标准编号:	GB/T 20801.3-2020
中文名称:	压力管道规范 工业管道 第3部分：设计和计算
英文名称:	Pressure piping code - Industrial piping - Part 3: Design and calculation
行业分类:	GB    国家标准
ICS分类:	23.040 23.040    管道部件和管道 23.040
发布机构:	国家市场监督管理总局 国家标准化管理委员会
发布日期:	2020-11-19
实施日期:	2021-6-1
标准状态:	valid
替代旧标准:	GB/T 20801.3-2006 压力管道规范 工业管道 第3部分：设计和计算
翻译语言:	英文
文件格式:	PDF
中文字符数:	95000 字
翻译价格(元):	5600.0
交付时间:	付款后 1 个工作日

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

压力管道规范 工业管道 第3部分：设计和计算 1 范围 GB／T 20801的本部分规定了压力管道的设计和计算的基本要求，这些基本要求包括设计条件、设计准则、管道组成件及其压力设计、管道应力分析等方面的规定。 本部分适用于GB／T 20801.1范围界定的压力管道的设计和计算。 2 规范性引用文件 下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本(包括所有的修改单)适用于本文件。 GB／T 150(所有部分) 压力容器 GB／T 196 普通螺纹 基本尺寸 GB／T 197 普通螺纹 公差 GB／T 1031 产品几何技术规范(GPS) 表面结构 轮廓法 表面粗糙度参数及其数值 GB／T 1047 管道元件 公称尺寸的定义和选用 GB／T 1048 管道元件 公称压力的定义和选用 GB／T 3287 可锻铸铁管路连接件 GB／T 3420 灰口铸铁管件 GB／T 3422 连续铸铁管 GB／T 3733 卡套式端直通管接头 GB／T 3734 卡套式锥螺纹直通管接头 GB／T 3735 卡套式端直通长管接头 GB／T 3736 卡套式锥螺纹长管接头 GB／T 3737 卡套式直通管接头 GB／T 3738 卡套式可调向端弯通管接头 GB／T 3739 卡套式锥螺纹弯通管接头 GB／T 3740 卡套式弯通管接头 GB／T 3741 卡套式可调向端三通管接头 GB／T 3742 卡套式锥螺纹三通管接头 GB／T 3743 卡套式可调向端弯通三通管接头 GB／T 3744 卡套式锥螺纹弯通三通管接头 GB／T 3745 卡套式三通管接头 GB／T 3746 卡套式四通管接头 GB／T 3747 卡套式焊接管接头 GB／T 3748 卡套式过板直通管接头 GB／T 3749 卡套式过板弯通管接头 GB／T 3750 卡套式铰接管接头 GB／T 3751 卡套式压力表管接头 GB／T 3752 卡套式组合弯通管接头 GB／T 3753 卡套式组合三通管接头 GB／T 3754 卡套式锥密封组合弯通管接头 GB／T 3755 卡套式锥密封组合三通管接头 GB／T 3756 卡套式锥密封组合直通管接头 GB／T 3757 卡套式过板焊接管接头 GB／T 3758 卡套式管接头用锥密封焊接接管 GB／T 3759 卡套式管接头用连接螺母 GB／T 3760 卡套式管接头用锥密封堵头 GB／T 3763 管接头用六角薄螺母 GB／T 3764 卡套 GB／T 3765 卡套式管接头技术条件 GB／T 5625 扩口式端直通管接头 GB／T 5626 扩口式锥螺纹直通管接头 GB／T 5627 扩口式锥螺纹长管接头 GB／T 5628 扩口式直通管接头 GB／T 5629 扩口式锥螺纹弯通管接头 GB／T 5630 扩口式弯通管接头 GB／T 5631 扩口式可调向端弯通管接头 GB／T 5632 扩口式组合弯通管接头 GB／T 5633 扩口式可调向端三通管接头 GB／T 5634 扩口式组合弯通三通管接头 GB／T 5635 扩口式锥螺纹三通管接头 GB／T 5637 扩口式可调向端弯通三通管接头 GB／T 5638 扩口式组合三通管接头 GB／T 5639 扩口式三通管接头 GB／T 5641 扩口式四通管接头 GB／T 5642 扩口式焊接管接头 GB／T 5643 扩口式过板直通管接头 GB／T 5644 扩口式过板弯通管接头 GB／T 5645 扩口式压力表管接头 GB／T 5646 扩口式管接头管套 GB／T 5647 扩口式管接头用A型螺母 GB／T 5648 扩口式管接头用B型螺母 GB／T 5649 管接头用锁紧螺母和垫圈 GB／T 5650 扩口式管接头用空心螺栓 GB／T 5651 扩口式管接头用密合垫 GB／T 5652 扩口式管接头扩口端尺寸 GB／T 5653 扩口式管接头技术条件 GB／T 5782 六角头螺栓 GB／T 6170 1型六角螺母 GB／T 6175 2型六角螺母 GB／T 7306.1 55°密封管螺纹 第1部分：圆柱内螺纹与圆锥外螺纹 GB／T 7306.2 55°密封管螺纹 第2部分：圆锥内螺纹与圆锥外螺纹 GB／T 8464 铁制和铜制螺纹连接阀门 GB／T 9065.1 液压软管接头 第1部分：O形圈端面密封软管接头 GB／T 9065.2 液压软管接头 第2部分：24°锥密封端软管接头 GB／T 9065.5 液压软管接头 第5部分：37°扩口端软管接头 GB／T 9124.1 钢制管法兰 第1部分：PN系列 GB／T 9124.2 钢制管法兰 第2部分：Class系列 GB／T 9711 石油天然气工业 管线输送系统用钢管 GB／T 12220 工业阀门 标志 GB／T 12221 金属阀门 结构长度 GB／T 12224 钢制阀门 一般要求 GB／T 12232 通用阀门 法兰连接铁制闸阀 GB／T 12233 通用阀门 铁制截止阀与升降式止回阀 GB／T 12234 石油、天然气工业用螺柱连接阀盖的钢制闸阀 GB／T 12235 石油、石化及相关工业用钢制截止阀和升降式止回阀 GB／T 12236 石油、化工及相关工业用的钢制旋启式止回阀 GB／T 12237 石油、石化及相关工业用的钢制球阀 GB／T 12238 法兰和对夹连接弹性密封蝶阀 GB／T 12239 工业阀门 金属隔膜阀 GB／T 12240 铁制旋塞阀 GB／T 12241 安全阀 一般要求 GB／T 12243 弹簧直接载荷式安全阀 GB／T 12246 先导式减压阀 GB／T 12459—2017 钢制对焊管件 类型与参数 GB／T 12716 60°密封管螺纹 GB／T 12777 金属波纹管膨胀节通用技术条件 GB／T 13295 水及燃气用球墨铸铁管、管件和附件 GB／T 13402 大直径钢制管法兰 GB／T 13927 工业阀门 压力试验 GB／T 13932 铁制旋启式止回阀 GB／T 14383 锻制承插焊和螺纹管件 GB／T 17116(所有部分) 管道支吊架 GB／T 17185 钢制法兰管件 GB／T 17186.1 管法兰连接计算方法 第1部分：基于强度和刚度的计算方法 GB／T 17241 铸铁管法兰 GB／T 17395 无缝钢管尺寸、外形、重量及允许偏差 GB／T 18615 波纹金属软管用非合金钢和不锈钢接头 GB／T 19326 锻制承插焊、螺纹和对焊支管座 GB／T 20801.1—2020 压力管道规范 工业管道 第1部分：总则 GB／T 20801.2—2020 压力管道规范 工业管道 第2部分：材料 GB／T 20801.4—2020 压力管道规范 工业管道 第4部分：制作与安装 GB／T 20801.5—2020 压力管道规范 工业管道 第5部分：检验与试验 GB／T 20801.6—2020 压力管道规范 工业管道 第6部分：安全防护 GB／T 26480 阀门的检验和试验 GB／T 26481 阀门的逸散性试验 GB／T 29168.1 石油天然气工业 管道输送系统用感应加热弯管、管件和法兰 第1部分：感应加热弯管 GB／T 29168.2 石油天然气工业 管道输送系统用感应加热弯管、管件和法兰 第2部分：管件 GB／T 29168.3 石油天然气工业 管道输送系统用感应加热弯管、管件和法兰 第3部分：法兰 GB／T 32294 锻制承插焊和螺纹活接头 GB／T 38343 法兰接头安装技术规定 HG／T 3651 钛制对焊无缝管件 HG／T 20553 化工配管用无缝及焊接钢管尺寸选用系列 HG／T 20592 钢制管法兰(PN系列) HG／T 20606 钢制管法兰用非金属平垫片(PN系列) HG／T 20607 钢制管法兰用聚四氟乙烯包覆垫片(PN系列) HG／T 20609 钢制管法兰用金属包覆垫片(PN系列) HG／T 20610 钢制管法兰用缠绕式垫片(PN系列) HG／T 20611 钢制管法兰用具有覆盖层的齿形组合垫(PN系列) HG／T 20612 钢制管法兰用金属环形垫(PN系列) HG／T 20613 钢制管法兰用紧固件(PN系列) HG／T 20614 钢制管法兰、垫片、紧固件选配规定(PN系列) HG／T 20615 钢制管法兰(Class系列) HG／T 20623 大直径钢制管法兰(Class系列) HG／T 20627 钢制管法兰用非金属平垫片(Class系列) HG／T 20628 钢制管法兰聚四氟乙烯包覆垫片(Class系列) HG／T 20630 钢制管法兰用金属包覆垫片(Class系列) HG／T 20631 钢制管法兰缠绕式垫片(Class系列) HG／T 20632 钢制管法兰用具有覆盖层的齿形组合垫(Class系列) HG／T 20633 钢制管法兰用金属环形垫(Class系列) HG／T 20634 钢制管法兰用紧固件(Class系列) HG／T 20635 钢制管法兰、垫片、紧固件选配规定(Class系列) HG／T 21547 管道用钢制插板、垫环、8字盲板系列 JB／T 2768 阀门零部件 高压管子、管件和阀门端部尺寸 JB／T 2769 阀门零部件 高压螺纹法兰 JB／T 2772 阀门零部件 高压盲板 JB／T 2776 阀门零部件 高压透镜垫 JB／T 2778 阀门零部件 高压管件和紧固件温度标记 JB 4732 压力容器分析设计标准 JB／T 6439 阀门受压件磁粉探伤检验 JB／T 6440 阀门受压铸钢件射线照相检验 JB／T 6899 阀门的耐火试验 JB／T 6902—2008 阀门液体渗透检测 JB／T 6903—2008 阀门锻钢件超声波检查方法 JB／T 7747 针形截止阀 JB／T 7927—2014 阀门铸钢件外观质量要求 JB／T 8527 金属密封蝶阀 JB／T 8937 对夹式止回阀 NB／T 47014 承压设备焊接工艺评定 SH／T 3419 石油化工钢制异径短节 SH／T 3425 钢制管道用盲板技术标准 ISO 15848-1 工业阀门 散逸性介质泄漏的测量、试验和鉴定程序 第1部分：阀门的分类体系和型式试验鉴定程序(Industrial valves—Measurement，test and qualification procedures for fugitive emissions—Part 1：Classification system and qualification procedures for type testing of valves) API 600 钢制闸阀 法兰连接端和对焊端、螺栓连接阀盖(Steel Gate—Valves Flanged and Butt-welding Ends，Bolted Bonnets) ASME BPV Code Ⅷ-2 ASME锅炉及压力容器规范Ⅷ第2册压力容器建造另一规则(ASME BPVC Section Ⅷ—Rules for Construction of Pressure Vessels Division 2 Alternative Rules) ASME B16.9 工厂制造的轧制对焊管件(Factory Made Wrought Butt-welding Fittings) ASME B16.11 承插焊和螺纹锻制管件(Forged Fittings，Socket-welding and Threaded) ASME B36.10M 无缝和焊接钢管(Welded and Seamless Wrought Steel Pipe) ASME B36.19M 不锈钢钢管(Stainless Steel Pipe) 3 术语和定义 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界定的以及下列术语和定义适用于本文件。 3.1 管道系统 piping system 由同一设计条件确定且相互连接的管道。 3.2 高温蠕变工况 elevated temperature fluid service 材料使用温度处于焊接接头高温强度降低系数W小于1(见4.2.7及表5)的工况，相当于工作温度处于由材料长期强度决定许用应力温度范围的工况。 3.3 流体工况 fluid service 涉及管道系统应用的综合性术语，综合考虑流体性质、操作条件和其他因素，构成管道系统设计的基础。 3.4 剧烈循环工况 severe cyclic conditions 发生以下情况之一的工况： a) 管道系统中的管子、管道元件或接头中的位移应力范围SE[按式(39)计算]超过许用应力范围SA[按式(34)或式(35)计算]的0.8倍，同时当量循环次数N[按式(37)计算]超过7000； b) 设计人员根据经验判定的其他具有相同效应[位移应力范围SE接近许用应力范围SA，且许用应力范围折减系数f(按式(36)计算或通过图12查得)接近1.0的工况。 3.5 支管连接管件 branch connection fitting 通过对焊连接、承插焊连接、螺纹连接，将支管连接于主管的整体补强管件。 注：如支管座、半管接头等。 3.6 额定值 rating value 标准规定的管道组成件压力值。 3.7 管标号 schedule number 管子壁厚系列的数值代号。 3.8 位移应变 displacement strain 在管道组成件中，由管道约束点发生位移、端点附加位移所产生的应变以及因温度变化所产生的应变。 3.9 位移应力 displacement stress 管道组成件中由位移应变引起的应力。 3.10 管部 structural attachments；attachment of support on piping 采用焊接、螺栓连接或卡箍方式与管道或其绝缘层直接连接的支吊架零件的总称。 3.11 最低设计温度 design minimum temperature 预期工况中组件的最低温度，按此温度确定特殊设计要求和材料评定要求。 3.12 强韧型铁素体耐热钢 creep strength enhanced ferritic steels；CSEF 通过析出强化和细晶化提高蠕变断裂强度的铬钼铁素体钢。 注：通常包括91、92、911、122和23铬钼铁素体钢。 3.13 挥发性有机物 volatile organic compounds；VOC 参与大气光化学反应的有机化合物或任何能向大气释放有机化合物的符合以下任一条件的有机液体： a) 20℃时，挥发性有机液体的真实蒸气压大于0.3 kPa； b) 20℃时，空气与有机化合物的混合物中，真实蒸气压大于0.3 kPa的纯有机化合物的总质量分数等于或者高于20％，参见GB 31570和GB 31571。 4 设计条件和设计准则 4.1 设计条件 4.1.1 设计压力 4.1.1.1 一般规定 4.1.1.1.1 管道系统中每个管道组成件的设计压力，应不小于在操作中可能遇到的最苛刻的压力和温度组合工况下的压力，但4.2.3规定的情况除外。 4.1.1.1.2 最苛刻的工况导致管道组成件具有最大厚度和最高压力等级。 4.1.1.1.3 最苛刻的压力和温度组合工况应考虑压力源(如泵、压缩机)、压力脉动、不稳定流体的分解、静压头、控制装置和阀门的失效或操作失误、环境影响等可能产生的运行条件。 4.1.1.2 设计压力的确定原则 4.1.1.2.1 装有安全泄放装置的管道，其设计压力应不小于安全泄放装置的设定压力(或最大标定爆破压力)，但GB／T 20801.6—2020中4.1.5a)2)和4.1.5c)规定的情况除外。 4.1.1.2.2 未设置压力泄放装置或可能发生与压力泄放装置隔离、堵塞的管道，其设计压力应不小于可能因此而产生的最大压力。 4.1.1.2.3 当管道与设备直接连接作为一个压力系统时，管道的设计压力应不小于设备的设计压力。 4.1.1.2.4 离心泵出口管道的设计压力应不小于泵的关闭压力。 4.1.1.2.5 输送制冷剂、液化烃类低沸点介质的管道，其设计压力应不小于阀门切断时或介质不流动时介质可能达到的最大压力。 4.1.1.2.6 当管道被分隔件(包括夹套管、盲板等)分隔为几个单独的受压段时，该分隔件的设计压力应不小于在操作中两侧受压室可能遇到的最苛刻的压差和温度组合工况的压力。 4.1.1.2.7 装有安全控制装置的真空管道，设计压力取最大压差的1.25倍或0.1 MPa中的较小值，并按外压条件进行设计；对于没有安全控制装置的真空管道，设计压力取0.1MPa。 4.1.2 设计温度 4.1.2.1 一般规定 4.1.2.1.1 管道系统中每个管道组成件的设计温度应按操作中可能遇到的最苛刻的压力和温度组合工况的温度确定。 4.1.2.1.2 同一管道中的不同管道组成件的设计温度可以不同。 4.1.2.1.3 确定设计温度时，应考虑流体温度、环境温度、阳光辐射、加热或冷却介质的温度以及管道隔热、传热的影响。 4.1.2.2 设计温度的确定原则 4.1.2.2.1 对无外隔热层的管道，介质温度低于65℃时，管道组成件的设计温度与介质温度相同，但应考虑阳光辐射或其他可能导致介质温度升高的因素；介质温度高于或等于65℃时，管道组成件的设计温度确定应符合以下规定： a) 对于阀门、管子、翻边端部和焊接管件，取介质温度的95％； b) 对于松套法兰以外的法兰，取介质温度的90％； c) 对于松套法兰，取介质温度的85％； d) 对于螺栓，取介质温度的80％； e) 也可以取实测的平均壁温或根据传热计算得到的平均壁温。 4.1.2.2.2 外部隔热管道的设计温度一般取介质温度，但也可以取实测的平均壁温或根据传热计算得到的平均壁温，采用伴管或夹套结构的管道应考虑加热或冷却对设计温度的影响。 4.1.2.2.3 内部隔热管道的管道组成件，设计温度应按传热计算或试验确定。 4.1.2.3 最低设计温度 管道设计时应考虑最低设计温度对管道设计、材料选用和7.5.5应力分析的影响。 4.1.3 荷载条件 4.1.3.1 持久荷载 持久荷载系指作用于管道的载荷，包括： a) 介质压力：管道内压、外压或最大压差(设计压力应与对应的设计温度一起作为荷载条件)。 b) 重力荷载：管道设计应计入的重力荷载包括： 1) 静荷载：管道组成件、隔热材料重量以及施加在管道上由管道支承的其他永久性荷载； 2) 活荷载：输送介质的重量或液压试验介质的重量以及由于环境和操作条件造成的冰、雪的重量。 4.1.3.2 偶然性荷载 偶然性荷载系指短时间作用于管道的载荷，包括： a) 风荷载：设计室外管道时，应计算风荷载，其计算方法可参见附录A； b) 地震荷载：设计管道时，应计算由地震引起的水平力，其计算方法可参见附录A； c) 流体排放反力：由于流体的减速或排放而产生的反作用力，管道的设计、布置、支承应能承受此反作用力。 4.1.3.3 温度及位移荷载 温度及位移载荷系指管道系统由温度及位移而引起的荷载，包括： a) 因约束产生的荷载：温度变化时，因管道受约束使管道不能自由热胀冷缩而产生的轴向力和力矩； b) 端点位移引起的荷载：管道支吊架或管道连接的设备发生位移引起的荷载； c) 由于膨胀特性不同产生的荷载：材料热胀系数差异导致热膨胀的不同而产生的荷载，如双金属管道、夹套管道、非金属衬里管道等； d) 温度梯度形成的荷载：因温度剧变或分布不均匀而在管壁中产生的应力所形成的荷载，如高温流体通过厚壁管或流体分层流动而产生的管道弯曲。 4.1.3.4 循环荷载 循环荷载系指管道系统由压力循环、热循环以及其他循环引起的疲劳的荷载。 4.1.3.5 冲击 冲击系指外部或内部条件引起的冲击力，包括介质流动导致的冲击、介质流速的变化、压力波动、液体闪蒸、水击、液体或固体的猛击、暴涨和喷发。 4.1.3.6 振动 振动系指由冲击、压力脉动、紊流涡流、压缩机共振以及风荷载引起的振动。管道设计、布置、支承应能消除过度和有害的振动影响。 4.1.4 厚度附加量 4.1.4.1 腐蚀裕量 管道设计应有足够的腐蚀裕量，腐蚀裕量应根据预期的使用寿命和介质对材料的腐蚀速率来确定，还应考虑冲蚀和局部腐蚀等因素。 4.1.4.2 其他附加量 确定管道组成件最小厚度时，应包括腐蚀、冲蚀、螺纹深度或沟槽深度所需的裕量。为防止因支承、结冰、回填、运输和装卸等引起的超载应力和变形，从而可能产生的损坏、垮塌或失稳等现象，应考虑增加管壁厚度。 4.1.5 环境影响 4.1.5.1 压力 对于被隔断管道中的流体，应考虑因受环境加热产生膨胀所导致的压力升高或因受环境冷却而导致管道的压力下降甚至真空。 4.1.5.2 温度 当管道系统的设计温度低于0℃时，应考虑因表面冷凝、冰冻而引起的阀门、泄压装置或排放管道故障以及低温对柔性分析和材料选用等的影响。 4.1.6 管道布置和特定管道系统的设计要求 管道布置和特定管道系统，如泄放管道、埋地管道、可燃介质和有毒介质管道、蒸汽管道、低温管道、管道的隔热和静电接地设计要求等参见附录B。 4.2 设计准则 4.2.1 管道组成件压力-温度设计准则 管道组成件的压力-温度设计应采用4.2.1.1～4.2.1.4规定的方法之一。 4.2.1.1 压力-温度额定值方法 管道组成件的压力-温度额定值的确定应符合下列规定： a) 除本部分另有规定外，表13中已规定压力-温度额定值的管道组成件，其设计温度下的最大允许工作压力按相关标准规定的压力-温度额定值； b) 如设计温度高于表13中相关标准给出的温度额定值，但不高于GB／T 20801.2规定的材料使用温度上限者，设计者可根据相关温度下的材料许用应力折算； c) 对于表13中仅标明公称压力的管道组成件，设计温度下的最大允许工作压力可根据设计温度和常温下的材料许用应力折算； d) 表13中未列入的管道组成件，其适用的压力-温度值应符合5.3.3的规定。 4.2.1.2 压力设计方法 管道组成件的压力设计应符合下列规定： a) 直管、斜接弯头、弯管、盲板、非标法兰和非标对焊管件等管道组成件应按第6章设计； b) 对于按壁厚系列规定的承插焊管件和螺纹管件，其设计温度下的最大允许工作压力应不大于具有相同壁厚系列和相同许用应力的无缝直管按有效厚度确定的最大允许工作压力； c) 支管与主管直接连接的压力设计应符合6.7、6.8的规定。 4.2.1.3 验证性压力试验方法 管道组成件的验证性压力试验应符合下列规定： a) 对于表13中的对焊管件，如未按4.2.1.2a)进行压力设计，可进行验证性压力试验并在验证性压力试验的覆盖范同内按4.2.1.2b)确定其设计温度下的最大允许工作压力； b) 其他管道组成件也可根据验证性压力试验确定其最大允许工作压力。 4.2.1.4 其他方法 除4.2.1.1、4.2.1.2和4.2.1.3规定的方法外，管道组成件的最大允许工作压力也可以采用对比经验分析、应力分析或实验应力分析方法确定。 4.2.2 管道系统压力-温度设计准则 管道系统的压力-温度设计应符合下列规定： a) 除4.2.3的规定外，管道的设计压力应不大于该管道系统中所有管道组成件按4.2.1确定的设计温度下的最大允许工作压力的最小值； b) 不同流体工况的管道连接时，分隔阀门的额定值应按苛刻工况确定。但位于阀门任一侧的管道均应按相应的工况条件进行设计。 4.2.3 压力和温度的允许变动范围 4.2.3.1 确定设计压力和设计温度时，应考虑管道系统运行时发生的压力和温度的变动。 4.2.3.2 GC1级管道压力和温度不得超出设计范围。 4.2.3.3 除符合下列各项条件以及4.2.3.4的要求外，GC2和GC3级管道应按压力和温度变动中的最苛刻组合确定设计条件： a) 管道系统中没有铸铁或其他脆性金属材料的管道组成件； b) 由压力产生的管道名义应力不超过材料在相应温度下的屈服强度； c) 总应力符合7.5.5的规定； d) 管道系统预期寿命内，超过设计条件的压力-温度变化的总次数不大于1000次； e) 压力变动的上限值不大于管道系统的试验压力； f) 持续和周期性变动不改变管道系统中所有管道组成件的操作安全性能； g) 温度变动的下限值不小于GB／T 20801.2规定的材料最低使用温度； h) 阀门闭合元件的压力差不超过阀门制造商规定的最大额定压力差。 4.2.3.4 超过设计条件的压力偶然变动应限制在下列任一范围内： a) 压力超过相应温度下的压力额定值或由压力产生的管道名义应力超过材料许用应力值的幅度和频率应满足下列条件之一： 1) 变动幅度不大于33％，每次变动时间不超过10 h，且每年累计变动时间不超过100 h； 2) 变动幅度不大于20％，每次变动时间不超过50 h，且每年累计变动时间不超过500 h。 b) 当波动为自限(例如压力泄放)时，在每次变动时间不超过50h且每年累计变动时间不超过500h条件下，压力额定值变动幅度不大于20%，或管道名义应力超过材料许用应力值的幅度不大于20%。 4.2.4 许用应力 4.2.4.1 金属材料许用应力和螺栓材料许用应力应符合GB／T 20801.2—2020表A.1和表A.2的规定。 注：表中许用应力值未包括材料的纵向焊接接头系数φW、焊接接头高温强度降低系数W和铸件质量系数φC(见表4)。 4.2.4.2 GB／T 20801.2—2020表A.1和表A.2以外的金属材料和螺栓材料应按表1和表2规定的准则确定各自的许用应力。 4.2.4.3 拉伸许用应力按4.2.4.1和4.2.4.2取值。 4.2.4.4 压缩许用应力应符合结构稳定性的要求，且不大于拉伸许用应力。 4.2.4.5 剪切许用应力取拉伸许用应力的80%，接触许用应力取拉伸许用应力的160%。 4.2.5 纵向焊接接头系数φW 管子和对焊管件的纵向焊接接头系数φW应按表3规定的准则或GB／T 20801.2—2020表A.3确定。 表1 金属材料许用应力准则 材料 许用应力应不大于下列各值中的最小值 抗拉强度下限值 Rm／MPa 屈服强度下限值 ReL(Rp0.2)／MPa 设计温度下屈服强度 持久强度平均值或持久强度最低值 或 蠕变极限 平均值 灰铸铁 — — — — 可锻铸铁 — — — — 球墨铸铁，碳钢、合金钢、铁素体不锈钢、延伸率小于35%的奥氏体不锈钢、双相不锈钢、钛和钛合金、铝和铝合金 ， 延伸率大于或等于35%的奥氏体不锈钢和镍基合金 ， a对于法兰或其他有微量永久变形就引起泄漏或故障的场合不能采用。 表2 螺栓材料许用应力准则 材料 许用应力应不大于下列各值中的最小值 抗拉强度下限值 Rm／MPa 屈服强度下限值 ReL(Rp0.2)／MPa 设计温度下屈服强度 持久强度平均值或持久强度最低值 或 蠕变极限 平均值 非热处理或应变 强化的螺栓材料 ， 热处理或应变 强化的螺栓材料 ， 注1：对于热处理或应变强化处理的螺栓材料，许用应力取表中最小值。若该许用应力小于材料退火状态下的许用应力，取非热处理或应变强化(即退火状态)螺栓材料的许用应力。 注2：表列螺栓许用应力准则仅用于非标准法兰设计的螺栓强度要求，而螺栓安装的目标应力可达50%～70%螺栓材料的屈服强度。 表3 纵向焊接接头系数φW 序号 焊接型式 焊缝类型 检查 φW 1 连续炉焊a 直缝 按材料标准规定 0.60 2 电阻焊(ERW)a 直缝或螺旋缝 按材料标准规定 0.85 3 电熔焊(EFW) 单面对接焊(带或不带填充金属) 直缝或螺旋缝 按材料标准或本部分规定不作RT 0.80 局部(10%)RT 0.90 100%RT 1.00 双面对接焊(带或不带填充金属) 直缝或螺旋缝(除序号4外) 按材料标准或本部分规定不作RT 0.85 局部(10%)RT 0.90 100%RT 1.00 4 GB／T 9711电熔焊(EFW)，双面对接焊 直缝(一条或两条)或螺旋缝 按GB／T 9711规定 0.95 附加100%RT 1.00 a不得通过附加无损检测来提高电阻焊(ERW)的纵向焊接接头系数。 表4 铸件质量系数φC及附加无损检测要求 序号 附加无损检测要求 铸件质量系数φC 1 铸件表面加工至Ra6.3，提高目视检查的清晰度，并满足JB／T 7927—2014中B级的要求 0.85 2 铸件表面按JB／T 6902—2008(PT)中的4级或JB／T 6439(MT)进行着色渗透检测或磁粉检测 0.85 3 铸件按JB／T 6440(RT)或JB／T 6903—2008(UT)中的2级进行射线照相或超声检测 0.95 4 同序号1和序号2 0.90 5 同序号1和序号3 1.00 6 同序号2和序号3 1.00 4.2.6 铸件质量系数φC 4.2.6.1 铸铁件(灰铸铁、球墨铸铁、可锻铸铁)的铸件质量系数φC取1.0。 4.2.6.2 除铸铁外，GB／T 20801.2—2020表A.1中金属静态铸件应按JB／T 7927进行外观检查，且不低于B级要求，铸件质量系数取0.8。 4.2.6.3 对需要进行附加无损检测的铸件可取表4中的铸件质量系数，但铸件质量系数φC的改变并不影响管道组成件的压力-温度额定值。 4.2.7 焊接接头高温强度降低系数W 4.2.7.1 使用表5所列高温蠕变工况的铬钼合金钢、强韧型铁素体耐热钢、300系奥氏体不锈钢、800和600镍基合金焊接接头的长期工作强度可能低于母材。 按第6章设计承受内压的焊接直管和弯管、弯头、斜接弯头、异径管等对焊管件壁厚时，许用应力与纵向焊接接头系数的乘积SφW还应乘以焊接接头高温强度降低系数W；计算由持续性荷载产生的轴向应力时，环焊缝的许用应力Sh也应乘以W。 4.2.7.2 符合下列条件之一者，可不计焊缝接头高温强度降低系数W： a) 评价临时荷载(如风荷载、地震荷载)时； b) 按4.2.3评价的压力和温度允许变动范围时； c) 按a)或b)条件的额定压力或许用应力； d) 按7.5.5.3计算柔性分析的许用应力范围SA时。 4.2.7.3 对于表5以外的材料，除4.2.7.4以外，温度不高于510℃时，W取1.0；温度为815℃时，W取0.5，中间数值采用线性内插法计算；温度高于815℃时，由设计者确定W。 4.2.7.4 允许通过焊接接头蠕变断裂试验确定大于表5或4.2.7.3的W值，但应符合下列规定： a) 应采用全厚度包括母材、焊缝及热影响区的横向焊接接头试样； b) 持久断裂时间不低于1000 h。