Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 20801 consists of the following 6 parts under the general title of Pressure piping code - Industrial piping:
——Part 1: General;
——Part 2: Materials;
——Part 3: Design and calculation;
——Part 4: Fabrication and assembly;
——Part 5: Inspection and testing;
——Part 6: Safeguarding.
This is Part 3 of GB/T 20801.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 20801.3-2006 Pressure piping code - Industrial piping - Part 3: Design and calculation. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 20801.3-2006:
——The definition and application requirements of elevated temperature fluid service are added (see 3.2, 4.2.7.1, 5.2.2.7 and 6.7.2.4);
——The definition of severe cyclic conditions is modified (see 3.4; 3.4 of Edition 2006);
——The definition of creep strength enhanced ferritic steels is added (see 3.12);
——The sealing control requirements for valves of volatile organic compound system (see 5.1.11.8);
——The allowable stress criteria of ductile cast iron are modified (see Table 1; Table 1 of Edition 2006);
——The criteria for determining the maximum bolt installation load of flange joints are added (see 5.2.3.5);
——The definition of piping component is modified (see Table 13; Table 14 of Edition 2006);
——The applicable requirements of pipework component standards other than those listed in Table 13 are added (see 5.3.3);
——The evaluation criterion for the capability of tube flange bearing external load is added (see 6.4);
——The method and application scope of piping stress analysis are modified (see 7.2; 7.1.1 and 7.1.2 of Edition 2006);
——The stress strength condition of sustained load is modified (see 7.5.2; 7.3.1 of Edition 2006);
——The flexibility analysis method is modified (see 7.5.5.7; 7.3.3.6 of Edition 2006);
——The determination method of supporting reaction force is modified (see 7.5.5.8; 7.3.4 of Edition 2006);
——The corresponding requirements for supports and hangers of piping are modified (see clause 8; 7.4 of Edition 2006);
——The "Calculation of wind load and seismic load” is modified (see Annex A, Annex D of Edition 2006);
——The “piping layout” is added (see Annex B);
——The “international general standards of petrochemical valve” is modified (see Annex C; Annex A of Edition 2006);
——The “General requirements for stem seal of fugitive emission valves” is added (see Annex D);
——The "Flexibility coefficient and stress amplification coefficient” is modified (see Annex G; Annex C of Edition 2006);
——The "Allowable load of static equipment nozzle” is added (see Annex I);
——The “metal bellow expansion joint” is modified (see Annex J; Annex F of Edition 2006).
This part was proposed by and is under the jurisdiction of SAC/TC 262 National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China.
The previous edition of this part is as follows:
——GB/T 20801.3-2006.
Pressure piping code - Industrial piping -
Part 3: Design and calculation
1 Scope
This part of GB/T 20801 specifies the basic requirements for the design and calculation of pressure piping, including the design conditions, design criteria, piping components and their pressure design, and piping stress analysis.
This part is applicable to the design and calculation of pressure piping defined by GB/T 20801.1.
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 150 (all parts) Pressure vessel
GB/T 196 General purpose metric screw threads - Basic dimensions
GB/T 197 General purpose metric screw threads - Tolerances
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 3287 Malleable cast iron pipe fittings
GB/T 3420 Gray iron castings for pipe fittings
GB/T 3422 Cast-iron pressure pipe made by continuous casting process
GB/T 3733 24° cone connectors - Straight thread
GB/T 3734 24° cone connectors - Male
GB/T 3735 24° cone connectors - Straight thread long
GB/T 3736 24° cone connectors - Male long
GB/T 3737 24° cone connectors - Union
GB/T 3738 24° cone connectors - Straight thread elbow
GB/T 3739 24° cone connectors - Male elbow
GB/T 3740 24° cone connectors - Union elbow
GB/T 3741 24° cone connectors - Straight thread tee
GB/T 3742 24° cone connectors - Male tee
GB/T 3743 24° cone connectors - Straight thread run tee
GB/T 3744 24° cone connectors - Male run tee
GB/T 3745 24° cone connectors - Union tee
GB/T 3746 24° cone connectors - Union cross
GB/T 3747 24° cone connectors - Weld male
GB/T 3748 24° cone connectors - Bulkhead union
GB/T 3749 24° cone connectors - Bulkhead union elbow
GB/T 3750 24° cone connectors - Angle swivel screw connector
GB/T 3751 24° cone connectors - Connector for pressure gauge
GB/T 3752 24° cone connectors - Adjustable elbow
GB/T 3753 24° cone connectors - Adjustable tee
GB/T 3754 24° cone connectors - Swivel elbow with O-ring
GB/T 3755 24° cone connectors - Branch tee with O-ring
GB/T 3756 24° cone connectors - Swivel stud straight adapter with O-ring with stud end
GB/T 3757 24° cone connectors - Weld-in bulkhead straight connector
GB/T 3758 24° cone connectors - Weld-on nipple
GB/T 3759 24° cone connectors - Nut
GB/T 3760 24° cone connectors - Plug with O-ring
GB/T 3763 24° cone connectors and flared couplings - Hexagon thin nut
GB/T 3764 24° cone connectors - Ferrule
GB/T 3765 24° cone connectors - Specification
GB/T 5625 Flared couplings - Straight thread
GB/T 5626 Flared type tube fittings - Male connector - Assembly
GB/T 5627 Flared couplings - Male long
GB/T 5628 Flared couplings - Union
GB/T 5629 Flared couplings - Male elbow
GB/T 5630 Flared couplings - Union elbow
GB/T 5631 Flared couplings - Straight thread elbow
GB/T 5632 Flared couplings - Swivel elbow
GB/T 5633 Flared couplings - Straight thread branch tee
GB/T 5634 Flared couplings - Swivel run tee
GB/T 5635 Flared couplings - Male branch tee
GB/T 5637 Flared couplings - Straight thread run tee
GB/T 5638 Flared couplings - Swivel branch tee
GB/T 5639 Flared couplings - Union tee
GB/T 5641 Flared couplings - Union cross
GB/T 5642 Flared couplings - Weld male
GB/T 5643 Flared couplings - Bulkhead union
GB/T 5644 Flared couplings - Bulkhead union elbow
GB/T 5645 Flared couplings - Connector for pressure gauge
GB/T 5646 Flared couplings - Sleeve
GB/T 5647 Flared couplings - Style A nut
GB/T 5648 Flared couplings - Style B nut
GB/T 5649 Flared couplings - Lock nut and lockup washer
GB/T 5650 Flared couplings - Inverted flare bolts
GB/T 5651 Flared couplings - Seat insert
GB/T 5652 Flared couplings - Flared end
GB/T 5653 Flared couplings - Specification
GB/T 5782 Hexagon head bolts
GB/T 6170 Hexagon nuts, style 1
GB/T 6175 Hexagon nuts, style 2
GB/T 7306.1 Pipe threads with 55 degree thread angle where pressure-tight joints are made on the threads - Part 1: Parallel internal and taper external threads
GB/T 7306.2 Pipe threads with 55 degree thread angle where pressure-tight joints are made on the threads - Part 2: Taper internal and external threads
GB/T 8464 Cast iron and copper valves with screwed connections
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 and general use - Hose fittings - Part 2: Hose fittings with 24°cone connector ends
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 9711 Petroleum and natural gas industries - Steel pipe for pipeline transportation systems
GB/T 12220 Industrial valves - Marking
GB/T 12221 Metal calves - 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 12233 General purpose industrial valves - Casting iron globe valves and lift check 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 12240 Iron plug valves
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 12716 Pipe threads with the thread angle of 60 degrees where pressure-tight joints are made on threads
GB/T 12777 General specification for metal bellows expansion joints
GB/T 13295 Ductile iron pipes, fittings and accessories for water or gas applications
GB/T 13402 Large diameter steel pipe flanges
GB/T 13927 Industrial valves - Pressure testing
GB/T 13932 Cast iron swing check valves
GB/T 14383 Forged fittings socket-welding and threaded
GB/T 17116 (all parts) Pipe supports and hangers
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 17241 Cast iron pipe flanges
GB/T 17395 Dimensions, shapes, masses and tolerances of seamless steel tubes
GB/T 18615 Non-alloyed and stainless steel fittings for corrugated flexible metallic hoses
GB/T 19326 Forged branch outlet fittings,socket-welding,threaded and buttwelding
GB/T 20801.1-2020 Pressure piping code - Industrial piping - Part 1: General
GB/T 20801.2-2020 Pressure piping code - Industrial piping - Part 2: Materials
GB/T 20801.4-2020 Pressure piping code - Industrial piping - Part 4: Fabrication and assembly
GB/T 20801.5-2020 Pressure piping code - Industrial piping - Part 5: Inspection and testing
GB/T 20801.6-2020 Pressure piping code - Industrial piping - Part 6: Safeguarding
GB/T 26480 Valve inspection and testing
GB/T 26481 Valve test for fugitive emissions
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 - Induction 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 32294 Forged unions, socket-welding and threaded
GB/T 38343 Technical specification for flange joints installation
HG/T 3651 Unalloyed titanium and titanium alloy butt-welding seamless pipe fittings
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 (Class 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 2768 Components of valves - High pressure pipes, fittings and end-to-end dimensions of valves
JB/T 2769 Components of valves - high pressure threaded flanges
JB/T 2772 Components of valves - High pressure blanks
JB/T 2776 Components of valves - High pressure lens gaskets
JB/T 2778 Components of valves - Temperature marking of high pressure pipe and fasteners
JB 4732 Steel pressure vessels - Design by analysis
JB/T 6439 Methods of magnetic examination for valves
JB/T 6440 Methods of radiographic examination for steel castings valves
JB/T 6899 Valve fire resistance test
JB/T 6902-2008 Methods for liquid penetrant examination of valves
JB/T 6903-2008 Methods for ultrasonic examination of steel forgings for valves
JB/T 7747 Needle valve
JB/T 7927-2014 Valve cast steel visual quality requirements
JB/T 8527 Metallic sealing butterfly valve
JB/T 8937 Wafer type check valve
NB/T 47014 Welding procedure qualification for pressure equipment
SH/T 3419 Steel swaged nipples in petrochemical industry
SH/T 3425 Steel line blanks in petrochemical engineering
ISO 15848-1 Industrial valves - Measurement, test and qualification procedures for fugitive emissions - Part 1: Classification system and qualification procedures for type testing of valves
API 600 Steel gate - Valves flanged and butt-welding ends, bolted bonnets
ASME BPV Code VIII-2 ASME BPVC Section VIII - Rules for construction of pressure vessels division 2 alternative rules
ASME B16.9 Factory made wrought butt-welding fittings
ASME B16.11 Forged fittings, socket-welding and threaded
ASME B36.10M Welded and seamless wrought steel pipe
ASME B36.19M Stainless steel pipe
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 20801.1-2020, GB/T 20801.2-2020, GB/T 20801.4-2020, GB/T 20801.5-2020, GB/T 20801.6-2020 as well as the following apply.
3.1
piping system
piping determined by the same design conditions and connected with each other
3.2
elevated temperature fluid service
working condition in which the working temperature of the material is in the range where the high temperature strength reduction coefficient W of welded joints is less than 1 (see 4.2.7 and Table 5), which is equivalent to the working condition in which the working temperature is in the range in which the allowable stress is determined by the long-term strength of the material
3.3
fluid service
comprehensive term related to piping system application, which comprehensively considers fluid properties, operating conditions and other factors, and constitutes the basis of piping system design
3.4
severe cyclic conditions
working condition in which one of the following conditions occurs:
a) The displacement stress range SE [calculated using Equation (39)] in pipes, pipework components or joints in the piping system exceeds 0.8 times the allowable stress range SA [calculated using Equation (34) or Equation (35)], and the equivalent cycle number N [calculated by Equation (37)] exceeds 7,000;
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 (36) or obtained by looking up Figure 12) is close to 1.0] determined by the designer according to experience.
3.5
branch connection fitting
integral reinforcing fitting that connects the branch pipe to the main pipe through butt welding, socket welding and threaded connection
Note: Such as branch pipe socket and half coupling.
3.6
rating value
pressure value of piping components specified in the standard
3.7
schedule number
numerical code of pipe wall thickness series
3.8
displacement strain
in the pipe components, the strain caused by the displacement of piping constraint points and the additional displacement of end points as well as the strain caused by temperature changes
3.9
displacement stress
stress caused by displacement strain in piping components
3.10
structural attachments; attachment of support on piping
general name of the support and hanger parts directly connected with the piping or its insulation layer by welding, bolting or clamping
3.11
design minimum temperature
minimum temperature of components in expected working conditions, based on which the special design requirements and material evaluation requirements are determined
3.12
creep strength enhanced ferritic steels; CSEF
Cr-Mo ferritic steel with creep rupture strength improved through precipitation strengthening and grain refining
Note: It usually includes 91, 92, 911, 122 and 23 Cr-Mo ferritic steels.
3.13
volatile organic compounds; VOC
organic compound participating in photochemical reaction in atmosphere or any organic liquid that emits organic compounds into the atmosphere and meets one of the following conditions:
a) The true vapor pressure of volatile organic liquid is larger than 0.3 kPa at 20℃;
b) At 20℃, in the mixture of air and organic compounds, the total mass fraction of pure organic compounds with true vapor pressure greater than 0.3 kPa is equal to or higher than 20%, see GB 31570 and GB 31571.
4 Design conditions and design criteria
4.1 Design conditions
4.1.1 Design pressure
4.1.1.1 General requirements
4.1.1.1.1 The design pressure of each piping component in the piping system shall not be less than the pressure under the most severe condition with the combination of pressure and temperature that may be encountered during operation, except for the cases specified in 4.2.3.
4.1.1.1.2 The most severe working conditions lead to the maximum thickness and the highest pressure grade of piping components.
4.1.1.1.3 Under the most severe condition with the combination of pressure and temperature, possible operating conditions such as pressure source (such as pump and compressor), pressure pulsation, decomposition of unstable fluid, static head, failure or misoperation of control devices and valves, and environmental impact shall be considered.
4.1.1.2 Determination principles of design pressure
4.1.1.2.1 The design pressure of the piping equipped with safety relief device shall not be less than the set pressure (or the maximum marked bursting pressure) of the safety relief device, except for the cases specified in GB/T 20801.6-2020, 4.1.5 a) 2) and 4.1.5 c).
4.1.1.2.2 The design pressure of the piping without pressure relief device or which may be isolated or blocked from the pressure relief device shall not be less than the maximum pressure that may be generated as a result.
4.1.1.2.3 If the piping is directly connected to equipment and the whole is regarded as a pressure system, the design pressure of such piping shall not be less than that of the equipment.
4.1.1.2.4 The design pressure of centrifugal pump outlet piping shall not be less than the closing pressure of the pump.
4.1.1.2.5 For piping conveying refrigerant, liquefied hydrocarbons and other medium with low boiling point, the design pressure shall not be less than the maximum pressure that the medium possibly reaches when the valve is cut off or the medium is not flowing.
4.1.1.2.6 If the piping is divided into several separate pressure segments by separator (including jacket piping, blind plates, etc.), the design pressure of the separator shall not be less than the pressure under the most severe condition with the combination of pressure difference and temperature that the pressure chambers on both sides may encounter during operation.
4.1.1.2.7 For the vacuum piping equipped with safety control device, the design pressure shall be 1.25 times the maximum pressure difference or 0.1 MPa (whichever is the smaller), and it shall be designed according to the external pressure condition; for vacuum piping without safety control device, the design pressure is 0.1MPa.
4.1.2 Design temperature
4.1.2.1 General requirements
4.1.2.1.1 The design temperature of each piping component in the piping system shall be determined according to the temperature under the most severe condition with the combination of pressure and temperature that may be encountered during operation.
4.1.2.1.2 The design temperatures of different piping components in the same piping may be different.
4.1.2.1.3 When determining the design temperature, the influences of fluid temperature, ambient temperature, solar radiation, temperature of heating or cooling medium, and piping insulation and heat transfer shall be considered.
4.1.2.2 Determination principle of design temperature
4.1.2.2.1 For piping without external insulation layer, when the medium temperature is lower than 65℃, the design temperature of piping components is the same as the medium temperature, but solar radiation or other factors that may cause the medium temperature to rise shall be considered; when the medium temperature is higher than or equal to 65℃, the determination of design temperature of piping components shall meet the following requirements:
a) For valves, pipes, flanged ends and welded pipe fittings, 95% of the medium temperature shall be taken;
b) For flanges other than lap joint flanges, 90% of the medium temperature shall be taken;
c) For lap joint flanges, 85% of the medium temperature shall be taken;
d) For bolts, 80% of the medium temperature shall be taken;
e) The average wall temperature measured or that calculated according to heat transfer may also be taken.
4.1.2.2.2 Generally, the design temperature of external insulated piping shall be the medium temperature, but may also be the average wall temperature measured or that calculated according to heat transfer. The influence of heating or cooling on the design temperature shall be considered for piping with tracing piping or jacket structure.
4.1.2.2.3 The design temperature of the piping components of the internal insulation piping shall be determined by heat transfer calculation or test.
4.1.2.3 Design minimum temperature
The influence of design minimum temperature on piping design, material selection and stress analysis in 7.5.5 shall be considered in piping design.
4.1.3 Load conditions
4.1.3.1 Sustained loads
Sustained loads refer to the load acting on the piping, including:
a) Medium pressure: internal pressure, external pressure or maximum pressure difference of piping (design pressure and corresponding design temperature shall be taken as load conditions).
b) Gravity load: The gravity load to be taken into account in piping design includes:
1) Static load: the weight of piping components and thermal barrier materials as well as other permanent loads applied on and supported by the piping;
2) Live load: the weight of conveyed medium or hydraulic test medium and the weight of ice and snow caused by environmental and operating conditions.
4.1.3.2 Accidental loads
Accidental loads refer to the load acting on the piping in a short time, including:
a) Wind load: when designing outdoor piping, the wind load shall be calculated, and the calculation method is given in Annex A;
b) Seismic load: when designing piping, the horizontal force caused by earthquake shall be calculated, and the calculation method is given in Annex A;
c) Fluid discharge reaction force: the reaction force caused by the deceleration or discharge of fluid; and the design, layout and support of the piping shall be able to withstand this reaction force.
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Design conditions and design criteria
5 Piping components
6 Pressure design of piping components
7 Analysis of piping stress
8 Supports and hangers of piping
Annex A (Informative) Calculation of wind load and seismic load
Annex B (Informative) Piping layout
Annex C (Informative) Comparison of commonly-used industrial valve standards with foreign general petrochemical valve standards
Annex D (Informative) General requirements for stem seals of fugitive emission valves
Annex E (Informative) Practical calculation examples
Annex F (Informative) Computation of reinforcement by pressure-area method
Annex G (Normative) Flexibility coefficient and stress amplification coefficient
Annex H (Informative) Dynamic load analysis during opening and closing of valve in piping system
Annex I (Informative) Allowable load of static equipment nozzle
Annex J (Normative) Metal bellow expansion joint
Bibliography
Codeofchina.com is in charge of this English translation. In case of any doubt about the English translation, the Chinese original shall be considered authoritative.
GB/T 20801 consists of the following 6 parts under the general title of Pressure piping code - Industrial piping:
——Part 1: General;
——Part 2: Materials;
——Part 3: Design and calculation;
——Part 4: Fabrication and assembly;
——Part 5: Inspection and testing;
——Part 6: Safeguarding.
This is Part 3 of GB/T 20801.
This part is developed in accordance with the rules given in GB/T 1.1-2009.
This part replaces GB/T 20801.3-2006 Pressure piping code - Industrial piping - Part 3: Design and calculation. In addition to editorial changes, the following main technical changes have been made with respect to GB/T 20801.3-2006:
——The definition and application requirements of elevated temperature fluid service are added (see 3.2, 4.2.7.1, 5.2.2.7 and 6.7.2.4);
——The definition of severe cyclic conditions is modified (see 3.4; 3.4 of Edition 2006);
——The definition of creep strength enhanced ferritic steels is added (see 3.12);
——The sealing control requirements for valves of volatile organic compound system (see 5.1.11.8);
——The allowable stress criteria of ductile cast iron are modified (see Table 1; Table 1 of Edition 2006);
——The criteria for determining the maximum bolt installation load of flange joints are added (see 5.2.3.5);
——The definition of piping component is modified (see Table 13; Table 14 of Edition 2006);
——The applicable requirements of pipework component standards other than those listed in Table 13 are added (see 5.3.3);
——The evaluation criterion for the capability of tube flange bearing external load is added (see 6.4);
——The method and application scope of piping stress analysis are modified (see 7.2; 7.1.1 and 7.1.2 of Edition 2006);
——The stress strength condition of sustained load is modified (see 7.5.2; 7.3.1 of Edition 2006);
——The flexibility analysis method is modified (see 7.5.5.7; 7.3.3.6 of Edition 2006);
——The determination method of supporting reaction force is modified (see 7.5.5.8; 7.3.4 of Edition 2006);
——The corresponding requirements for supports and hangers of piping are modified (see clause 8; 7.4 of Edition 2006);
——The "Calculation of wind load and seismic load” is modified (see Annex A, Annex D of Edition 2006);
——The “piping layout” is added (see Annex B);
——The “international general standards of petrochemical valve” is modified (see Annex C; Annex A of Edition 2006);
——The “General requirements for stem seal of fugitive emission valves” is added (see Annex D);
——The "Flexibility coefficient and stress amplification coefficient” is modified (see Annex G; Annex C of Edition 2006);
——The "Allowable load of static equipment nozzle” is added (see Annex I);
——The “metal bellow expansion joint” is modified (see Annex J; Annex F of Edition 2006).
This part was proposed by and is under the jurisdiction of SAC/TC 262 National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China.
The previous edition of this part is as follows:
——GB/T 20801.3-2006.
Pressure piping code - Industrial piping -
Part 3: Design and calculation
1 Scope
This part of GB/T 20801 specifies the basic requirements for the design and calculation of pressure piping, including the design conditions, design criteria, piping components and their pressure design, and piping stress analysis.
This part is applicable to the design and calculation of pressure piping defined by GB/T 20801.1.
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 150 (all parts) Pressure vessel
GB/T 196 General purpose metric screw threads - Basic dimensions
GB/T 197 General purpose metric screw threads - Tolerances
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 3287 Malleable cast iron pipe fittings
GB/T 3420 Gray iron castings for pipe fittings
GB/T 3422 Cast-iron pressure pipe made by continuous casting process
GB/T 3733 24° cone connectors - Straight thread
GB/T 3734 24° cone connectors - Male
GB/T 3735 24° cone connectors - Straight thread long
GB/T 3736 24° cone connectors - Male long
GB/T 3737 24° cone connectors - Union
GB/T 3738 24° cone connectors - Straight thread elbow
GB/T 3739 24° cone connectors - Male elbow
GB/T 3740 24° cone connectors - Union elbow
GB/T 3741 24° cone connectors - Straight thread tee
GB/T 3742 24° cone connectors - Male tee
GB/T 3743 24° cone connectors - Straight thread run tee
GB/T 3744 24° cone connectors - Male run tee
GB/T 3745 24° cone connectors - Union tee
GB/T 3746 24° cone connectors - Union cross
GB/T 3747 24° cone connectors - Weld male
GB/T 3748 24° cone connectors - Bulkhead union
GB/T 3749 24° cone connectors - Bulkhead union elbow
GB/T 3750 24° cone connectors - Angle swivel screw connector
GB/T 3751 24° cone connectors - Connector for pressure gauge
GB/T 3752 24° cone connectors - Adjustable elbow
GB/T 3753 24° cone connectors - Adjustable tee
GB/T 3754 24° cone connectors - Swivel elbow with O-ring
GB/T 3755 24° cone connectors - Branch tee with O-ring
GB/T 3756 24° cone connectors - Swivel stud straight adapter with O-ring with stud end
GB/T 3757 24° cone connectors - Weld-in bulkhead straight connector
GB/T 3758 24° cone connectors - Weld-on nipple
GB/T 3759 24° cone connectors - Nut
GB/T 3760 24° cone connectors - Plug with O-ring
GB/T 3763 24° cone connectors and flared couplings - Hexagon thin nut
GB/T 3764 24° cone connectors - Ferrule
GB/T 3765 24° cone connectors - Specification
GB/T 5625 Flared couplings - Straight thread
GB/T 5626 Flared type tube fittings - Male connector - Assembly
GB/T 5627 Flared couplings - Male long
GB/T 5628 Flared couplings - Union
GB/T 5629 Flared couplings - Male elbow
GB/T 5630 Flared couplings - Union elbow
GB/T 5631 Flared couplings - Straight thread elbow
GB/T 5632 Flared couplings - Swivel elbow
GB/T 5633 Flared couplings - Straight thread branch tee
GB/T 5634 Flared couplings - Swivel run tee
GB/T 5635 Flared couplings - Male branch tee
GB/T 5637 Flared couplings - Straight thread run tee
GB/T 5638 Flared couplings - Swivel branch tee
GB/T 5639 Flared couplings - Union tee
GB/T 5641 Flared couplings - Union cross
GB/T 5642 Flared couplings - Weld male
GB/T 5643 Flared couplings - Bulkhead union
GB/T 5644 Flared couplings - Bulkhead union elbow
GB/T 5645 Flared couplings - Connector for pressure gauge
GB/T 5646 Flared couplings - Sleeve
GB/T 5647 Flared couplings - Style A nut
GB/T 5648 Flared couplings - Style B nut
GB/T 5649 Flared couplings - Lock nut and lockup washer
GB/T 5650 Flared couplings - Inverted flare bolts
GB/T 5651 Flared couplings - Seat insert
GB/T 5652 Flared couplings - Flared end
GB/T 5653 Flared couplings - Specification
GB/T 5782 Hexagon head bolts
GB/T 6170 Hexagon nuts, style 1
GB/T 6175 Hexagon nuts, style 2
GB/T 7306.1 Pipe threads with 55 degree thread angle where pressure-tight joints are made on the threads - Part 1: Parallel internal and taper external threads
GB/T 7306.2 Pipe threads with 55 degree thread angle where pressure-tight joints are made on the threads - Part 2: Taper internal and external threads
GB/T 8464 Cast iron and copper valves with screwed connections
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 and general use - Hose fittings - Part 2: Hose fittings with 24°cone connector ends
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 9711 Petroleum and natural gas industries - Steel pipe for pipeline transportation systems
GB/T 12220 Industrial valves - Marking
GB/T 12221 Metal calves - 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 12233 General purpose industrial valves - Casting iron globe valves and lift check 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 12240 Iron plug valves
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 12716 Pipe threads with the thread angle of 60 degrees where pressure-tight joints are made on threads
GB/T 12777 General specification for metal bellows expansion joints
GB/T 13295 Ductile iron pipes, fittings and accessories for water or gas applications
GB/T 13402 Large diameter steel pipe flanges
GB/T 13927 Industrial valves - Pressure testing
GB/T 13932 Cast iron swing check valves
GB/T 14383 Forged fittings socket-welding and threaded
GB/T 17116 (all parts) Pipe supports and hangers
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 17241 Cast iron pipe flanges
GB/T 17395 Dimensions, shapes, masses and tolerances of seamless steel tubes
GB/T 18615 Non-alloyed and stainless steel fittings for corrugated flexible metallic hoses
GB/T 19326 Forged branch outlet fittings,socket-welding,threaded and buttwelding
GB/T 20801.1-2020 Pressure piping code - Industrial piping - Part 1: General
GB/T 20801.2-2020 Pressure piping code - Industrial piping - Part 2: Materials
GB/T 20801.4-2020 Pressure piping code - Industrial piping - Part 4: Fabrication and assembly
GB/T 20801.5-2020 Pressure piping code - Industrial piping - Part 5: Inspection and testing
GB/T 20801.6-2020 Pressure piping code - Industrial piping - Part 6: Safeguarding
GB/T 26480 Valve inspection and testing
GB/T 26481 Valve test for fugitive emissions
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 - Induction 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 32294 Forged unions, socket-welding and threaded
GB/T 38343 Technical specification for flange joints installation
HG/T 3651 Unalloyed titanium and titanium alloy butt-welding seamless pipe fittings
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 (Class 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 2768 Components of valves - High pressure pipes, fittings and end-to-end dimensions of valves
JB/T 2769 Components of valves - high pressure threaded flanges
JB/T 2772 Components of valves - High pressure blanks
JB/T 2776 Components of valves - High pressure lens gaskets
JB/T 2778 Components of valves - Temperature marking of high pressure pipe and fasteners
JB 4732 Steel pressure vessels - Design by analysis
JB/T 6439 Methods of magnetic examination for valves
JB/T 6440 Methods of radiographic examination for steel castings valves
JB/T 6899 Valve fire resistance test
JB/T 6902-2008 Methods for liquid penetrant examination of valves
JB/T 6903-2008 Methods for ultrasonic examination of steel forgings for valves
JB/T 7747 Needle valve
JB/T 7927-2014 Valve cast steel visual quality requirements
JB/T 8527 Metallic sealing butterfly valve
JB/T 8937 Wafer type check valve
NB/T 47014 Welding procedure qualification for pressure equipment
SH/T 3419 Steel swaged nipples in petrochemical industry
SH/T 3425 Steel line blanks in petrochemical engineering
ISO 15848-1 Industrial valves - Measurement, test and qualification procedures for fugitive emissions - Part 1: Classification system and qualification procedures for type testing of valves
API 600 Steel gate - Valves flanged and butt-welding ends, bolted bonnets
ASME BPV Code VIII-2 ASME BPVC Section VIII - Rules for construction of pressure vessels division 2 alternative rules
ASME B16.9 Factory made wrought butt-welding fittings
ASME B16.11 Forged fittings, socket-welding and threaded
ASME B36.10M Welded and seamless wrought steel pipe
ASME B36.19M Stainless steel pipe
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 20801.1-2020, GB/T 20801.2-2020, GB/T 20801.4-2020, GB/T 20801.5-2020, GB/T 20801.6-2020 as well as the following apply.
3.1
piping system
piping determined by the same design conditions and connected with each other
3.2
elevated temperature fluid service
working condition in which the working temperature of the material is in the range where the high temperature strength reduction coefficient W of welded joints is less than 1 (see 4.2.7 and Table 5), which is equivalent to the working condition in which the working temperature is in the range in which the allowable stress is determined by the long-term strength of the material
3.3
fluid service
comprehensive term related to piping system application, which comprehensively considers fluid properties, operating conditions and other factors, and constitutes the basis of piping system design
3.4
severe cyclic conditions
working condition in which one of the following conditions occurs:
a) The displacement stress range SE [calculated using Equation (39)] in pipes, pipework components or joints in the piping system exceeds 0.8 times the allowable stress range SA [calculated using Equation (34) or Equation (35)], and the equivalent cycle number N [calculated by Equation (37)] exceeds 7,000;
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 (36) or obtained by looking up Figure 12) is close to 1.0] determined by the designer according to experience.
3.5
branch connection fitting
integral reinforcing fitting that connects the branch pipe to the main pipe through butt welding, socket welding and threaded connection
Note: Such as branch pipe socket and half coupling.
3.6
rating value
pressure value of piping components specified in the standard
3.7
schedule number
numerical code of pipe wall thickness series
3.8
displacement strain
in the pipe components, the strain caused by the displacement of piping constraint points and the additional displacement of end points as well as the strain caused by temperature changes
3.9
displacement stress
stress caused by displacement strain in piping components
3.10
structural attachments; attachment of support on piping
general name of the support and hanger parts directly connected with the piping or its insulation layer by welding, bolting or clamping
3.11
design minimum temperature
minimum temperature of components in expected working conditions, based on which the special design requirements and material evaluation requirements are determined
3.12
creep strength enhanced ferritic steels; CSEF
Cr-Mo ferritic steel with creep rupture strength improved through precipitation strengthening and grain refining
Note: It usually includes 91, 92, 911, 122 and 23 Cr-Mo ferritic steels.
3.13
volatile organic compounds; VOC
organic compound participating in photochemical reaction in atmosphere or any organic liquid that emits organic compounds into the atmosphere and meets one of the following conditions:
a) The true vapor pressure of volatile organic liquid is larger than 0.3 kPa at 20℃;
b) At 20℃, in the mixture of air and organic compounds, the total mass fraction of pure organic compounds with true vapor pressure greater than 0.3 kPa is equal to or higher than 20%, see GB 31570 and GB 31571.
4 Design conditions and design criteria
4.1 Design conditions
4.1.1 Design pressure
4.1.1.1 General requirements
4.1.1.1.1 The design pressure of each piping component in the piping system shall not be less than the pressure under the most severe condition with the combination of pressure and temperature that may be encountered during operation, except for the cases specified in 4.2.3.
4.1.1.1.2 The most severe working conditions lead to the maximum thickness and the highest pressure grade of piping components.
4.1.1.1.3 Under the most severe condition with the combination of pressure and temperature, possible operating conditions such as pressure source (such as pump and compressor), pressure pulsation, decomposition of unstable fluid, static head, failure or misoperation of control devices and valves, and environmental impact shall be considered.
4.1.1.2 Determination principles of design pressure
4.1.1.2.1 The design pressure of the piping equipped with safety relief device shall not be less than the set pressure (or the maximum marked bursting pressure) of the safety relief device, except for the cases specified in GB/T 20801.6-2020, 4.1.5 a) 2) and 4.1.5 c).
4.1.1.2.2 The design pressure of the piping without pressure relief device or which may be isolated or blocked from the pressure relief device shall not be less than the maximum pressure that may be generated as a result.
4.1.1.2.3 If the piping is directly connected to equipment and the whole is regarded as a pressure system, the design pressure of such piping shall not be less than that of the equipment.
4.1.1.2.4 The design pressure of centrifugal pump outlet piping shall not be less than the closing pressure of the pump.
4.1.1.2.5 For piping conveying refrigerant, liquefied hydrocarbons and other medium with low boiling point, the design pressure shall not be less than the maximum pressure that the medium possibly reaches when the valve is cut off or the medium is not flowing.
4.1.1.2.6 If the piping is divided into several separate pressure segments by separator (including jacket piping, blind plates, etc.), the design pressure of the separator shall not be less than the pressure under the most severe condition with the combination of pressure difference and temperature that the pressure chambers on both sides may encounter during operation.
4.1.1.2.7 For the vacuum piping equipped with safety control device, the design pressure shall be 1.25 times the maximum pressure difference or 0.1 MPa (whichever is the smaller), and it shall be designed according to the external pressure condition; for vacuum piping without safety control device, the design pressure is 0.1MPa.
4.1.2 Design temperature
4.1.2.1 General requirements
4.1.2.1.1 The design temperature of each piping component in the piping system shall be determined according to the temperature under the most severe condition with the combination of pressure and temperature that may be encountered during operation.
4.1.2.1.2 The design temperatures of different piping components in the same piping may be different.
4.1.2.1.3 When determining the design temperature, the influences of fluid temperature, ambient temperature, solar radiation, temperature of heating or cooling medium, and piping insulation and heat transfer shall be considered.
4.1.2.2 Determination principle of design temperature
4.1.2.2.1 For piping without external insulation layer, when the medium temperature is lower than 65℃, the design temperature of piping components is the same as the medium temperature, but solar radiation or other factors that may cause the medium temperature to rise shall be considered; when the medium temperature is higher than or equal to 65℃, the determination of design temperature of piping components shall meet the following requirements:
a) For valves, pipes, flanged ends and welded pipe fittings, 95% of the medium temperature shall be taken;
b) For flanges other than lap joint flanges, 90% of the medium temperature shall be taken;
c) For lap joint flanges, 85% of the medium temperature shall be taken;
d) For bolts, 80% of the medium temperature shall be taken;
e) The average wall temperature measured or that calculated according to heat transfer may also be taken.
4.1.2.2.2 Generally, the design temperature of external insulated piping shall be the medium temperature, but may also be the average wall temperature measured or that calculated according to heat transfer. The influence of heating or cooling on the design temperature shall be considered for piping with tracing piping or jacket structure.
4.1.2.2.3 The design temperature of the piping components of the internal insulation piping shall be determined by heat transfer calculation or test.
4.1.2.3 Design minimum temperature
The influence of design minimum temperature on piping design, material selection and stress analysis in 7.5.5 shall be considered in piping design.
4.1.3 Load conditions
4.1.3.1 Sustained loads
Sustained loads refer to the load acting on the piping, including:
a) Medium pressure: internal pressure, external pressure or maximum pressure difference of piping (design pressure and corresponding design temperature shall be taken as load conditions).
b) Gravity load: The gravity load to be taken into account in piping design includes:
1) Static load: the weight of piping components and thermal barrier materials as well as other permanent loads applied on and supported by the piping;
2) Live load: the weight of conveyed medium or hydraulic test medium and the weight of ice and snow caused by environmental and operating conditions.
4.1.3.2 Accidental loads
Accidental loads refer to the load acting on the piping in a short time, including:
a) Wind load: when designing outdoor piping, the wind load shall be calculated, and the calculation method is given in Annex A;
b) Seismic load: when designing piping, the horizontal force caused by earthquake shall be calculated, and the calculation method is given in Annex A;
c) Fluid discharge reaction force: the reaction force caused by the deceleration or discharge of fluid; and the design, layout and support of the piping shall be able to withstand this reaction force.
Contents of GB/T 20801.3-2020
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Design conditions and design criteria
5 Piping components
6 Pressure design of piping components
7 Analysis of piping stress
8 Supports and hangers of piping
Annex A (Informative) Calculation of wind load and seismic load
Annex B (Informative) Piping layout
Annex C (Informative) Comparison of commonly-used industrial valve standards with foreign general petrochemical valve standards
Annex D (Informative) General requirements for stem seals of fugitive emission valves
Annex E (Informative) Practical calculation examples
Annex F (Informative) Computation of reinforcement by pressure-area method
Annex G (Normative) Flexibility coefficient and stress amplification coefficient
Annex H (Informative) Dynamic load analysis during opening and closing of valve in piping system
Annex I (Informative) Allowable load of static equipment nozzle
Annex J (Normative) Metal bellow expansion joint
Bibliography
