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.
This standard is corresponding to ISO 15649: 2001 "Petroleum and Natural Gas Industries-Piping" and it is not equivalent to ISO 15649: 2001.
GB/T 20801 "Pressure Piping Code-Industrial Piping" consists of the following six parts:
——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 part is Part 3 of GB/T 20801.
In this Part, Appendixes C and F are normative, and Appendixes A, B, D, E and G are informative.
This Part was proposed by Sub-committee of Pressure Pipeline of National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262/SC 3).
This Part is under the jurisdiction of National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).
Drafting organizations of this Part: National Technology Center of Process Equipment, SINOPEC Shanghai Engineering Co., Ltd., East China University of Science and Technology, Bureau of Safety Supervision of Special Equipment (SESA) of AQSIQ, Economics & Development Research Institute (EDRI) of SINOPEC, Engineering and Construction Administration Department of SINOPEC and Liaoning Provincial Institute of Safety Science.
Chief drafting staffs of this Part: Qin Shujing, Cai Nuanshu, Ding Bomin, Ying Daoyan, Xia Dejie, Gao Jixuan, Xiu Changzheng, Wang Zhen'an, Ye Wenbang, Shou Bi'nan, Wang Weiguo, Huang Zhenglin, Zhou Jiaxiang, Tang Yongjin, Zhang Baojiang, Yu Puyi and Liu Jinshan.
Pressure Piping Code—Industrial Piping—
Part 3: Design and Calculation
压力管道规范 工业管道
第3部分：设计和计算
1 Scope
This Part specifies the basic requirements for the design and calculation of pressure piping within the scope of GB/T 30801.1, including the requirements for such aspects as design conditions, design criteria, piping components and their pressure design as well as the piping stress analysis.
2 Normative References
The following normative documents contain provisions which, through reference in this Part of GB/T 20801, constitute provisions of this Part. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties whose enter into agreement according to this Part are encouraged to research whether the latest editions of these references are applied or not. For undated references, the latest editions of the normative documents are applicable to this Part.
GB 150 "Steel Pressure Vessels"
GB/T 196-2003 "General Purpose Metric Screw Threads-Basic Dimensions" (ISO 724: 1993, MOD)
GB/T 197-2003 "General Purpose Metric Screw Threads-Tolerances" (ISO 965-1: 1998, MOD)
GB/T 539-1995 "Oil-resisting Asbestos-rubber Sheets"
GB/T 1031-1995 "Surface Roughness Parameters and Their Values" (neq ISO 468: 1982)
GB/T 1047-2005 "Pipework Components--Definition and Selection of DN (Nominal Size)" (ISO 6708: 1995, MOD)
GB/T 1048-2005 "Pipework Components--Definition and Selection of PN" (ISO/CD 7268 : 1996, MOD)
GB/T 1220-1992 "Stainless Steel Bars"
GB/T 3077-1999 "Alloy Structure Steels"
GB/T 3098.1-2000 "Mechanical Properties of Fasteners-Bolts, Screws and Studs" (idt ISO 898-1: 1999)
GB/T 3098.6-2000 "Mechanical Properties of Corrosion-resistant Stainless-steel Fasteners-Part 1: Bolts, Screws and Studs" (idt ISO 3506-1: 1997)
GB/T 3287-2000 "Malleable Cast Iron Pipe Fittings" (eqv ISO 49: 1994)
GB/T 3420-1982 "Gray Iron Castings for Pipe Fittings"
GB/T 3422-1982 "Cast-iron Pressure Pipe Made by Continuous Casting Process"
GB/T 3985-1995 "Asbestos-rubber Sheets"
GB/T 5782-2000 "Hexagon Head Bolts" (eqv ISO 4014: 1999)
GB/T 6170-2000 "Hexagon Nuts, Style 1" (eqv ISO 4032: 1999)
GB/T 6175-2000 "Hexagon Nuts, Style 2" (eqv ISO 4033: 1999)
GB/T 7233-1987 "Methods for Ultrasonic Testing and for Specifying Quality Levels of Steel Castings"
GB/T 7306.1- 2000 "Pipe Threads with 55 Degree Thread Angle Where Pressure-tight Joints are Made on the Threads--Part 1: Parallel Internal and Taper External Threads" (eqv ISO 7-1: 1994)
GB/T 7306.2-2000 "Pipe Threads with 55 Degree Thread Angle Where Pressure-tight Joints are Made on the Threads--Part 2: Taper Internal and External Threads" (eqv ISO 7-1: 1994)
GB/T 9065-1988 "Connection Dimension of Hydraulic Hose Joints"
GB/T 9711.1-1997 "Petroleum and Natural Gas Industries-Steel Pipe for Pipelines-Technical Deivery Conditions-Part 1: Pipes of Requirement Class A" (eqv ISO 3183-1: 1996)
GB/T 12220-1989 "General Purpose Industrial Valves-Marking" (idt ISO 5209: 1977)
GB/T 12221-2005 "Metal calves--Face to Face, End to End, Center to Face and Center to End Dimensions" (ISO 5758: 1982, MOD)
GB/T 12224-2005 "General Requirements for Industrial Steel Valves"
GB/T 12232-2005 "General Purpose Industrial Valve-Flanged Iron Gate Valves"
GB/T 12233-2006 "General Purpose Industrial Valves-Casting Iron Globe Valves and Lift Check Valves"
GB/T 12234-1989 "General Purpose Industrial Valves-Flanged and Butt-weld Steel Gate Valves"
GB/T 12235-1989 "General Purpose Industrial Valves-Flanged Steel Globe Valves and Lift Check Valves"
GB/T 12236-1989 "General Purpose Industrial Valves-Steel Swing Check Valve"
GB/T 12237-1989 "General Purpose Industrial Valves-Flanged and Butt-weld End Steel Ball Valves"
GB/T 12238-1989 "General Purpose Industrial Valve-Flanged and Wafer Butterfly Valves"
GB/T 12239-1989 "General Purpose Industrial Valves-Diaphragm Valves"
GB/T 12240-1989 "General Purpose Industrial Valves-Iron Plug Valve"
GB/T 12241-2005 "Safety Valves--General Requirements" (ISO 4126-1: 1991, MOD)
GB/T 12243-2005 "Spring Loaded Safety Valves"
GB/T 12246-2006 "Pilot-operated Reducing Valves"
GB/T 12459-2005 "Steel Butt-welding Seamless Pipe Fittings"
GB/T 12716-2002 "Pipe Threads with the Thread Angle of 60 Degrees Where Pressure-tight Joints are Made on the Threads"
GB/T 12777-1999 "General Specification for Metal Bellows Expansion Joints"
GB/T 13295-2003 "Ductile Iron Pipes, Fittings and Accessories for Water or Gas Applications" (ISO 2531: 1998, MOD)
GB/T 13401-2005 "Steel Plate Butt-welding Pipe Fittings"
GB/T 13402-1992 "Large-diameter Carbon Steel Pipe Flanges"
GB/T 13403-1992 "Gaskets for Large-diameter Carbon Steel Pipe Flanges"
GB/T 13927-1992 "Pressure Testing for General Purpose Valves" (neq ISO 5208: 1982)
GB/T 13932-1992 "General Purpose Industrial Valves-Cast Iron Swing Check Valves"
GB/T 14383-1993 "Forged Steel Socket Welding Pipe Fittings"
GB/T 14626-1993 "Forged Steel Threaded Pipe Fittings"
GB/T 15185-1994 "Cast Iron and Copper Alloy Ball Valves"
GB/T 17116.1-1997 "Pipe Supports and Hangers-Part 1: Technical Specification"
GB/T 17116.2-1997 "Pipe Supports and Hangers-Part 2: Pipe Attachments"
GB/T 17116.3-1997 "Pipe Supports and Hangers-Part 3: Middle Connection Attachments and Building Structure Attachments"
GB/T 17185-1997 "Steel Pipe Fittings for Flanged Joint"
GB/T 17241-1998 "Cast Iron Pipe Flanges" (neq ISO 7005: 1988)
GB/T 17395-1998 "Dimensions, Shapes, Masses and Tolerances of Seamless Steel Tubes" (neq ISO 1127: 1992)
GB/T 18615-2002 "Non-alloyed and Stainless Steel Fittings for Corrugated Flexible Metallic Hoses" (neq ISO 10806: 1994)
GB/T 19326-2003 "Forged Branch Outlet Fittings-Socket Welding, Threaded and Butt-welding Ends"
GB/T 20801.1-2006 "Pressure Piping Code-Industrial Piping-Part 1: General"
GB/T 20801.2-2006 "Pressure Piping Code-Industrial Piping-Part 2: Materials"
GB/T 20801.4-2006 "Pressure Piping Code-Industrial Piping- Part 4: Fabrication and Assembly"
GB/T 20801.5-2006 "Pressure Piping Code-Industrial Piping-Part 5: Inspection and Testing"
HG/T 3651-1999 "Unalloyed Titanium and Titanium Alloy Butt-welding Seamless Pipe Fittings"
HG 20553-1993 "Seamless and Welded Pipe Dimension Selection Serials for Chemical Industry Piping"
HG 20592~20604 "Steel Tube Flanges (European System)"
HG 20615~20625 "Steel Tube Flanges (American System)"
HG 20605 "Welded Steel Pipe Flange Joints and Groove Size (European System)"
HG 20606 "Nonmetallic Flat Gaskets for Steel Tube Flanges (European System)"
HG 20607 "Polytetrafluoroethylene Envelope Gaskets for Steel Tube Flanges (European System)"
HG 20608 "Flexible Graphite Compound Gaskets for Steel Tube Flanges (European System)"
HG 20609 "Metal Jacketed Gaskets for Steel Tube Flanges (European System)"
HG 20610 "Spiral Wound Gaskets for Steel Tube Flanges (European System)"
HG 20611 "Grooved Compound Gaskets for Use with Steel Pipe Flanges (European System)"
HG 20612 "Metal Ring Gaskets for Steel Tube Flanges (European System)"
HG 20613 "Fasteners Used for Steel Pipe Flanges (European System)"
HG 20626 "Welded Steel Pipe Flange Joints and Groove Size (American System)"
HG 20627 "Nonmetallic Flat Gaskets for Steel Tube Flanges (American System)"
HG 20628 "Polytetrafluoroethylene Envelope Gaskets for Steel Tube Flanges (American System)"
HG 20629 "Flexible Graphite Compound Gaskets for Steel Tube Flanges (American System)"
HG 20630 "Metal Jacketed Gaskets for Steel Tube Flanges (American System)"
HG 20631 "Spiral Wound Gaskets for Steel Tube Flanges (American System)"
HG 20632 "Grooved Compound Gaskets for Use with Steel Pipe Flanges (American System)"
HG 20633 "Metal Ring Gaskets for Steel Tube Flanges (American System)"
HG 20634 "Metal Ring Gaskets for Steel Tube Flanges (American System)"
HG 21547-1993 "Steel Blank, Spacer Ring and Figure 8 Blind Plate Used for Piping"
JB/T 2768~2778-1992 "PN16.0~32.0MPa Threaded Flanges, Pipes, Fasteners and Lens Gaskets"
JB 4708-2000 "Welding Procedure Qualification for Steel Pressure Vessels"
JB 4732-1995 "Steel Pressure Vessels-Design by Analysis"
JB/T 6439-1992 "Methods of Magnetic Particle Testing for Pressure Valve Steel Castings"
JB/T 6440-1992 "Methods of Radiographic Examination for Steel Castings Valves"
JB/T 6899-1993 "Valves Fire Test"
JB/T 6902-1993 "Methods for Liquid Penetrant Examination of Valve Steel Castings"
JB/T 7747-1995 "Needle Valve"
JB/T 7927-1999 "Valve Cast Steel Visual Quality Requirements"
JB/T 8527-1997 "Metal Seal Butterfly Valves"
JB/T 8937-1999 "Wafer Type Check Valve"
JB/T 9092-1999 "Valve Inspection and Testing"
3 Terms and Definitions
In addition to the terms and definitions stated in this Part, those established in other partsof GB/T 20801 are also applicable to this Part.
3.1
Piping system
The pipes determined under the same design conditions and interconnected.
3.2
Balanced piping system
The piping system with uniform strain distribution, no excessive strained points and the stress in direct proportion to the total displacement strain.
3.3
Fluid service
One of the design conditions of piping system, consisting of fluid property, operating conditions and other factors.
3.4
Severe cyclic conditions
The operating condition when any one of the following conditions occurs:
a) The displacement stress range SE [calculated according to Formula (37)] of the pipes, pipe components or joints in the piping system exceeds 0.8 times of the allowable stress range SA [calculated according to Formula (32) or Formula (33)], meanwhile, the equivalent cycle times N [calculated according to Formula (35)] exceeds 7,000;
b) The designers judge other operating conditions having the same effects according to their experiences.
3.5
Branch connection fitting
The integrally reinforced fittings by connecting the branch pipes onto the main pipe through butt welding connection, socket welding connection or threaded connection, such as branch pipe support and half coupling, etc.
3.6
Rating value
The pressure value of piping components as specified in standards.
3.7
Schedule number
The code number of the values of pipe wall thickness series.
3.8
Displacement strain
In the piping components, the strain produced by the displacement of piping confined points due to earthquake and wind force and the strain produced due to temperature variation is generally called as "displacement strain".
3.9
Displacement stress
The stress in piping components caused by displacement strain.
3.10
Cold spring
The predeformation applied onto the piping during the erection stage in order to compensate the possible reverse deformation of piping under the service conditions.
4 Design Conditions and Design Criteria
4.1 Design Conditions
4.1.1 Design Pressure
4.1.1.1 General requirements
The design pressure of each piping component in the piping system shall not be less than the pressure under the combination operating condition of the most rigorous pressure and temperature that may be met during the operation, however, the conditions specified in 4.2.3 are excluded. The combination operating condition of the most rigorous pressure and temperature shall take account of the possible operating conditions produced by the pressure source (such as pump and compressor), the pressure pulsation, the decomposition of unstable fluid, the failure or misoperation of static pressure head, control device and valves as well as the environmental impact.
4.1.1.2 Principle for determination of design pressure
a) As for the piping equipped with safety relief device, its design pressure shall not be less than the set pressure of the safety relief device (or the maximum marked burst pressure), however, the conditions specified in 4.1.6.1b), 4.1.6.2 and 4.1.6.3 of GB/T 20801.6-2006 are excluded;
b) Where the piping and equipments are directly connected into one single pressure system, the design pressure of the piping shall not be less than the design pressure of the equipments;
c) As for piping that is not equipped with pressure relief device or may be isolated and blocked from the pressure relief device, its design pressure shall not be less than the maximum pressure that may be produced accordingly;
d) The design pressure of the outlet piping of centrifugal pump shall not be less than the closing pressure of this pump;
e) As for the pipings used for conveying refrigerant or such low boiling point medium as liquefied hydrocarbons, the design pressure of the piping shall not be less than the maximum saturated vapor pressure that may be reached by the medium when the valves are shut off or the medium is not flowing.
f) Where the piping is divided into several separate compressed sections with separators (including jacket pipes and blanking plates), the design pressure of this separator shall not be less than the pressure under the combination operating condition of the most rigorous pressure difference and temperature that may be met by the compression chambers at both sides during the operation;
g) As for the vacuum pipe with safety control device, its design pressure shall be taken as the smaller value between 1.25 times of the maximum pressure difference and 0.1MPa, and it shall be designed according to the external pressure; as for the vacuum pipe without safety control device, the design pressure shall be taken as 0.1MPa.
4.1.2 Design Temperature
4.1.2.1 General Requirements
The design temperature of each piping component in the piping system shall be determined according to the temperature under the combination operating condition of the most rigorous pressure and temperature that may be met during the operation, and different piping components in one same piping may have different design temperature.
4.1.2.2 Principle for determination of design temperature
a) Where the medium temperature is less than 65℃, the design temperature of the piping components of the piping without thermal insulating layer is identical to the medium temperature, however, the sunshine radiation or other factors that may result in the rising of medium temperature also shall be considered; where the medium temperature larger than or equal to 65℃,the determination of the design temperature of piping components of the piping without thermal insulating layer shall meet the following requirements:
1) 95% of the medium temperature for valves, pipe, flared end and welded fittings;
2) 90% of the medium temperature for flanges, the lap joint flanges excluded;
3) 85% of the medium temperature for lap joint flanges;
4) 80% of the medium temperature for bolts;
5) The measured average wall temperature or the average wall temperature calculated according to heat transfer may also be taken.
b) The design temperature of the externally insulated piping generally is taken as the medium temperature, however, it may also be taken as the measured average wall temperature or the average wall temperature calculated according to the heat transfer, and the piping adopting with tracing pipes or jacket structures shall be considered with the influence of heating or cooling on the design temperature.
c) As for the components of the internally insulated piping, the design temperature shall be determined through calculation with heat transfer or through tests.
4.1.2.3 Minimum working temperature and maximum working temperature
For the piping design, the influence of minimum working temperature and maximum working temperature on the material selection and the flexibility analysis in 7.3.3 shall be taken into consideration.
4.1.3 Loading Condition
The following loads shall be considered in the piping design:
a) Internal pressure, external pressure or maximum pressure difference (the design pressure and the corresponding design temperature shall be taken as the loading conditions together).
b) Gravity loads:
1) Piping components, heat insulating materials as well as the other gravity loads supported by the piping;
2) Fluid weight (including the hydraulic test) as well as the ice and snow weight in cold areas.
c) Dynamic loads:
1) Wind load;
2) Seismic load;
3) Impact, pressure oscillation and flash vaporization caused by fluid flow;
4) Vibration caused by machine, wind or fluid flow;
5) Counter stress by the discharging of fluid.
d) Temperature difference loads:
1) Loads produced due to the piping restriction when the temperature changes;
2) The temperature stress produced due to the sharp change or misdistribution of temperature, for instance, the temperature stress that may be caused by the thick walled pipe or stratified flowing of fluid;
3) Loads produced due to the different expansion coefficients when the temperature changes, such as bimetal pipe, jacket pipe, nonmetallic lined pipe, etc.
e) Loads caused by the displacement of end points.
Loads caused when the pipe supports and hangers or the pipe connected equipments are displaced.
4.1.4 Additional Thickness
a) The piping design shall have adequate corrosion allowance, the corrosion allowance shall be determined according to the expected service life and the corrosion rate of medium to material, moreover, the factors, such as the erosion and local corrosion, also shall be taken into consideration.
b) To determine the minimum thickness of piping components, the allowance required for corrosion, erosion, and depth of thread or trench shall be included. The thickening of pipe wall shall be considered in order to preventing the supporting, freezing, back filling, transporting and handling from causing overload stress and deformation, by which such phenomena as damage, collapse or unstability may occur.
Foreword IV
1 Scope
2 Normative References
3 Terms and Definitions
4 Design Conditions and Design Criteria
4.1 Design Conditions
4.1.1 Design Pressure
4.1.2 Design Temperature
4.1.3 Loading Condition
4.1.4 Additional Thickness
4.1.5 Environmental Impact
4.1.6 Buried Piping
4.2 Design Criteria
4.2.1 Pressure-Temperature Design Criteria for Piping Components
4.2.2 Pressure-Temperature Design Criteria for Piping
4.2.3 Permissible Variation Range of Pressure and Temperature
4.2.4 Allowable Stress
4.2.5 Longitudinal Weld Joint Efficiency Φw
4.2.6 Quality Coefficient Φc of Casting
5 Piping Components
5.1 Selection of Piping Components
5.1.1 General Requirements
5.1.2 Pipes and Butt Welding Fittings
5.1.3 Bent Pipes
5.1.4 Miter Elbows
5.1.5 Short Radius Elbows
5.1.6 Lap Joint
5.1.7 Branch Connection and Its Fittings
5.1.8 Flanges
5.1.9 Gaskets
5.1.10 Fasteners
5.1.11 Valves
5.2 Selection of the Connection Type of Piping Components
5.2.1 General Requirements
5.2.2 Welded Joints
5.2.3 Flange Connection
5.2.4 Expanded Joints
5.2.5 Connection of Pipe Threads Where Pressure-tight Joints Are Made on the Threads
5.2.6 Straight Thread Connection
5.2.7 Connection of Fittings of Flaring and Non-flaring Stitching Type
5.2.8 Caulking Joint
5.2.9 Special Pipe Joint
5.3 Types and Dimensions of Piping Components
6 Pressure Design of Piping Components
6.1 Straight Pipe
6.2 Bent Pipes or Elbows
6.3 Miter Elbows
6.4 Pressure Design of Pipe Flange and Blind Flange
6.5 Blanking Plate
6.6 Other Piping Components
6.7 Equal-area Reinforcement Method for Branch Connection
6.7.1 Symbols
6.7.2 Application Scope of Equal-area Reinforcement Method
6.7.3 Conditions not Requiring Reinforcement
6.7.4 Reinforcement Calculation of Branch Pipe Directly Welded on Main Pipe
6.7.5 Reinforcement Calculation of Branch Pipe Connection with Extrusion Forming Joint
6.7.6 Reinforcement Design of Branch Pipe Connection on End Socket
6.8 Calculation of Integrally-shaped Tee Joint with Pressure Area Method
7 Piping Stress Analysis
7.1 General Requirements
7.2 Loads and Load Combination
7.2.1 Load and Its Classification
7.2.2 Working conditions of load combination
7.2.3 Temporary load conditions and requirements
7.3 Stress Analysis and Strength Condition
7.3.1 Stress Strength Conditions of Permanent Load
7.3.2 Stress Strength Conditions of Combination Working Conditions of Permanent Load and Temporary Load
7.3.3 Flexibility analysis
7.3.4 Determination of Support Counter Force
7.4 Pipe Supports and Hangers
7.4.1 General Requirements
7.4.2 Material Requirements
7.4.3 Design Requirements
7.4.4 Arrangement requirements
Appendix A (Informative) International Standards for Petroleum and Chemical Valves
Appendix B (Informative) Examples of Calculation
Appendix C (Normative) Flexibility Factor and Stress Enhancement Coefficient
Appendix D (Informative) Calculation of Wind Load and Seismic Load
D.1 Calculation of Horizontal Wind Power
D.2 Calculation of Horizontal Seismic Force and Seismic Bending Moment
Appendix E (Informative) Analysis on Dynamic Loads for the Opening and Closing of Valves in Piping System
E.1 Quick Closing of Valves
E.2 Opening of Relief Valves
Appendix F (Normative) Expansion Joint
F.1 Requirements for Piping Design
F.1.1 Design Conditions of Expansion Joint
F.1.2 Piping Design Requirements
F.2 Requirements for Expansion Joint Manufacturer
F.2.1 Design of Expansion Joint
F.2.2 Manufacture, Inspection and Pressure Test of Expansion Joint
Appendix G (Informative)Computation of Reinforcement with Pressure Area Method
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.
This standard is corresponding to ISO 15649: 2001 "Petroleum and Natural Gas Industries-Piping" and it is not equivalent to ISO 15649: 2001.
GB/T 20801 "Pressure Piping Code-Industrial Piping" consists of the following six parts:
——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 part is Part 3 of GB/T 20801.
In this Part, Appendixes C and F are normative, and Appendixes A, B, D, E and G are informative.
This Part was proposed by Sub-committee of Pressure Pipeline of National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262/SC 3).
This Part is under the jurisdiction of National Technical Committee on Boilers and Pressure Vessels of Standardization Administration of China (SAC/TC 262).
Drafting organizations of this Part: National Technology Center of Process Equipment, SINOPEC Shanghai Engineering Co., Ltd., East China University of Science and Technology, Bureau of Safety Supervision of Special Equipment (SESA) of AQSIQ, Economics & Development Research Institute (EDRI) of SINOPEC, Engineering and Construction Administration Department of SINOPEC and Liaoning Provincial Institute of Safety Science.
Chief drafting staffs of this Part: Qin Shujing, Cai Nuanshu, Ding Bomin, Ying Daoyan, Xia Dejie, Gao Jixuan, Xiu Changzheng, Wang Zhen'an, Ye Wenbang, Shou Bi'nan, Wang Weiguo, Huang Zhenglin, Zhou Jiaxiang, Tang Yongjin, Zhang Baojiang, Yu Puyi and Liu Jinshan.
Pressure Piping Code—Industrial Piping—
Part 3: Design and Calculation
压力管道规范 工业管道
第3部分：设计和计算
1 Scope
This Part specifies the basic requirements for the design and calculation of pressure piping within the scope of GB/T 30801.1, including the requirements for such aspects as design conditions, design criteria, piping components and their pressure design as well as the piping stress analysis.
2 Normative References
The following normative documents contain provisions which, through reference in this Part of GB/T 20801, constitute provisions of this Part. For dated reference, subsequent amendments to (excluding correction to), or revisions of, any of these publications do not apply. However, the parties whose enter into agreement according to this Part are encouraged to research whether the latest editions of these references are applied or not. For undated references, the latest editions of the normative documents are applicable to this Part.
GB 150 "Steel Pressure Vessels"
GB/T 196-2003 "General Purpose Metric Screw Threads-Basic Dimensions" (ISO 724: 1993, MOD)
GB/T 197-2003 "General Purpose Metric Screw Threads-Tolerances" (ISO 965-1: 1998, MOD)
GB/T 539-1995 "Oil-resisting Asbestos-rubber Sheets"
GB/T 1031-1995 "Surface Roughness Parameters and Their Values" (neq ISO 468: 1982)
GB/T 1047-2005 "Pipework Components--Definition and Selection of DN (Nominal Size)" (ISO 6708: 1995, MOD)
GB/T 1048-2005 "Pipework Components--Definition and Selection of PN" (ISO/CD 7268 : 1996, MOD)
GB/T 1220-1992 "Stainless Steel Bars"
GB/T 3077-1999 "Alloy Structure Steels"
GB/T 3098.1-2000 "Mechanical Properties of Fasteners-Bolts, Screws and Studs" (idt ISO 898-1: 1999)
GB/T 3098.6-2000 "Mechanical Properties of Corrosion-resistant Stainless-steel Fasteners-Part 1: Bolts, Screws and Studs" (idt ISO 3506-1: 1997)
GB/T 3287-2000 "Malleable Cast Iron Pipe Fittings" (eqv ISO 49: 1994)
GB/T 3420-1982 "Gray Iron Castings for Pipe Fittings"
GB/T 3422-1982 "Cast-iron Pressure Pipe Made by Continuous Casting Process"
GB/T 3985-1995 "Asbestos-rubber Sheets"
GB/T 5782-2000 "Hexagon Head Bolts" (eqv ISO 4014: 1999)
GB/T 6170-2000 "Hexagon Nuts, Style 1" (eqv ISO 4032: 1999)
GB/T 6175-2000 "Hexagon Nuts, Style 2" (eqv ISO 4033: 1999)
GB/T 7233-1987 "Methods for Ultrasonic Testing and for Specifying Quality Levels of Steel Castings"
GB/T 7306.1- 2000 "Pipe Threads with 55 Degree Thread Angle Where Pressure-tight Joints are Made on the Threads--Part 1: Parallel Internal and Taper External Threads" (eqv ISO 7-1: 1994)
GB/T 7306.2-2000 "Pipe Threads with 55 Degree Thread Angle Where Pressure-tight Joints are Made on the Threads--Part 2: Taper Internal and External Threads" (eqv ISO 7-1: 1994)
GB/T 9065-1988 "Connection Dimension of Hydraulic Hose Joints"
GB/T 9711.1-1997 "Petroleum and Natural Gas Industries-Steel Pipe for Pipelines-Technical Deivery Conditions-Part 1: Pipes of Requirement Class A" (eqv ISO 3183-1: 1996)
GB/T 12220-1989 "General Purpose Industrial Valves-Marking" (idt ISO 5209: 1977)
GB/T 12221-2005 "Metal calves--Face to Face, End to End, Center to Face and Center to End Dimensions" (ISO 5758: 1982, MOD)
GB/T 12224-2005 "General Requirements for Industrial Steel Valves"
GB/T 12232-2005 "General Purpose Industrial Valve-Flanged Iron Gate Valves"
GB/T 12233-2006 "General Purpose Industrial Valves-Casting Iron Globe Valves and Lift Check Valves"
GB/T 12234-1989 "General Purpose Industrial Valves-Flanged and Butt-weld Steel Gate Valves"
GB/T 12235-1989 "General Purpose Industrial Valves-Flanged Steel Globe Valves and Lift Check Valves"
GB/T 12236-1989 "General Purpose Industrial Valves-Steel Swing Check Valve"
GB/T 12237-1989 "General Purpose Industrial Valves-Flanged and Butt-weld End Steel Ball Valves"
GB/T 12238-1989 "General Purpose Industrial Valve-Flanged and Wafer Butterfly Valves"
GB/T 12239-1989 "General Purpose Industrial Valves-Diaphragm Valves"
GB/T 12240-1989 "General Purpose Industrial Valves-Iron Plug Valve"
GB/T 12241-2005 "Safety Valves--General Requirements" (ISO 4126-1: 1991, MOD)
GB/T 12243-2005 "Spring Loaded Safety Valves"
GB/T 12246-2006 "Pilot-operated Reducing Valves"
GB/T 12459-2005 "Steel Butt-welding Seamless Pipe Fittings"
GB/T 12716-2002 "Pipe Threads with the Thread Angle of 60 Degrees Where Pressure-tight Joints are Made on the Threads"
GB/T 12777-1999 "General Specification for Metal Bellows Expansion Joints"
GB/T 13295-2003 "Ductile Iron Pipes, Fittings and Accessories for Water or Gas Applications" (ISO 2531: 1998, MOD)
GB/T 13401-2005 "Steel Plate Butt-welding Pipe Fittings"
GB/T 13402-1992 "Large-diameter Carbon Steel Pipe Flanges"
GB/T 13403-1992 "Gaskets for Large-diameter Carbon Steel Pipe Flanges"
GB/T 13927-1992 "Pressure Testing for General Purpose Valves" (neq ISO 5208: 1982)
GB/T 13932-1992 "General Purpose Industrial Valves-Cast Iron Swing Check Valves"
GB/T 14383-1993 "Forged Steel Socket Welding Pipe Fittings"
GB/T 14626-1993 "Forged Steel Threaded Pipe Fittings"
GB/T 15185-1994 "Cast Iron and Copper Alloy Ball Valves"
GB/T 17116.1-1997 "Pipe Supports and Hangers-Part 1: Technical Specification"
GB/T 17116.2-1997 "Pipe Supports and Hangers-Part 2: Pipe Attachments"
GB/T 17116.3-1997 "Pipe Supports and Hangers-Part 3: Middle Connection Attachments and Building Structure Attachments"
GB/T 17185-1997 "Steel Pipe Fittings for Flanged Joint"
GB/T 17241-1998 "Cast Iron Pipe Flanges" (neq ISO 7005: 1988)
GB/T 17395-1998 "Dimensions, Shapes, Masses and Tolerances of Seamless Steel Tubes" (neq ISO 1127: 1992)
GB/T 18615-2002 "Non-alloyed and Stainless Steel Fittings for Corrugated Flexible Metallic Hoses" (neq ISO 10806: 1994)
GB/T 19326-2003 "Forged Branch Outlet Fittings-Socket Welding, Threaded and Butt-welding Ends"
GB/T 20801.1-2006 "Pressure Piping Code-Industrial Piping-Part 1: General"
GB/T 20801.2-2006 "Pressure Piping Code-Industrial Piping-Part 2: Materials"
GB/T 20801.4-2006 "Pressure Piping Code-Industrial Piping- Part 4: Fabrication and Assembly"
GB/T 20801.5-2006 "Pressure Piping Code-Industrial Piping-Part 5: Inspection and Testing"
HG/T 3651-1999 "Unalloyed Titanium and Titanium Alloy Butt-welding Seamless Pipe Fittings"
HG 20553-1993 "Seamless and Welded Pipe Dimension Selection Serials for Chemical Industry Piping"
HG 20592~20604 "Steel Tube Flanges (European System)"
HG 20615~20625 "Steel Tube Flanges (American System)"
HG 20605 "Welded Steel Pipe Flange Joints and Groove Size (European System)"
HG 20606 "Nonmetallic Flat Gaskets for Steel Tube Flanges (European System)"
HG 20607 "Polytetrafluoroethylene Envelope Gaskets for Steel Tube Flanges (European System)"
HG 20608 "Flexible Graphite Compound Gaskets for Steel Tube Flanges (European System)"
HG 20609 "Metal Jacketed Gaskets for Steel Tube Flanges (European System)"
HG 20610 "Spiral Wound Gaskets for Steel Tube Flanges (European System)"
HG 20611 "Grooved Compound Gaskets for Use with Steel Pipe Flanges (European System)"
HG 20612 "Metal Ring Gaskets for Steel Tube Flanges (European System)"
HG 20613 "Fasteners Used for Steel Pipe Flanges (European System)"
HG 20626 "Welded Steel Pipe Flange Joints and Groove Size (American System)"
HG 20627 "Nonmetallic Flat Gaskets for Steel Tube Flanges (American System)"
HG 20628 "Polytetrafluoroethylene Envelope Gaskets for Steel Tube Flanges (American System)"
HG 20629 "Flexible Graphite Compound Gaskets for Steel Tube Flanges (American System)"
HG 20630 "Metal Jacketed Gaskets for Steel Tube Flanges (American System)"
HG 20631 "Spiral Wound Gaskets for Steel Tube Flanges (American System)"
HG 20632 "Grooved Compound Gaskets for Use with Steel Pipe Flanges (American System)"
HG 20633 "Metal Ring Gaskets for Steel Tube Flanges (American System)"
HG 20634 "Metal Ring Gaskets for Steel Tube Flanges (American System)"
HG 21547-1993 "Steel Blank, Spacer Ring and Figure 8 Blind Plate Used for Piping"
JB/T 2768~2778-1992 "PN16.0~32.0MPa Threaded Flanges, Pipes, Fasteners and Lens Gaskets"
JB 4708-2000 "Welding Procedure Qualification for Steel Pressure Vessels"
JB 4732-1995 "Steel Pressure Vessels-Design by Analysis"
JB/T 6439-1992 "Methods of Magnetic Particle Testing for Pressure Valve Steel Castings"
JB/T 6440-1992 "Methods of Radiographic Examination for Steel Castings Valves"
JB/T 6899-1993 "Valves Fire Test"
JB/T 6902-1993 "Methods for Liquid Penetrant Examination of Valve Steel Castings"
JB/T 7747-1995 "Needle Valve"
JB/T 7927-1999 "Valve Cast Steel Visual Quality Requirements"
JB/T 8527-1997 "Metal Seal Butterfly Valves"
JB/T 8937-1999 "Wafer Type Check Valve"
JB/T 9092-1999 "Valve Inspection and Testing"
3 Terms and Definitions
In addition to the terms and definitions stated in this Part, those established in other partsof GB/T 20801 are also applicable to this Part.
3.1
Piping system
The pipes determined under the same design conditions and interconnected.
3.2
Balanced piping system
The piping system with uniform strain distribution, no excessive strained points and the stress in direct proportion to the total displacement strain.
3.3
Fluid service
One of the design conditions of piping system, consisting of fluid property, operating conditions and other factors.
3.4
Severe cyclic conditions
The operating condition when any one of the following conditions occurs:
a) The displacement stress range SE [calculated according to Formula (37)] of the pipes, pipe components or joints in the piping system exceeds 0.8 times of the allowable stress range SA [calculated according to Formula (32) or Formula (33)], meanwhile, the equivalent cycle times N [calculated according to Formula (35)] exceeds 7,000;
b) The designers judge other operating conditions having the same effects according to their experiences.
3.5
Branch connection fitting
The integrally reinforced fittings by connecting the branch pipes onto the main pipe through butt welding connection, socket welding connection or threaded connection, such as branch pipe support and half coupling, etc.
3.6
Rating value
The pressure value of piping components as specified in standards.
3.7
Schedule number
The code number of the values of pipe wall thickness series.
3.8
Displacement strain
In the piping components, the strain produced by the displacement of piping confined points due to earthquake and wind force and the strain produced due to temperature variation is generally called as "displacement strain".
3.9
Displacement stress
The stress in piping components caused by displacement strain.
3.10
Cold spring
The predeformation applied onto the piping during the erection stage in order to compensate the possible reverse deformation of piping under the service conditions.
4 Design Conditions and Design Criteria
4.1 Design Conditions
4.1.1 Design Pressure
4.1.1.1 General requirements
The design pressure of each piping component in the piping system shall not be less than the pressure under the combination operating condition of the most rigorous pressure and temperature that may be met during the operation, however, the conditions specified in 4.2.3 are excluded. The combination operating condition of the most rigorous pressure and temperature shall take account of the possible operating conditions produced by the pressure source (such as pump and compressor), the pressure pulsation, the decomposition of unstable fluid, the failure or misoperation of static pressure head, control device and valves as well as the environmental impact.
4.1.1.2 Principle for determination of design pressure
a) As for the piping equipped with safety relief device, its design pressure shall not be less than the set pressure of the safety relief device (or the maximum marked burst pressure), however, the conditions specified in 4.1.6.1b), 4.1.6.2 and 4.1.6.3 of GB/T 20801.6-2006 are excluded;
b) Where the piping and equipments are directly connected into one single pressure system, the design pressure of the piping shall not be less than the design pressure of the equipments;
c) As for piping that is not equipped with pressure relief device or may be isolated and blocked from the pressure relief device, its design pressure shall not be less than the maximum pressure that may be produced accordingly;
d) The design pressure of the outlet piping of centrifugal pump shall not be less than the closing pressure of this pump;
e) As for the pipings used for conveying refrigerant or such low boiling point medium as liquefied hydrocarbons, the design pressure of the piping shall not be less than the maximum saturated vapor pressure that may be reached by the medium when the valves are shut off or the medium is not flowing.
f) Where the piping is divided into several separate compressed sections with separators (including jacket pipes and blanking plates), the design pressure of this separator shall not be less than the pressure under the combination operating condition of the most rigorous pressure difference and temperature that may be met by the compression chambers at both sides during the operation;
g) As for the vacuum pipe with safety control device, its design pressure shall be taken as the smaller value between 1.25 times of the maximum pressure difference and 0.1MPa, and it shall be designed according to the external pressure; as for the vacuum pipe without safety control device, the design pressure shall be taken as 0.1MPa.
4.1.2 Design Temperature
4.1.2.1 General Requirements
The design temperature of each piping component in the piping system shall be determined according to the temperature under the combination operating condition of the most rigorous pressure and temperature that may be met during the operation, and different piping components in one same piping may have different design temperature.
4.1.2.2 Principle for determination of design temperature
a) Where the medium temperature is less than 65℃, the design temperature of the piping components of the piping without thermal insulating layer is identical to the medium temperature, however, the sunshine radiation or other factors that may result in the rising of medium temperature also shall be considered; where the medium temperature larger than or equal to 65℃,the determination of the design temperature of piping components of the piping without thermal insulating layer shall meet the following requirements:
1) 95% of the medium temperature for valves, pipe, flared end and welded fittings;
2) 90% of the medium temperature for flanges, the lap joint flanges excluded;
3) 85% of the medium temperature for lap joint flanges;
4) 80% of the medium temperature for bolts;
5) The measured average wall temperature or the average wall temperature calculated according to heat transfer may also be taken.
b) The design temperature of the externally insulated piping generally is taken as the medium temperature, however, it may also be taken as the measured average wall temperature or the average wall temperature calculated according to the heat transfer, and the piping adopting with tracing pipes or jacket structures shall be considered with the influence of heating or cooling on the design temperature.
c) As for the components of the internally insulated piping, the design temperature shall be determined through calculation with heat transfer or through tests.
4.1.2.3 Minimum working temperature and maximum working temperature
For the piping design, the influence of minimum working temperature and maximum working temperature on the material selection and the flexibility analysis in 7.3.3 shall be taken into consideration.
4.1.3 Loading Condition
The following loads shall be considered in the piping design:
a) Internal pressure, external pressure or maximum pressure difference (the design pressure and the corresponding design temperature shall be taken as the loading conditions together).
b) Gravity loads:
1) Piping components, heat insulating materials as well as the other gravity loads supported by the piping;
2) Fluid weight (including the hydraulic test) as well as the ice and snow weight in cold areas.
c) Dynamic loads:
1) Wind load;
2) Seismic load;
3) Impact, pressure oscillation and flash vaporization caused by fluid flow;
4) Vibration caused by machine, wind or fluid flow;
5) Counter stress by the discharging of fluid.
d) Temperature difference loads:
1) Loads produced due to the piping restriction when the temperature changes;
2) The temperature stress produced due to the sharp change or misdistribution of temperature, for instance, the temperature stress that may be caused by the thick walled pipe or stratified flowing of fluid;
3) Loads produced due to the different expansion coefficients when the temperature changes, such as bimetal pipe, jacket pipe, nonmetallic lined pipe, etc.
e) Loads caused by the displacement of end points.
Loads caused when the pipe supports and hangers or the pipe connected equipments are displaced.
4.1.4 Additional Thickness
a) The piping design shall have adequate corrosion allowance, the corrosion allowance shall be determined according to the expected service life and the corrosion rate of medium to material, moreover, the factors, such as the erosion and local corrosion, also shall be taken into consideration.
b) To determine the minimum thickness of piping components, the allowance required for corrosion, erosion, and depth of thread or trench shall be included. The thickening of pipe wall shall be considered in order to preventing the supporting, freezing, back filling, transporting and handling from causing overload stress and deformation, by which such phenomena as damage, collapse or unstability may occur.
Contents of GB/T 20801.3-2006
Foreword IV
1 Scope
2 Normative References
3 Terms and Definitions
4 Design Conditions and Design Criteria
4.1 Design Conditions
4.1.1 Design Pressure
4.1.2 Design Temperature
4.1.3 Loading Condition
4.1.4 Additional Thickness
4.1.5 Environmental Impact
4.1.6 Buried Piping
4.2 Design Criteria
4.2.1 Pressure-Temperature Design Criteria for Piping Components
4.2.2 Pressure-Temperature Design Criteria for Piping
4.2.3 Permissible Variation Range of Pressure and Temperature
4.2.4 Allowable Stress
4.2.5 Longitudinal Weld Joint Efficiency Φw
4.2.6 Quality Coefficient Φc of Casting
5 Piping Components
5.1 Selection of Piping Components
5.1.1 General Requirements
5.1.2 Pipes and Butt Welding Fittings
5.1.3 Bent Pipes
5.1.4 Miter Elbows
5.1.5 Short Radius Elbows
5.1.6 Lap Joint
5.1.7 Branch Connection and Its Fittings
5.1.8 Flanges
5.1.9 Gaskets
5.1.10 Fasteners
5.1.11 Valves
5.2 Selection of the Connection Type of Piping Components
5.2.1 General Requirements
5.2.2 Welded Joints
5.2.3 Flange Connection
5.2.4 Expanded Joints
5.2.5 Connection of Pipe Threads Where Pressure-tight Joints Are Made on the Threads
5.2.6 Straight Thread Connection
5.2.7 Connection of Fittings of Flaring and Non-flaring Stitching Type
5.2.8 Caulking Joint
5.2.9 Special Pipe Joint
5.3 Types and Dimensions of Piping Components
6 Pressure Design of Piping Components
6.1 Straight Pipe
6.2 Bent Pipes or Elbows
6.3 Miter Elbows
6.4 Pressure Design of Pipe Flange and Blind Flange
6.5 Blanking Plate
6.6 Other Piping Components
6.7 Equal-area Reinforcement Method for Branch Connection
6.7.1 Symbols
6.7.2 Application Scope of Equal-area Reinforcement Method
6.7.3 Conditions not Requiring Reinforcement
6.7.4 Reinforcement Calculation of Branch Pipe Directly Welded on Main Pipe
6.7.5 Reinforcement Calculation of Branch Pipe Connection with Extrusion Forming Joint
6.7.6 Reinforcement Design of Branch Pipe Connection on End Socket
6.8 Calculation of Integrally-shaped Tee Joint with Pressure Area Method
7 Piping Stress Analysis
7.1 General Requirements
7.2 Loads and Load Combination
7.2.1 Load and Its Classification
7.2.2 Working conditions of load combination
7.2.3 Temporary load conditions and requirements
7.3 Stress Analysis and Strength Condition
7.3.1 Stress Strength Conditions of Permanent Load
7.3.2 Stress Strength Conditions of Combination Working Conditions of Permanent Load and Temporary Load
7.3.3 Flexibility analysis
7.3.4 Determination of Support Counter Force
7.4 Pipe Supports and Hangers
7.4.1 General Requirements
7.4.2 Material Requirements
7.4.3 Design Requirements
7.4.4 Arrangement requirements
Appendix A (Informative) International Standards for Petroleum and Chemical Valves
Appendix B (Informative) Examples of Calculation
Appendix C (Normative) Flexibility Factor and Stress Enhancement Coefficient
Appendix D (Informative) Calculation of Wind Load and Seismic Load
D.1 Calculation of Horizontal Wind Power
D.2 Calculation of Horizontal Seismic Force and Seismic Bending Moment
Appendix E (Informative) Analysis on Dynamic Loads for the Opening and Closing of Valves in Piping System
E.1 Quick Closing of Valves
E.2 Opening of Relief Valves
Appendix F (Normative) Expansion Joint
F.1 Requirements for Piping Design
F.1.1 Design Conditions of Expansion Joint
F.1.2 Piping Design Requirements
F.2 Requirements for Expansion Joint Manufacturer
F.2.1 Design of Expansion Joint
F.2.2 Manufacture, Inspection and Pressure Test of Expansion Joint
Appendix G (Informative)Computation of Reinforcement with Pressure Area Method
