標準編號:	GB/T 20801.3-2020
中文名稱:	壓力管道規范 工業管道 第3部分：設計和計算
英文名稱:	Pressure piping code - Industrial piping - Part 3: Design and calculation
行業分類:	GB    國家標準
ICS分類:	23.040 23.040    管道部件和管道 23.040
發布機構:	國家市場監督管理總局 國家標準化管理委員會
發布日期:	2020-11-19
實施日期:	2021-6-1
標準狀態:	valid
替代舊標準:	GB/T 20801.3-2006 壓力管道規范 工業管道 第3部分：設計和計算
翻譯語言:	英文
文件格式:	PDF
中文字符數:	95000 字
翻譯價格(元):	5600.0
交付時間:	付款后 1 個工作日

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

壓力管道規范 工業管道 第3部分：設計和計算 1 范圍 GB／T 20801的本部分規定了壓力管道的設計和計算的基本要求，這些基本要求包括設計條件、設計準則、管道組成件及其壓力設計、管道應力分析等方面的規定。 本部分適用于GB／T 20801.1范圍界定的壓力管道的設計和計算。 2 規范性引用文件 下列文件對于本文件的應用是必不可少的。凡是注日期的引用文件，僅注日期的版本適用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改單)適用于本文件。 GB／T 150(所有部分) 壓力容器 GB／T 196 普通螺紋 基本尺寸 GB／T 197 普通螺紋 公差 GB／T 1031 產品幾何技術規范(GPS) 表面結構 輪廓法 表面粗糙度參數及其數值 GB／T 1047 管道元件 公稱尺寸的定義和選用 GB／T 1048 管道元件 公稱壓力的定義和選用 GB／T 3287 可鍛鑄鐵管路連接件 GB／T 3420 灰口鑄鐵管件 GB／T 3422 連續鑄鐵管 GB／T 3733 卡套式端直通管接頭 GB／T 3734 卡套式錐螺紋直通管接頭 GB／T 3735 卡套式端直通長管接頭 GB／T 3736 卡套式錐螺紋長管接頭 GB／T 3737 卡套式直通管接頭 GB／T 3738 卡套式可調向端彎通管接頭 GB／T 3739 卡套式錐螺紋彎通管接頭 GB／T 3740 卡套式彎通管接頭 GB／T 3741 卡套式可調向端三通管接頭 GB／T 3742 卡套式錐螺紋三通管接頭 GB／T 3743 卡套式可調向端彎通三通管接頭 GB／T 3744 卡套式錐螺紋彎通三通管接頭 GB／T 3745 卡套式三通管接頭 GB／T 3746 卡套式四通管接頭 GB／T 3747 卡套式焊接管接頭 GB／T 3748 卡套式過板直通管接頭 GB／T 3749 卡套式過板彎通管接頭 GB／T 3750 卡套式鉸接管接頭 GB／T 3751 卡套式壓力表管接頭 GB／T 3752 卡套式組合彎通管接頭 GB／T 3753 卡套式組合三通管接頭 GB／T 3754 卡套式錐密封組合彎通管接頭 GB／T 3755 卡套式錐密封組合三通管接頭 GB／T 3756 卡套式錐密封組合直通管接頭 GB／T 3757 卡套式過板焊接管接頭 GB／T 3758 卡套式管接頭用錐密封焊接接管 GB／T 3759 卡套式管接頭用連接螺母 GB／T 3760 卡套式管接頭用錐密封堵頭 GB／T 3763 管接頭用六角薄螺母 GB／T 3764 卡套 GB／T 3765 卡套式管接頭技術條件 GB／T 5625 擴口式端直通管接頭 GB／T 5626 擴口式錐螺紋直通管接頭 GB／T 5627 擴口式錐螺紋長管接頭 GB／T 5628 擴口式直通管接頭 GB／T 5629 擴口式錐螺紋彎通管接頭 GB／T 5630 擴口式彎通管接頭 GB／T 5631 擴口式可調向端彎通管接頭 GB／T 5632 擴口式組合彎通管接頭 GB／T 5633 擴口式可調向端三通管接頭 GB／T 5634 擴口式組合彎通三通管接頭 GB／T 5635 擴口式錐螺紋三通管接頭 GB／T 5637 擴口式可調向端彎通三通管接頭 GB／T 5638 擴口式組合三通管接頭 GB／T 5639 擴口式三通管接頭 GB／T 5641 擴口式四通管接頭 GB／T 5642 擴口式焊接管接頭 GB／T 5643 擴口式過板直通管接頭 GB／T 5644 擴口式過板彎通管接頭 GB／T 5645 擴口式壓力表管接頭 GB／T 5646 擴口式管接頭管套 GB／T 5647 擴口式管接頭用A型螺母 GB／T 5648 擴口式管接頭用B型螺母 GB／T 5649 管接頭用鎖緊螺母和墊圈 GB／T 5650 擴口式管接頭用空心螺栓 GB／T 5651 擴口式管接頭用密合墊 GB／T 5652 擴口式管接頭擴口端尺寸 GB／T 5653 擴口式管接頭技術條件 GB／T 5782 六角頭螺栓 GB／T 6170 1型六角螺母 GB／T 6175 2型六角螺母 GB／T 7306.1 55°密封管螺紋 第1部分：圓柱內螺紋與圓錐外螺紋 GB／T 7306.2 55°密封管螺紋 第2部分：圓錐內螺紋與圓錐外螺紋 GB／T 8464 鐵制和銅制螺紋連接閥門 GB／T 9065.1 液壓軟管接頭 第1部分：O形圈端面密封軟管接頭 GB／T 9065.2 液壓軟管接頭 第2部分：24°錐密封端軟管接頭 GB／T 9065.5 液壓軟管接頭 第5部分：37°擴口端軟管接頭 GB／T 9124.1 鋼制管法蘭 第1部分：PN系列 GB／T 9124.2 鋼制管法蘭 第2部分：Class系列 GB／T 9711 石油天然氣工業 管線輸送系統用鋼管 GB／T 12220 工業閥門 標志 GB／T 12221 金屬閥門 結構長度 GB／T 12224 鋼制閥門 一般要求 GB／T 12232 通用閥門 法蘭連接鐵制閘閥 GB／T 12233 通用閥門 鐵制截止閥與升降式止回閥 GB／T 12234 石油、天然氣工業用螺柱連接閥蓋的鋼制閘閥 GB／T 12235 石油、石化及相關工業用鋼制截止閥和升降式止回閥 GB／T 12236 石油、化工及相關工業用的鋼制旋啟式止回閥 GB／T 12237 石油、石化及相關工業用的鋼制球閥 GB／T 12238 法蘭和對夾連接彈性密封蝶閥 GB／T 12239 工業閥門 金屬隔膜閥 GB／T 12240 鐵制旋塞閥 GB／T 12241 安全閥 一般要求 GB／T 12243 彈簧直接載荷式安全閥 GB／T 12246 先導式減壓閥 GB／T 12459—2017 鋼制對焊管件 類型與參數 GB／T 12716 60°密封管螺紋 GB／T 12777 金屬波紋管膨脹節通用技術條件 GB／T 13295 水及燃氣用球墨鑄鐵管、管件和附件 GB／T 13402 大直徑鋼制管法蘭 GB／T 13927 工業閥門 壓力試驗 GB／T 13932 鐵制旋啟式止回閥 GB／T 14383 鍛制承插焊和螺紋管件 GB／T 17116(所有部分) 管道支吊架 GB／T 17185 鋼制法蘭管件 GB／T 17186.1 管法蘭連接計算方法 第1部分：基于強度和剛度的計算方法 GB／T 17241 鑄鐵管法蘭 GB／T 17395 無縫鋼管尺寸、外形、重量及允許偏差 GB／T 18615 波紋金屬軟管用非合金鋼和不銹鋼接頭 GB／T 19326 鍛制承插焊、螺紋和對焊支管座 GB／T 20801.1—2020 壓力管道規范 工業管道 第1部分：總則 GB／T 20801.2—2020 壓力管道規范 工業管道 第2部分：材料 GB／T 20801.4—2020 壓力管道規范 工業管道 第4部分：制作與安裝 GB／T 20801.5—2020 壓力管道規范 工業管道 第5部分：檢驗與試驗 GB／T 20801.6—2020 壓力管道規范 工業管道 第6部分：安全防護 GB／T 26480 閥門的檢驗和試驗 GB／T 26481 閥門的逸散性試驗 GB／T 29168.1 石油天然氣工業 管道輸送系統用感應加熱彎管、管件和法蘭 第1部分：感應加熱彎管 GB／T 29168.2 石油天然氣工業 管道輸送系統用感應加熱彎管、管件和法蘭 第2部分：管件 GB／T 29168.3 石油天然氣工業 管道輸送系統用感應加熱彎管、管件和法蘭 第3部分：法蘭 GB／T 32294 鍛制承插焊和螺紋活接頭 GB／T 38343 法蘭接頭安裝技術規定 HG／T 3651 鈦制對焊無縫管件 HG／T 20553 化工配管用無縫及焊接鋼管尺寸選用系列 HG／T 20592 鋼制管法蘭(PN系列) HG／T 20606 鋼制管法蘭用非金屬平墊片(PN系列) HG／T 20607 鋼制管法蘭用聚四氟乙烯包覆墊片(PN系列) HG／T 20609 鋼制管法蘭用金屬包覆墊片(PN系列) HG／T 20610 鋼制管法蘭用纏繞式墊片(PN系列) HG／T 20611 鋼制管法蘭用具有覆蓋層的齒形組合墊(PN系列) HG／T 20612 鋼制管法蘭用金屬環形墊(PN系列) HG／T 20613 鋼制管法蘭用緊固件(PN系列) HG／T 20614 鋼制管法蘭、墊片、緊固件選配規定(PN系列) HG／T 20615 鋼制管法蘭(Class系列) HG／T 20623 大直徑鋼制管法蘭(Class系列) HG／T 20627 鋼制管法蘭用非金屬平墊片(Class系列) HG／T 20628 鋼制管法蘭聚四氟乙烯包覆墊片(Class系列) HG／T 20630 鋼制管法蘭用金屬包覆墊片(Class系列) HG／T 20631 鋼制管法蘭纏繞式墊片(Class系列) HG／T 20632 鋼制管法蘭用具有覆蓋層的齒形組合墊(Class系列) HG／T 20633 鋼制管法蘭用金屬環形墊(Class系列) HG／T 20634 鋼制管法蘭用緊固件(Class系列) HG／T 20635 鋼制管法蘭、墊片、緊固件選配規定(Class系列) HG／T 21547 管道用鋼制插板、墊環、8字盲板系列 JB／T 2768 閥門零部件 高壓管子、管件和閥門端部尺寸 JB／T 2769 閥門零部件 高壓螺紋法蘭 JB／T 2772 閥門零部件 高壓盲板 JB／T 2776 閥門零部件 高壓透鏡墊 JB／T 2778 閥門零部件 高壓管件和緊固件溫度標記 JB 4732 壓力容器分析設計標準 JB／T 6439 閥門受壓件磁粉探傷檢驗 JB／T 6440 閥門受壓鑄鋼件射線照相檢驗 JB／T 6899 閥門的耐火試驗 JB／T 6902—2008 閥門液體滲透檢測 JB／T 6903—2008 閥門鍛鋼件超聲波檢查方法 JB／T 7747 針形截止閥 JB／T 7927—2014 閥門鑄鋼件外觀質量要求 JB／T 8527 金屬密封蝶閥 JB／T 8937 對夾式止回閥 NB／T 47014 承壓設備焊接工藝評定 SH／T 3419 石油化工鋼制異徑短節 SH／T 3425 鋼制管道用盲板技術標準 ISO 15848-1 工業閥門 散逸性介質泄漏的測量、試驗和鑒定程序 第1部分：閥門的分類體系和型式試驗鑒定程序(Industrial valves—Measurement，test and qualification procedures for fugitive emissions—Part 1：Classification system and qualification procedures for type testing of valves) API 600 鋼制閘閥 法蘭連接端和對焊端、螺栓連接閥蓋(Steel Gate—Valves Flanged and Butt-welding Ends，Bolted Bonnets) ASME BPV Code Ⅷ-2 ASME鍋爐及壓力容器規范Ⅷ第2冊壓力容器建造另一規則(ASME BPVC Section Ⅷ—Rules for Construction of Pressure Vessels Division 2 Alternative Rules) ASME B16.9 工廠制造的軋制對焊管件(Factory Made Wrought Butt-welding Fittings) ASME B16.11 承插焊和螺紋鍛制管件(Forged Fittings，Socket-welding and Threaded) ASME B36.10M 無縫和焊接鋼管(Welded and Seamless Wrought Steel Pipe) ASME B36.19M 不銹鋼鋼管(Stainless Steel Pipe) 3 術語和定義 GB／T 20801.1—2020、GB／T 20801.2—2020、GB／T 20801.4—2020、GB／T 20801.5—2020和GB／T 20801.6—2020界定的以及下列術語和定義適用于本文件。 3.1 管道系統 piping system 由同一設計條件確定且相互連接的管道。 3.2 高溫蠕變工況 elevated temperature fluid service 材料使用溫度處于焊接接頭高溫強度降低系數W小于1(見4.2.7及表5)的工況，相當于工作溫度處于由材料長期強度決定許用應力溫度范圍的工況。 3.3 流體工況 fluid service 涉及管道系統應用的綜合性術語，綜合考慮流體性質、操作條件和其他因素，構成管道系統設計的基礎。 3.4 劇烈循環工況 severe cyclic conditions 發生以下情況之一的工況： a) 管道系統中的管子、管道元件或接頭中的位移應力范圍SE[按式(39)計算]超過許用應力范圍SA[按式(34)或式(35)計算]的0.8倍，同時當量循環次數N[按式(37)計算]超過7000； b) 設計人員根據經驗判定的其他具有相同效應[位移應力范圍SE接近許用應力范圍SA，且許用應力范圍折減系數f(按式(36)計算或通過圖12查得)接近1.0的工況。 3.5 支管連接管件 branch connection fitting 通過對焊連接、承插焊連接、螺紋連接，將支管連接于主管的整體補強管件。 注：如支管座、半管接頭等。 3.6 額定值 rating value 標準規定的管道組成件壓力值。 3.7 管標號 schedule number 管子壁厚系列的數值代號。 3.8 位移應變 displacement strain 在管道組成件中，由管道約束點發生位移、端點附加位移所產生的應變以及因溫度變化所產生的應變。 3.9 位移應力 displacement stress 管道組成件中由位移應變引起的應力。 3.10 管部 structural attachments；attachment of support on piping 采用焊接、螺栓連接或卡箍方式與管道或其絕緣層直接連接的支吊架零件的總稱。 3.11 最低設計溫度 design minimum temperature 預期工況中組件的最低溫度，按此溫度確定特殊設計要求和材料評定要求。 3.12 強韌型鐵素體耐熱鋼 creep strength enhanced ferritic steels；CSEF 通過析出強化和細晶化提高蠕變斷裂強度的鉻鉬鐵素體鋼。 注：通常包括91、92、911、122和23鉻鉬鐵素體鋼。 3.13 揮發性有機物 volatile organic compounds；VOC 參與大氣光化學反應的有機化合物或任何能向大氣釋放有機化合物的符合以下任一條件的有機液體： a) 20℃時，揮發性有機液體的真實蒸氣壓大于0.3 kPa； b) 20℃時，空氣與有機化合物的混合物中，真實蒸氣壓大于0.3 kPa的純有機化合物的總質量分數等于或者高于20％，參見GB 31570和GB 31571。 4 設計條件和設計準則 4.1 設計條件 4.1.1 設計壓力 4.1.1.1 一般規定 4.1.1.1.1 管道系統中每個管道組成件的設計壓力，應不小于在操作中可能遇到的最苛刻的壓力和溫度組合工況下的壓力，但4.2.3規定的情況除外。 4.1.1.1.2 最苛刻的工況導致管道組成件具有最大厚度和最高壓力等級。 4.1.1.1.3 最苛刻的壓力和溫度組合工況應考慮壓力源(如泵、壓縮機)、壓力脈動、不穩定流體的分解、靜壓頭、控制裝置和閥門的失效或操作失誤、環境影響等可能產生的運行條件。 4.1.1.2 設計壓力的確定原則 4.1.1.2.1 裝有安全泄放裝置的管道，其設計壓力應不小于安全泄放裝置的設定壓力(或最大標定爆破壓力)，但GB／T 20801.6—2020中4.1.5a)2)和4.1.5c)規定的情況除外。 4.1.1.2.2 未設置壓力泄放裝置或可能發生與壓力泄放裝置隔離、堵塞的管道，其設計壓力應不小于可能因此而產生的最大壓力。 4.1.1.2.3 當管道與設備直接連接作為一個壓力系統時，管道的設計壓力應不小于設備的設計壓力。 4.1.1.2.4 離心泵出口管道的設計壓力應不小于泵的關閉壓力。 4.1.1.2.5 輸送制冷劑、液化烴類低沸點介質的管道，其設計壓力應不小于閥門切斷時或介質不流動時介質可能達到的最大壓力。 4.1.1.2.6 當管道被分隔件(包括夾套管、盲板等)分隔為幾個單獨的受壓段時，該分隔件的設計壓力應不小于在操作中兩側受壓室可能遇到的最苛刻的壓差和溫度組合工況的壓力。 4.1.1.2.7 裝有安全控制裝置的真空管道，設計壓力取最大壓差的1.25倍或0.1 MPa中的較小值，并按外壓條件進行設計；對于沒有安全控制裝置的真空管道，設計壓力取0.1MPa。 4.1.2 設計溫度 4.1.2.1 一般規定 4.1.2.1.1 管道系統中每個管道組成件的設計溫度應按操作中可能遇到的最苛刻的壓力和溫度組合工況的溫度確定。 4.1.2.1.2 同一管道中的不同管道組成件的設計溫度可以不同。 4.1.2.1.3 確定設計溫度時，應考慮流體溫度、環境溫度、陽光輻射、加熱或冷卻介質的溫度以及管道隔熱、傳熱的影響。 4.1.2.2 設計溫度的確定原則 4.1.2.2.1 對無外隔熱層的管道，介質溫度低于65℃時，管道組成件的設計溫度與介質溫度相同，但應考慮陽光輻射或其他可能導致介質溫度升高的因素；介質溫度高于或等于65℃時，管道組成件的設計溫度確定應符合以下規定： a) 對于閥門、管子、翻邊端部和焊接管件，取介質溫度的95％； b) 對于松套法蘭以外的法蘭，取介質溫度的90％； c) 對于松套法蘭，取介質溫度的85％； d) 對于螺栓，取介質溫度的80％； e) 也可以取實測的平均壁溫或根據傳熱計算得到的平均壁溫。 4.1.2.2.2 外部隔熱管道的設計溫度一般取介質溫度，但也可以取實測的平均壁溫或根據傳熱計算得到的平均壁溫，采用伴管或夾套結構的管道應考慮加熱或冷卻對設計溫度的影響。 4.1.2.2.3 內部隔熱管道的管道組成件，設計溫度應按傳熱計算或試驗確定。 4.1.2.3 最低設計溫度 管道設計時應考慮最低設計溫度對管道設計、材料選用和7.5.5應力分析的影響。 4.1.3 荷載條件 4.1.3.1 持久荷載 持久荷載系指作用于管道的載荷，包括： a) 介質壓力：管道內壓、外壓或最大壓差(設計壓力應與對應的設計溫度一起作為荷載條件)。 b) 重力荷載：管道設計應計入的重力荷載包括： 1) 靜荷載：管道組成件、隔熱材料重量以及施加在管道上由管道支承的其他永久性荷載； 2) 活荷載：輸送介質的重量或液壓試驗介質的重量以及由于環境和操作條件造成的冰、雪的重量。 4.1.3.2 偶然性荷載 偶然性荷載系指短時間作用于管道的載荷，包括： a) 風荷載：設計室外管道時，應計算風荷載，其計算方法可參見附錄A； b) 地震荷載：設計管道時，應計算由地震引起的水平力，其計算方法可參見附錄A； c) 流體排放反力：由于流體的減速或排放而產生的反作用力，管道的設計、布置、支承應能承受此反作用力。 4.1.3.3 溫度及位移荷載 溫度及位移載荷系指管道系統由溫度及位移而引起的荷載，包括： a) 因約束產生的荷載：溫度變化時，因管道受約束使管道不能自由熱脹冷縮而產生的軸向力和力矩； b) 端點位移引起的荷載：管道支吊架或管道連接的設備發生位移引起的荷載； c) 由于膨脹特性不同產生的荷載：材料熱脹系數差異導致熱膨脹的不同而產生的荷載，如雙金屬管道、夾套管道、非金屬襯里管道等； d) 溫度梯度形成的荷載：因溫度劇變或分布不均勻而在管壁中產生的應力所形成的荷載，如高溫流體通過厚壁管或流體分層流動而產生的管道彎曲。 4.1.3.4 循環荷載 循環荷載系指管道系統由壓力循環、熱循環以及其他循環引起的疲勞的荷載。 4.1.3.5 沖擊 沖擊系指外部或內部條件引起的沖擊力，包括介質流動導致的沖擊、介質流速的變化、壓力波動、液體閃蒸、水擊、液體或固體的猛擊、暴漲和噴發。 4.1.3.6 振動 振動系指由沖擊、壓力脈動、紊流渦流、壓縮機共振以及風荷載引起的振動。管道設計、布置、支承應能消除過度和有害的振動影響。 4.1.4 厚度附加量 4.1.4.1 腐蝕裕量 管道設計應有足夠的腐蝕裕量，腐蝕裕量應根據預期的使用壽命和介質對材料的腐蝕速率來確定，還應考慮沖蝕和局部腐蝕等因素。 4.1.4.2 其他附加量 確定管道組成件最小厚度時，應包括腐蝕、沖蝕、螺紋深度或溝槽深度所需的裕量。為防止因支承、結冰、回填、運輸和裝卸等引起的超載應力和變形，從而可能產生的損壞、垮塌或失穩等現象，應考慮增加管壁厚度。 4.1.5 環境影響 4.1.5.1 壓力 對于被隔斷管道中的流體，應考慮因受環境加熱產生膨脹所導致的壓力升高或因受環境冷卻而導致管道的壓力下降甚至真空。 4.1.5.2 溫度 當管道系統的設計溫度低于0℃時，應考慮因表面冷凝、冰凍而引起的閥門、泄壓裝置或排放管道故障以及低溫對柔性分析和材料選用等的影響。 4.1.6 管道布置和特定管道系統的設計要求 管道布置和特定管道系統，如泄放管道、埋地管道、可燃介質和有毒介質管道、蒸汽管道、低溫管道、管道的隔熱和靜電接地設計要求等參見附錄B。 4.2 設計準則 4.2.1 管道組成件壓力-溫度設計準則 管道組成件的壓力-溫度設計應采用4.2.1.1～4.2.1.4規定的方法之一。 4.2.1.1 壓力-溫度額定值方法 管道組成件的壓力-溫度額定值的確定應符合下列規定： a) 除本部分另有規定外，表13中已規定壓力-溫度額定值的管道組成件，其設計溫度下的最大允許工作壓力按相關標準規定的壓力-溫度額定值； b) 如設計溫度高于表13中相關標準給出的溫度額定值，但不高于GB／T 20801.2規定的材料使用溫度上限者，設計者可根據相關溫度下的材料許用應力折算； c) 對于表13中僅標明公稱壓力的管道組成件，設計溫度下的最大允許工作壓力可根據設計溫度和常溫下的材料許用應力折算； d) 表13中未列入的管道組成件，其適用的壓力-溫度值應符合5.3.3的規定。 4.2.1.2 壓力設計方法 管道組成件的壓力設計應符合下列規定： a) 直管、斜接彎頭、彎管、盲板、非標法蘭和非標對焊管件等管道組成件應按第6章設計； b) 對于按壁厚系列規定的承插焊管件和螺紋管件，其設計溫度下的最大允許工作壓力應不大于具有相同壁厚系列和相同許用應力的無縫直管按有效厚度確定的最大允許工作壓力； c) 支管與主管直接連接的壓力設計應符合6.7、6.8的規定。 4.2.1.3 驗證性壓力試驗方法 管道組成件的驗證性壓力試驗應符合下列規定： a) 對于表13中的對焊管件，如未按4.2.1.2a)進行壓力設計，可進行驗證性壓力試驗并在驗證性壓力試驗的覆蓋范同內按4.2.1.2b)確定其設計溫度下的最大允許工作壓力； b) 其他管道組成件也可根據驗證性壓力試驗確定其最大允許工作壓力。 4.2.1.4 其他方法 除4.2.1.1、4.2.1.2和4.2.1.3規定的方法外，管道組成件的最大允許工作壓力也可以采用對比經驗分析、應力分析或實驗應力分析方法確定。 4.2.2 管道系統壓力-溫度設計準則 管道系統的壓力-溫度設計應符合下列規定： a) 除4.2.3的規定外，管道的設計壓力應不大于該管道系統中所有管道組成件按4.2.1確定的設計溫度下的最大允許工作壓力的最小值； b) 不同流體工況的管道連接時，分隔閥門的額定值應按苛刻工況確定。但位于閥門任一側的管道均應按相應的工況條件進行設計。 4.2.3 壓力和溫度的允許變動范圍 4.2.3.1 確定設計壓力和設計溫度時，應考慮管道系統運行時發生的壓力和溫度的變動。 4.2.3.2 GC1級管道壓力和溫度不得超出設計范圍。 4.2.3.3 除符合下列各項條件以及4.2.3.4的要求外，GC2和GC3級管道應按壓力和溫度變動中的最苛刻組合確定設計條件： a) 管道系統中沒有鑄鐵或其他脆性金屬材料的管道組成件； b) 由壓力產生的管道名義應力不超過材料在相應溫度下的屈服強度； c) 總應力符合7.5.5的規定； d) 管道系統預期壽命內，超過設計條件的壓力-溫度變化的總次數不大于1000次； e) 壓力變動的上限值不大于管道系統的試驗壓力； f) 持續和周期性變動不改變管道系統中所有管道組成件的操作安全性能； g) 溫度變動的下限值不小于GB／T 20801.2規定的材料最低使用溫度； h) 閥門閉合元件的壓力差不超過閥門制造商規定的最大額定壓力差。 4.2.3.4 超過設計條件的壓力偶然變動應限制在下列任一范圍內： a) 壓力超過相應溫度下的壓力額定值或由壓力產生的管道名義應力超過材料許用應力值的幅度和頻率應滿足下列條件之一： 1) 變動幅度不大于33％，每次變動時間不超過10 h，且每年累計變動時間不超過100 h； 2) 變動幅度不大于20％，每次變動時間不超過50 h，且每年累計變動時間不超過500 h。 b) 當波動為自限(例如壓力泄放)時，在每次變動時間不超過50h且每年累計變動時間不超過500h條件下，壓力額定值變動幅度不大于20%，或管道名義應力超過材料許用應力值的幅度不大于20%。 4.2.4 許用應力 4.2.4.1 金屬材料許用應力和螺栓材料許用應力應符合GB／T 20801.2—2020表A.1和表A.2的規定。 注：表中許用應力值未包括材料的縱向焊接接頭系數φW、焊接接頭高溫強度降低系數W和鑄件質量系數φC(見表4)。 4.2.4.2 GB／T 20801.2—2020表A.1和表A.2以外的金屬材料和螺栓材料應按表1和表2規定的準則確定各自的許用應力。 4.2.4.3 拉伸許用應力按4.2.4.1和4.2.4.2取值。 4.2.4.4 壓縮許用應力應符合結構穩定性的要求，且不大于拉伸許用應力。 4.2.4.5 剪切許用應力取拉伸許用應力的80%，接觸許用應力取拉伸許用應力的160%。 4.2.5 縱向焊接接頭系數φW 管子和對焊管件的縱向焊接接頭系數φW應按表3規定的準則或GB／T 20801.2—2020表A.3確定。 表1 金屬材料許用應力準則 材料 許用應力應不大于下列各值中的最小值 抗拉強度下限值 Rm／MPa 屈服強度下限值 ReL(Rp0.2)／MPa 設計溫度下屈服強度 持久強度平均值或持久強度最低值 或 蠕變極限 平均值 灰鑄鐵 — — — — 可鍛鑄鐵 — — — — 球墨鑄鐵，碳鋼、合金鋼、鐵素體不銹鋼、延伸率小于35%的奧氏體不銹鋼、雙相不銹鋼、鈦和鈦合金、鋁和鋁合金 ， 延伸率大于或等于35%的奧氏體不銹鋼和鎳基合金 ， a對于法蘭或其他有微量永久變形就引起泄漏或故障的場合不能采用。 表2 螺栓材料許用應力準則 材料 許用應力應不大于下列各值中的最小值 抗拉強度下限值 Rm／MPa 屈服強度下限值 ReL(Rp0.2)／MPa 設計溫度下屈服強度 持久強度平均值或持久強度最低值 或 蠕變極限 平均值 非熱處理或應變 強化的螺栓材料 ， 熱處理或應變 強化的螺栓材料 ， 注1：對于熱處理或應變強化處理的螺栓材料，許用應力取表中最小值。若該許用應力小于材料退火狀態下的許用應力，取非熱處理或應變強化(即退火狀態)螺栓材料的許用應力。 注2：表列螺栓許用應力準則僅用于非標準法蘭設計的螺栓強度要求，而螺栓安裝的目標應力可達50%～70%螺栓材料的屈服強度。 表3 縱向焊接接頭系數φW 序號 焊接型式 焊縫類型 檢查 φW 1 連續爐焊a 直縫 按材料標準規定 0.60 2 電阻焊(ERW)a 直縫或螺旋縫 按材料標準規定 0.85 3 電熔焊(EFW) 單面對接焊(帶或不帶填充金屬) 直縫或螺旋縫 按材料標準或本部分規定不作RT 0.80 局部(10%)RT 0.90 100%RT 1.00 雙面對接焊(帶或不帶填充金屬) 直縫或螺旋縫(除序號4外) 按材料標準或本部分規定不作RT 0.85 局部(10%)RT 0.90 100%RT 1.00 4 GB／T 9711電熔焊(EFW)，雙面對接焊 直縫(一條或兩條)或螺旋縫 按GB／T 9711規定 0.95 附加100%RT 1.00 a不得通過附加無損檢測來提高電阻焊(ERW)的縱向焊接接頭系數。 表4 鑄件質量系數φC及附加無損檢測要求 序號 附加無損檢測要求 鑄件質量系數φC 1 鑄件表面加工至Ra6.3，提高目視檢查的清晰度，并滿足JB／T 7927—2014中B級的要求 0.85 2 鑄件表面按JB／T 6902—2008(PT)中的4級或JB／T 6439(MT)進行著色滲透檢測或磁粉檢測 0.85 3 鑄件按JB／T 6440(RT)或JB／T 6903—2008(UT)中的2級進行射線照相或超聲檢測 0.95 4 同序號1和序號2 0.90 5 同序號1和序號3 1.00 6 同序號2和序號3 1.00 4.2.6 鑄件質量系數φC 4.2.6.1 鑄鐵件(灰鑄鐵、球墨鑄鐵、可鍛鑄鐵)的鑄件質量系數φC取1.0。 4.2.6.2 除鑄鐵外，GB／T 20801.2—2020表A.1中金屬靜態鑄件應按JB／T 7927進行外觀檢查，且不低于B級要求，鑄件質量系數取0.8。 4.2.6.3 對需要進行附加無損檢測的鑄件可取表4中的鑄件質量系數，但鑄件質量系數φC的改變并不影響管道組成件的壓力-溫度額定值。 4.2.7 焊接接頭高溫強度降低系數W 4.2.7.1 使用表5所列高溫蠕變工況的鉻鉬合金鋼、強韌型鐵素體耐熱鋼、300系奧氏體不銹鋼、800和600鎳基合金焊接接頭的長期工作強度可能低于母材。 按第6章設計承受內壓的焊接直管和彎管、彎頭、斜接彎頭、異徑管等對焊管件壁厚時，許用應力與縱向焊接接頭系數的乘積SφW還應乘以焊接接頭高溫強度降低系數W；計算由持續性荷載產生的軸向應力時，環焊縫的許用應力Sh也應乘以W。 4.2.7.2 符合下列條件之一者，可不計焊縫接頭高溫強度降低系數W： a) 評價臨時荷載(如風荷載、地震荷載)時； b) 按4.2.3評價的壓力和溫度允許變動范圍時； c) 按a)或b)條件的額定壓力或許用應力； d) 按7.5.5.3計算柔性分析的許用應力范圍SA時。 4.2.7.3 對于表5以外的材料，除4.2.7.4以外，溫度不高于510℃時，W取1.0；溫度為815℃時，W取0.5，中間數值采用線性內插法計算；溫度高于815℃時，由設計者確定W。 4.2.7.4 允許通過焊接接頭蠕變斷裂試驗確定大于表5或4.2.7.3的W值，但應符合下列規定： a) 應采用全厚度包括母材、焊縫及熱影響區的橫向焊接接頭試樣； b) 持久斷裂時間不低于1000 h。