224 General requirements for industrial steel valves
GB/T 12232 General purpose industrial valves - Flanged iron gate valves
GB/T 12234 Bolted bonnet steel gate valves for petroleum and natural gas industries
GB/T 12235 Steel globe valves and lift check valve for petroleum, petrochemical and allied industries
GB/T 12236 Steel swing check valve for petroleum, petrochemical and allied industries
GB/T 12237 Steel ball valves for petroleum, petrochemical and allied industries
GB/T 12238 Flanged and wafer resilient seal butterfly valves
GB/T 12239 Industrial valves - Diaphragm valves made of metallic materials
GB/T 12241 Safety valves - General requirements
GB/T 12243 Spring loaded safety valves
GB/T 12246 Pilot operated pressure reducing valves
GB/T 12459-2017 Steel buttwelding pipe fittings - Types and parameter
GB/T 12771 Welded stainless steel pipes for fluid transport
GB/T 12777 General specification for metal bellows expansion joints
GB/T 13401 Steel buttwelding piping fittings - Technical specification
GB/T 13402 Large diameter steel pipe flanges
GB/T 13403 Gaskets for large-diameter steel pipe flanges
GB/T 13404 Non-metallic PTFE envelope gaskets for pipe flanges
GB/T 13927 Industrial valves - Pressure testing
GB/T 14383 Forged fittings, socket-welding and threaded
GB/T 14976 Seamless stainless steel pipes for fluid transport
GB/T 15558.1 Buried polyethylene(PE) piping systems for the supply of gaseous fuels - Part 1: General
GB/T 15558.2 Buried polyethylene(PE) piping systems for the supply of gaseous fuels - Part 2: Pipes
GB/T 15558.3 Buried polyethylene(PE) piping systems for the supply of gaseous fuels - Part 3: Fittings
GB/T 15558.4 Buried polyethylene(PE) piping systems for the supply of gaseous fuels - Part 4: Valves
GB/T 15558.5 Buried polyethylene(PE) piping systems for the supply of gaseous fuels - Part 5: Fitness for purpose of the system
GB/T 17116.1 Pipe supports and hangers - Part 1: Technical specification
GB/T 17116.2 Pipe supports and hangers - Part 2: Pipe attachments
GB/T 17116.3 Pipe supports and hangers - Part 3: Middle connection attachments and building structure attachments
GB/T 17185 Steel flanged fittings
GB/T 17186.1 Calculation methods for the pipe flange joints - Part 1: Calculation method satisfies both strength and rigidity requirements
GB/T 17394 (all parts) Metallic materials - Leeb hardness test
GB/T 17395 Dimensions, shapes, masses and tolerances of steel tubes
GB 17820 Natural gas
GB/T 18984 Seamless steel tubes for low-temperature-service piping
GB/T 19326 Forged branch outlet fittings
GB/T 19675.1 Reinforced flexible graphite gaskets for pipe flanges - Part 1: PN designated
GB/T 19675.2 Reinforced flexible graphite gaskets for pipe flanges - Part 2: Class designated
GB/T 20674.1 Plastics pipes and fittings. Equipment for fusion jointing polyethylene systems. Part 1: Butt fusion
GB/T 20674.2 Plastics pipes and fittings - Equipment for fusion jointing polyethylene systems - Part 2: EIectrofusion
GB/T 20801.1-2025 Pressure piping code - Part 1: Industrial piping
GB/T 26255 Steel-plastic-transition fittings for polyethylene(PE) piping systems for the supply of gaseous fuels
GB/T 26480 Valve inspection and testing
GB/T 26481 Industrial valves test for fugitive emissions
GB/T 28708 Specification for size selection of seamless and welded steel pipe used in piping engineering
GB/T 29168.1 Petroleum and natural gas industries - Induction bends, fittings and flanges for pipeline transportation systems - Part 1: Induction bends
GB/T 29168.2 Petroleum and natural gas industries - Bends, fittings and flanges for pipeline transportation systems - Part 2: Fittings
GB/T 29168.3 Petroleum and natural gas industries - Induction bends, fittings and flanges for pipeline transportation systems - Part 3: Flanges
GB/T 29729-2022 Essential requirements for the safety of hydrogen systems
GB/T 31480 Materials for high vacuum multilayer insulation of cryogenic vessel
GB 32167 Oil and gas pipeline integrity management specification
GB/T 32294 Forged unions, socket-welding and threaded
GB/T 34275-2024 Pressure piping code - Transmission pipeline
GB/T 34474.1 Determination of banded structure of steel - Part 1: Micrographic method using standards diagrams
GB/T 34542.2 Determination of banded structure of steel - Part 2: Quantitative method
GB/T 35990 Metal bellows expansion joints for pressure piping
GB/T 36701 Guideline for defect repair of buried steel pipelines
GB/T 38343 Technical specification for flange joints installation
GB/T 38942-2020 Pressure piping code - Utility piping
GB/T 39245.1 Grooved metal gaskets with covering layers for pipe flanges - Part 1: PN designated
GB/T 39245.2 Grooved metal gaskets with covering layers for pipe flanges - Part 2: Class designated
GB/T 40079 Classification system and qualification procedures for fugitive emission type testing of valves
GB/T 43922 Inspection and evaluation of in-service polyethylene gas pipeline
GB 50028 Code for design of city gas engineering
GB 50032 Code for seismic design of outdoor water supply sewerage gas and heating engineering
GB 50156-2021 Technical standard of fuelling station
GB 50160-2008 Fire prevention code of petrochemical enterprise design
GB 50177 Design code for hydrogen station
GB/T 50470 Seismic technical code for oil and gas transmission pipeline engineering
GB/T 50493 Standard for design of combustible gas and toxic gas detection and alarm for petrochemical industry
GB 50516-2010 Technical code for bydrogen fuelling station
GB 50683 Technical code for hydrogen fuelling station
GB/T 50698 Standard for AC interference mitigation of buried steel pipelines
GB 50991 Technical standard for DC interference mitigation of buried steel pipeline
GB/T 51098 Code for planning of city gas
GB 51283-2020 Fire protection standard for engineering design of fine chemical enterprise
GB/T 51474 Standard for safety of operation, maintenance and rush-repair of city gas facilities
GB 55002 General code for seismic precaution of buildings and municipal engineering
GB 55009 Project code for gas engineering
CJJ/T 49 Technical standard for stray current corrosion protection in metro
CJJ 63 Technical standard for polyethylene (PE) gaseous fuel pipeline engineering
CJJ 95 Technical specification for external corrosion control of buried steel pipeline for city gas
CJJ/T 153 Standard for city gas signs
CJJ/T 215 Technical specification for leak detection of city gas piping system
CJJ/T 250 Technical specification for crossing and aerial crossing engineering of city gas pipeline
HG/T 20537.3 Chemical apparatus of austenitic stainless steel welded pipe technical requirements
HG/T 20537.4 Chemical apparatus of austenitic stainless steel welded pipe technology requirements of large diameter
HG/T 20553 Selection series of steel pipe size for chemical piping
HG/T 20592 Steel pipe flanges (PN designated)
HG/T 20606 Non-metallic flat gaskets for use with steel pipe flanges (PN designated)
HG/T 20607 PTFE envelope gaskets for use with steel pipe flanges (PN designated)
HG/T 20609 Metal jacketed gaskets for use with steel pipe flanges (PN designated)
HG/T 20610 Spiral wound gaskets for use with steel pipe flanges (PN designated)
HG/T 20611 Covered serrated metal gaskets for use with steel pipe flanges (PN designated)
HG/T 20612 Metallic ring joint gaskets for use with steel pipe flanges (PN designated)
HG/T 20613 Bolting for use with steel pipe flanges (PN designated)
HG/T 20614 Specification for selection of steel pipe flanges,gaskets and bolting (PN designated)
HG/T 20615 Steel pipe flanges (Class designated)
HG/T 20623 Large diameter steel pipe flanges (PN designated)
HG/T 20627 Non-metallic flat gaskets for use with steel pipe flanges (Class designated)
HG/T 20628 PTFE envelope gaskets for use with steel pipe flanges (Class designated)
HG/T 20630 Metal jacketed gaskets for use with steel pipe flanges (Class designated)
HG/T 20631 Spiral wound gaskets for use with steel pipe flanges (Class designated)
HG/T 20632 Covered serrated metal gaskets for use with steel pipe flanges (Class designated)
HG/T 20633 Metallic ring joint gaskets for use with steel pipe flanges (Class designated)
HG/T 20634 Bolting for use with steel pipe flanges (Class designated)
HG/T 20635 Specification for selection of steel pipe flanges,gaskets and bolting (Class designated)
HG/T 21547 Paddle blank, Paddle spacer, Figure-8 blank for piping system
JB/T 74 Steel pipe flanges - Types and parameters
JB/T 75 Steel pipe flanges - Types and parameters
JB/T 79 Integral steel flanges
JB/T 81 Slip-on-welding plate steel pipe flanges
JB/T 82 Steel pipe welding neck flanges
JB/T 83 Loose plate steel pipe flanges with weld-on collar
JB/T 84 Loose plate flange with weld-neck collar
JB/T 85 Steel pipe welding neck flanges
JB/T 6439 Methods of magnetic examination for valves
JB/T 6440 Methods of radiographic examination for steel castings valves
JB/T 6899 Firetest for valves
JB/T 6902-2008 Methods for liquid penetrant examination of valves
JB/T 6903-2008 Methods for ultrasonic examination of steel gorgings for valves
JB/T 7746 Compact steel valves
JB/T 7747 Needle valve
JB/T 7927-2014 Valve cast steel visual quality requirements
JB/T 8937 Wafer type check valve
NB/T 47008 Carbon and alloy steel forgings for pressure equipment
NB/T 47009 Alloy steel forgings for low temperature pressure equipment
NB/T 47010 Stainless and heat-resisting steel forgings for pressure equipment
NB/T 47013.2 Nondestructive testing of pressure equipments - Part 2: Radiographic testing
NB/T 47013.15 Nondestructive testing of pressure equipments - Part 15: Phased-array ultrasonic testing
NB/T 47014 Welding procedure qualification for pressure equipments
SH/T 3401 Nonmetallic flat gaskets for steel pipe flanges in petrochemical industry
SH/T 3402 Polytetrafluoroethylene envelope gaskets for steel pipe flanges in petrochemical industry
SH/T 3403 Metallic ring joint gaskets for steel pipe flanges in petrochemical industry
SH/T 3404 Fasteners for steel pipe flanges in petrochemical industry
SH/T 3405 Series of steel pipe size in petrochemical industry
SH/T 3406 Specification for steel pipe flanges in petrochemical engineering
SH/T 3407 Spiral wound gaskets for steel pipe flanges in petrochemical industry
SH/T 3408 Specification for steel butt-welding pipe fittings in petrochemical engineering
SH/T 3410 Forged steel socket-welded and threaded fittings in petrochemical industry
SH/T 3419 Steel swaged nipples in petrochemical industry
SH/T 3424 Forged steel socket-welding and threaded unions in petrochemical engineering
SH/T 3425 Steel line blanks in petrochemical engineering
SH/T 3518 Specification for valves inspection, testing and installation in petrochemical industry
SY/T 7033 Specification for emergency repair of oil and gas steel pipelines
TSG D7003 Periodical Inspection Regulation for Long Distance Pipeline
TSG D7005 Periodic Inspection Regulation for Industrial Pressure Piping
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 20801.1-2025, GB/T 34275-2024, GB/T 38942-2020 and the following apply.
piping
system assembled by piping components for conveying, distributing, mixing, separating, discharging, metering or stopping fluid flow
Note: besides piping components, it also includes pipe-supporting elements, but does not include supporting structures, such as building frame, pipe support, pipe gallery and base (pipe pier or foundation), etc.
gaseous hydrogen piping and pipelines
pipeline for transmitting gaseous hydrogen and hydrogen mixture
Note: Gaseous hydrogen piping and pipelines mentioned in this document include: gaseous hydrogen industrial piping, gaseous hydrogen transmission pipelines and gaseous hydrogen utility pipelines
gaseous hydrogen industrial piping
piping om various processing installations, hydrogen supply stations and other facilities for transmitting hydrogen medium
Note: industrial hydrogen refers to hydrogen medium meeting the requirements of Table 1 in GB/T 3634.1-2006.
gaseous hydrogen transmission pipelines
gas pipeline for transmitting hydrogen or hydrogen-doped gas between the place of origin, storage and users
gaseous hydrogen utility pipelines
gas pipelines within the scope of cities or towns that transmit hydrogen or hydrogen-doped medium between hydrogen production stations and end-users or between hydrogen production stations themselves, intended for public utilities or residential use, along with auxiliary facilities including line valve chambers and pressure regulation installations
hydrogen compatibility
ability of materials to work stably in hydrogen environment for a long time without performance degradation or failure
hydrogen compatibility test
test on material properties in a hydrogen environment at a certain pressure to evaluate whether they meet the design requirements
Note: There are various kind of hydrogen compatibility test, including slow strain rate tensile test and fracture toughness test in hydrogen environment.
hydrogen embrittlement
brittle rupture of metal materials due to penetration of hydrogen atoms, as a result of a significant decline in metal shaping and toughness
material performance factor
parameter used to describe the material performance loss (hydrogen embrittlement) of metal materials under hydrogen conditions
Note: The material performance factor is represented by the letter M in industrial pipelines, and by the letter H in gaseous hydrogen transmission pipelines and gaseous hydrogen utility pipelines.
hydrogen partial pressure
partial pressure of hydrogen in pipeline system at certain temperature
hydrogen embrittlement sensitivity coefficient
coefficient used to evaluate the reduction of cross-section shrinkage of smooth round bar samples in hydrogen environment compared with that in contrast environment through slow strain rate tensile test
threshold stress intensity factor for susceptibility to hydrogen-assisted cracking
KIH
critical value of stress intensity factor (KI) for initial crack initiation and extension of type I crack under the condition that plastic deformation of material is severely restricted to increase the force in hydrogen environment
Note 1: The threshold value used to characterize whether the material with crack defects will suffer hydrogen crack under the comprehensive action of stress and hydrogen environment.
Note 2: When the measured KIH meets the criteria for judging the effectiveness of plane strain, the value shall meet all thickness design requirements; this value is only applicable to the current test conditions when the criteria for judging the effectiveness of plane strain is not met. For judging the effectiveness of plane strain, see GB/T 21143 for reference.
resistant to rapid gas decompression; RGD
ability of non-metallic elastic materials to resist rapid gas (hydrogen) decompression without experiencing physical damage, such as blistering, cracking, etc.
severe cyclic conditions
one of the followings:
a) When the displacement stress range (SE) in pipes, piping components, or joints of a pipeline system [calculated according to Equation (14)] exceeds 0.8 times the allowable stress range (SA) [calculated according to Equation (15) or Equation (16)], while the equivalent number of cycles (N) [calculated according to Equation (18) ] exceeds 7000;
b) Other working conditions with the same effect [the displacement stress range SE is close to the allowable stress range SA, and the allowable stress range reduction factor f (calculated using Equation (17) or obtained by looking up Figure 4) is close to 1.0] determined by the designer based on experience.
combustible gas discharge system
generic term for facilities located outside the boundaries of a facility and its units, used for the discharge of combustible gas, including pipelines, knockout drums, water seal drums, flares or vent stacks
regenerative thermal oxidizer; RTO
device that purifies industrial organic waste gas by combustion and applies heat transfer media for heat exchange and heat up of the waste gas to be treated as well as heat exchange and cooling down of the purified exhaust gas
Note: A regenerative combustion system typically consists of switching devices, regenerative chamber, and a control system.
liquid hydrogen
hydrogen in liquid form
Note: Liquid hydrogen is a colorless and transparent cryogenic liquid with a normal boiling point of 20.38 K and a density of 70.77 kg/m3 at its boiling point.
cryogenic hydrogen
cold hydrogen gas formed by the evaporation of liquid hydrogen, with a pressure not lower than standard atmospheric pressure and a temperature of -196 °C ~ -253 °C
vacuum jacket insulated pipe
pipe that reduces heat loss by applying a vacuum insulation layer
Note: It typically consists of an inner pipe and an outer pipe, between which a vacuum layer is formed. It achieves insulation by wrapping the inner pipe with multilayer insulation material and evacuating the interlayer to create a vacuum.
stability austenitic steel
stainless steel with a stabilized austenitic microstructure that avoids martensite formation after cold working
Note: Based on the stability of austenite, austenitic stainless steels are classified into stable and metastable types. The more austenite-forming elements, such as nickel (Ni), nitrogen (N), carbon (C), and manganese (Mn) in austenitic stainless steel, the more stable the austenite phase will be.
4 Basic requirements
4.1 General
4.1.1 The materials, design and calculation, fabrication and installation, inspection and testing of gaseous hydrogen industrial piping shall comply with the provisions of this document and GB/T 20801.1-2025. In the event of any discrepancy between GB/T 20801.1-2025 and this document, the provisions of this document shall prevail.
4.1.2 The materials, design and calculation, construction and installation, inspection and testing, safety protection, commissioning and operation, usage and maintenance, as well as repair and emergency response for gaseous hydrogen transmission pipelines shall comply with the provisions of this document and the relevant regulations for gas transmission pipelines specified in GB/T 34275-2024. In case of any discrepancy between GB/T 34275-2024 and this document, the provisions of this document shall prevail.
4.1.3 The materials, design and calculation, construction and installation, inspection and testing, safety protection, commissioning and operation, usage and maintenance, as well as repair and emergency response for gaseous hydrogen utility pipelines shall comply with the provisions of this document and the relevant regulations for gas pipelines specified in GB/T 38942-2020. In case of any discrepancy between GB/T 38942-2020 and this document, the provisions of this document shall prevail.
4.1.4 Unless otherwise specified, the pressure in this document is gauge pressure.
4.2 Grading of gaseous hydrogen pressure piping
Gaseous hydrogen piping and pipelines within the scope of the Catalogue of Special Equipment shall be classified according to the following requirements:
a) Gaseous hydrogen industrial piping are classified into two grades: GC1 and GC2. Pipelines with a design pressure greater than or equal to 4.0 MPa are designated as GC1 grade, while all others are classified as GC2 grade.
b) Gaseous hydrogen transmission pipelines are classified into two grades: GA1 and GA2. Pipelines with a design pressure greater than or equal to 4.0 MPa are designated as GA1 grade, while all others are classified as GA2 grade.
c) Gaseous hydrogen utility pipelines are of GB1.
