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Pressure piping code - Industrial piping - Part 4: Fabrication and assembly 1 Scope This part of GB/T 20801 specifies the basic requirements for pressure piping fabrication and assembly. These basic requirements include provisions on fabrication, welding, preheating, heat treatment, assembly and erection, and piping cleaning. This part is applicable to the fabrication and assembly of pressure piping components defined in 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 985.1 Recommended joint preparation for gas welding, manual metal arc welding, gas-shield arc welding and beam welding GB/T 985.2 Recommended joint preparation for submerged arc welding GB/T 985.3 Recommended joint preparation for gas-shield arc welding on aluminium and its alloys GB/T 985.4 Recommended joint preparation for welding on clad steels GB/T 13927 Industrial valves - Pressure testing 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 20801.3-2020 Pressure piping code - Industrial piping - Part 3: Design and calculation 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 50236 Code for construction of field equipment, industrial pipe welding engineering NB/T 47014 Welding procedure qualification for pressure equipment TSG ZF001 Safety technical supervision regulations for safety valves TSG Z6002 Examination rules for welding operators of special equipment 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 20801.3-2020, GB/T 20801.5-2020, GB/T 20801.6-2020 and the following apply. 3.1 manufacture production process of products such as pipes, piping components or piping supports 3.2 fabrication preparations before the erection of pipings Note: It includes cutting, threading, grooving, forming, bending, welding and assembling assemblies into components, which may be done in workshop or on site. 3.3 assembly process of connecting two or more piping components together (including piping prefabrication) by bolts, welding, bonding, threading, brazing, soldering or sealing elements according to the design documents 3.4 erection process of completely fixing a piping system on the designated position and bracket according to the design documents Note: It includes all on-site fabrication, assembly, checking and test of the system according to the specification requirements. 3.5 isometric diagram diagram that each piping is drawn as a 3D view of piping represented by a single line according to the drawing method of axonometric projection 3.6 hot bending process of fabricating the bend when the temperature is higher than the critical point AC1 of metal 3.7 cold bending process of fabricating the bend when the temperature is lower than the critical point AC1 of metal 3.8 pipe-segments to be prefabricated pipe-segment, which is determined and can be processed in advance, selected according to the isometric diagram before the piping is fabricated and processed 3.9 pipe-segments for dimension adjustment pipe-segment, which is determined and can be processed after measuring the erection dimension, selected according to the isometric diagram before the piping is fabricated and processed 3.10 tack weld weld used to keep the weldment in position until the final weld is completed 3.11 weldment assembly made by welding all components of a member Note: The weldment includes two parts, namely base metal and welded joint. 3.12 welding procedure qualification process of preparing test piece and specimen according to the requirements of the pre-welding procedure specification and conducting test and evaluating the result in order to verify the correctness of the proposed welding procedure of weldments 3.13 welding procedure qualification report document recording relevant test data and results during welding procedure qualification 3.14 welding procedure specification document of technical details which is prepared based on the welding procedure qualification report and practical experience to directly guide welding production Note: It includes detailed regulations on welding joint, base metal, welding material, welding position, preheating, electrical characteristics and operation technology to ensure the reproducibility of welding quality. 3.15 welding performance qualification process of evaluating the operation performance of welders 3.16 preheating process of heating the base metal before or during the forming, welding or cutting process 3.17 interpass temperature instantaneous temperature of multi-pass weld and adjacent base metal before welding the next pass 3.18 post weld heat treatment thermal process that can change the structure and properties of welded joint or welding residual stress 3.19 pipework components general term for all kinds of parts and components connected or assembled into a piping system, including piping components and piping supports 3.20 final closure point the last connection port to be assembled between two fixed positions in a piping system Note: The final closure point of the piping may be connected by welding (butt joint, welded connector) or flange connection. 3.21 misalignment at the final closure point deviation of the final closure point of the piping when it is assembled without external force, which may be decomposed into the misalignment deviation values in the transverse direction (X and Y axes) and the axial direction (Z-axis). Transverse (X and Y axes) deviation value indicates the deviation degree of the center lines of the end faces of two connected pipe segments; axial (Z-axis) deviation value indicates the gap between the parallel sections at the ends of two connected pipe segments 3.22 length of assembly pipe length of assembled pipe segments in a certain direction (X, Y or Z-axis), that is, the sum of the accumulated lengths of pipe segments in other two directions (transverse or axial) extending from the closure point to both ends to the nearest two fixed positions in the piping system 4 General requirements 4.1 The piping manufacturing, fabrication and erection units shall have an administrative license meeting the requirements of relevant laws and regulations on pressure piping safety supervision. Piping fabrication and erection units shall establish corresponding quality assurance system and meet the following requirements: a) It shall have a sound quality management system and fabrication and erection process documents, and the process documents (such as construction organization design and construction scheme, etc.) shall be approved by the owner (or its entrusting party) before being used for piping fabrication or erection; b) The personnel participating in piping fabrication and erection shall have corresponding abilities and perform their respective duties; c) The metrological instruments used shall pass the verification and be used within the validity period. 4.2 The fabrication and erection of pipings shall be carried out according to the design documents and the requirements of this part. If it is necessary to modify design documents and substitute engineering materials, it shall be approved by the original design unit, and a written document shall be issued. 4.3 The piping fabrication and erection units should adopt the information management system of piping welding, and timely input and save the relevant data of pipework components, welding, heat treatment, checking, test, etc. 4.4 The piping fabrication and erection units shall establish and properly keep the necessary construction records and supporting documents. After the completion of the piping erection work, the fabrication and erection units shall submit at least the following technical documents and materials to the owner: a) As-built drawings of piping erection (including piping isometric diagram, design modification documents and material substitution sheets). Changes such as design modification and material substitution shall be marked directly on the as-built drawing. The piping isometric diagram shall at least include the material, specification and furnace batch number of piping components, actual dimensions of pipe segment, weld position, weld No., welder code, non-destructive testing method, local or sampling nondestructive testing weld position, weld repairing position, heat treatment weld position, etc. b) Product certificate, quality certificate, re-inspection report, or test report of piping components, supports and welding materials. c) Inspection records and inspection and test reports of piping fabrication and erection. Inspection records of piping fabrication and erection shall include piping welding checking records, weld repair checking records, piping concealment records, piping heat treatment curve records and reports, etc. d) Quality certificate of piping erection. If piping components or piping supports are fabricated on site, the quality certificates of piping components and piping supports shall also be submitted. 5 Inspection and acceptance of pipework components and materials 5.1 Acceptance of material marking and quality certificates The marking and quality certification documents of pipework components and materials shall be accepted in accordance with the design documents and the requirements of 9.1 and 9.2 in GB/T 20801.2-2020, and shall also meet the following requirements: a) The supplier (manufacturer) shall provide various property data or inspection results according to the requirements of design documents and supply contracts, and shall comply with those specified in the design documents and product standards; b) If the property data or inspection results provided by the quality certification documents do not meet the requirements of product standards and design documents, or if the recipient has any objection to the property data or inspection results, necessary verification tests or supplementary tests shall be conducted; c) The marking of pipework components and materials shall be clear and complete, and can be traced back to the product quality certificate. 5.2 Appearance inspection Pipework components and materials shall be checked for their materials, specifications, models and quantities according to the requirements of design documents and product standards, and their appearance quality and geometric dimensions shall be checked and accepted piece by piece. The results shall meet the requirements of design documents and corresponding product standards. 5.3 Material inspection For piping components made of Cr-Mo alloy steel, nickel-containing low-temperature steel, stainless steel, nickel and nickel alloy, titanium and titanium alloy materials, the content of main alloy elements shall be checked by positive material identification (PMI) or other methods before use, and the quantity shall meet the following requirements: a) For GC1 piping, the inspection quantity shall be 10% of each inspection lot and at least one piping component shall be randomly selected for inspection; b) For other pipings, the inspection quantity shall be 5% of each inspection lot and at least one piping component shall be randomly selected for inspection. Note: Each inspection lot indicates a batch of pipework components or materials with the same furnace batch number, the same model and specification and arrived at the same time. 5.4 Valve pressure test 5.4.1 The valves shall be subjected to pressure test, and the quantity shall meet the following requirements: a) The valves used in GC1 pipings shall be subjected to shell pressure test and sealing test piece by piece; b) For valves used in GC2 pipings, 10% of each inspection lot shall be sampled for shell pressure test and sealing test, and at least one valve shall be tested; c) For valves used in GC3 pipings, 5% of each inspection lot shall be sampled for shell pressure test and sealing test, and at least one valve shall be tested; d) With the consent of the designer or the owner, the valves that have been subjected to pressure test under witnessing piece by piece in the manufacturer and have the record of test under witnessing may be exempted from the pressure test. 5.4.2 The pressure test methods, procedures and test results of valves shall meet the requirements of design documents and supply contracts. If no requirement is specified, the requirements given in GB/T 13927 shall be met. 5.4.3 With the consent of the designer or the owner, the gate valve with nominal pressure less than or equal to PN100 and nominal diameter greater than or equal to DN600 may be subjected to the pressure test along with the piping system, and the sealing test may adopt color printing method. 5.4.4 The safety valve shall be verified according to the requirements of TSG ZF001 and design documents. 5.4.5 If jacket pressure test is carried out on valves with jackets, the test pressure shall be 1.5 times the design pressure of jackets. 5.5 Other inspections If other inspection and acceptance requirements (such as nondestructive testing, hardness inspection, etc.) are put forward for pipework components and materials in design documents, they shall be met. The inspection method, quantity and results shall meet the requirements of the design documents and relevant standards. 5.6 Disposal of rejected products 5.6.1 If one piece of pipework components and materials is rejected during sampling inspection, testing or test, the inspection lot subjected to the sampling inspection, testing or test shall be deemed as rejected, and the batch of pipework components and materials shall not be used, or the batch of pipework components and materials shall be subjected to inspection, testing or test piece by piece, and the acceptable ones may still be used. 5.6.2 During sampling inspection, testing or test of pipework components and materials, records and material identification markings shall be made, and rejected products shall be isolated. 5.7 Material storage Pipework components and materials shall be properly stored during fabrication and erection, and shall not be confused or damaged. Pipework components and materials of stainless steel and non-ferrous metals shall not contact with carbon steel and low alloy steel during storage. Pipes, valves and pipe fittings that are not erected for the time being shall be subjected to pipe orifice closure. 6 Piping fabrication 6.1 Cutting and groove processing 6.1.1 Cold cutting or thermal cutting may be adopted for cutting pipework components and materials. Where thermal cutting is adopted, the surface slag and surface layer affecting the piping welding quality shall be removed by machining or grinding. 6.1.2 Carbon steel and carbon manganese steel may be cut and its groove may be prepared by machining or flame cutting. Low-temperature nickel steel and alloy steel should be cut and its groove should be prepared by machining. 6.1.3 Stainless steel and non-ferrous metal shall be cut and its groove shall be prepared by machining or plasma cutting. If stainless steel, nickel and nickel alloy, titanium and titanium alloy, zirconium and zirconium alloy are cut or ground with grinding wheels, special grinding wheels shall be used. 6.1.4 Mechanical damage to the surface of pipework components and materials shall be avoided during processing, fabrication and erection. Repair welding or grinding shall be carried out on the positions with serious scars, and the wall thickness of the ground place shall not be less than the design wall thickness. 6.2 Marking transplantation 6.2.1 During the fabrication process of piping components, the original markings of materials shall be checked and preserved as far as possible. If the original markings cannot be preserved, the material identification shall be carried out again by transplantation, and the engineering uniform code or color marking of piping components may also be adopted for the material identification. 6.2.2 The marking method shall be based on the principle of not causing damage or pollution to materials, and hard printed markings shall not be used for low-temperature steel, stainless steel and non-ferrous metals. If austenitic stainless steel and non-ferrous metal materials are marked with color marks, the printed colors shall not contain substances that damage the materials, such as sulfur, lead and chlorine. 6.2.3 If marking methods other than hard printing or engraving are adopted, the fabricator shall ensure that there will be no confusion between different materials, such as separate treatment (time and place) or distinguishing color bands. 6.3 Bend 6.3.1 When fabricating the bend, appropriate bending process and equipment shall be adopted according to pipe material properties, working conditions of conveying fluid and bending radius of pipe. 6.3.2 Two methods can be used for bend fabrication: hot bending and cold bending. 6.3.3 If welded pipe is used for bend fabrication, the weld shall avoid the tension (compression) zone. 6.3.4 The out-of-roundness, fold and thinning of bends shall meet the following requirements: a) The out-of-roundness shall meet the following requirements: 1) The out-of-roundness u (%) of the bend shall be calculated using Formula (1): (1) where, u——the out-of-roundness of the bend; Dmax——the maximum measured outer diameter of the same section, mm; Dmin——the minimum measured outer diameter of the same section, mm; 2) For bends under internal pressure, the out-of-roundness shall not exceed 8%; for bends under external pressure, the out-of-roundness shall not exceed 3%. b) The fold height hm on the inner side of the bend shall not be greater than 3% of the pipe outer diameter D1, and the wave spacing a shall not be less than 12hm. Where, hm is the average height of two adjacent folds and shall be calculated using Figure 1 and Formula (2): (2) where, hm——the fold height, mm; D2——the outer diameter at the convex part of the fold, mm; D3——the outer diameter at the concave part of the fold, mm; D4——the outer diameter at the convex part of the adjacent fold, mm. Figure 1 Fold and wave spacing of bend c) The wall thickness of the pipe before bend fabrication should meet those specified in Table 1. The minimum thickness after bend fabrication shall not be less than the design thickness of straight pipe. Table 1 Wall thickness of pipe before bend fabrication In: mm Bending radius R Wall thickness before bend fabrication R≥6D 1.06td 5D≤R<6D 1.08td 4D≤R<5D 1.14td 3D≤R<4D 1.25td Note: D is the outer diameter of the pipe and td is the design thickness of the straight pipe. 6.3.5 After the bend of GC1 piping is bent, magnetic particle inspection or penetrant inspection shall be carried out on the bent parts piece by piece, and shall meet the requirements of GB/T 20801.5-2020. The linear defects found shall be ground, and the wall thickness after grinding shall not be less than the design thickness of the straight pipe. 6.4 Plate welded pipe 6.4.1 The fabrication of plate welded pipe shall meet the requirements of design documents and product standards. 6.4.2 The following requirements shall be met when fabricating and erecting the plate welded pipe with a nominal diameter of not less than 400 mm: a) The length of a single cylindrical section shall not be less than 300 mm, and the longitudinal welds of adjacent cylindrical sections shall be staggered by more than 100 mm. The distance from the outer wall of branch pipe to the weld should not be less than 50 mm. b) There shall be no more than two longitudinal welds on the same longitudinal weld, and the distance between longitudinal welds shall be no less than 200 mm. c) For plate welded pipe with reinforcing ring, the butt weld of reinforcing ring shall be staggered with the longitudinal weld of the pipe and not less than 100 mm, and the distance from the reinforcing ring to the girth weld of the pipe shall not be less than 50 mm. d) The perimeter and pipe end diameter of plate welded pipe shall meet those specified in Table 2. Table 2 Perimeter tolerance and diameter tolerance of plate welded pipe In: mm Nominal diameter ≤800 >800~1,200 >1,200~1,600 >1,600~2,400 >2,400~3,000 >3,000 Perimeter tolerance ±5 ±7 ±9 ±11 ±13 ±15 Diameter tolerance 4 4 6 8 9 10 Note: The diameter tolerance is the difference between the maximum and minimum outer diameters of pipe ends (within 100 mm). e) Edge angle at longitudinal weld [Figure 2a)] (measured respectively on inner wall and outer wall of pipe with sample plate with chord length equal to 1/6 Di and not less than 300 mm) and edge angle at girth weld [Figure 2b)] (checked on inner wall and outer wall of pipe with straight edge), and the E value shall not be greater than 10% of wall thickness plus 2 mm and shall not exceed 5 mm. a) Longitudinal weld b) Girth weld Figure 2 Check of edge angles at longitudinal and girth welds f) The misalignment of butt weld shall meet those specified in Table 3 and the following requirements: 1) For longitudinal and girth welds that can only be welded from one side, the misalignment of the inner wall shall not exceed 25% of the wall thickness and shall not exceed 2 mm; 2) If assembling the composite steel plate, it shall be based on the clad surface, and the misalignment shall not be greater than 50% of the clad thickness of the steel plate and not greater than 1 mm. Table 3 Butt weld misalignment of plate welded pipe In: mm Thickness of base metal T Misalignment Longitudinal weld Girth weld T≤12 ≤T/4 ≤T/4 12 g) The straightness tolerance of the plate welded pipe shall not be greater than 0.2% of its length. h) The welding, post weld heat treatment, check and inspection of plate welded pipe shall meet the requirements in relevant clauses of this part and in GB/T 20801.5-2020. i) Pressure test shall be carried out on plate welded pipes piece by piece, and the test pressure shall meet the corresponding requirements of GB/T 20801.5-2020. With the consent of the owner or designer, the pressure test method of plate welded pipe may be replaced by full radiographic or ultrasonic testing on longitudinal weld and girth weld specified in GB/T 20801.5-2020. 6.5 Mitre bend 6.5.1 Unless otherwise specified in the design, the fabrication of mitre elbows shall meet the requirements of 6.5.2 ~ 6.5.4. The welding of mitre elbows shall meet the requirements of Clause 7, and the check and inspection of miter elbows shall also meet the relevant requirements of GB/T 20801.5-2020. 6.5.2 The mitre elbow may be prepared according to the composition shown in Figure 3. For mitre elbows with a nominal diameter greater than 400 mm, the number of middle joints may be appropriately increased, but the minimum width of the inner side shall not be less than 50 mm Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 General requirements 5 Inspection and acceptance of pipework components and materials 6 Piping fabrication 7 Welding 8 Preheating 9 Heat treatment 10 Assembly and erection 11 Stainless steel, non-ferrous metal pipings 12 Piping cleaning, purging and rinse Annex A (Informative) Evaluation method of misalignment at the closure point of pipings Annex B (Informative) Bolt tightening method and target load of erection of flange joint 压力管道规范 工业管道 第4部分：制作与安装 1 范围 GB／T 20801的本部分规定了压力管道制作与安装的基本要求。这些基本要求包括制作、焊接、预热、热处理、装配和安装以及管道清理等方面的规定。 本部分适用于GB／T 20801.1范围界定的压力管道元件的制作与安装。 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 985.1 气焊、焊条电弧焊、气体保护焊和高能束焊的推荐坡口 GB／T 985.2 埋弧焊的推荐坡口 GB／T 985.3 铝及铝合金气体保护焊的推荐坡口 GB／T 985.4 复合钢的推荐坡口 GB／T 13927 工业阀门 压力试验 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 20801.3—2020 压力管道规范 工业管道 第3部分：设计和计算 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 50236 现场设备、工业管道焊接工程施工规范 NB／T 47014 承压设备焊接工艺评定 TSG ZF001 安全阀安全技术监察规程 TSG Z6002 特种设备焊接操作人员考核细则 3 术语和定义 GB／T 20801.1—2020、GB／T 20801.2—2020、GB／T 20801.3—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 制造 manufacture 管子、管道组成件或管道支承件等产品的生产过程。 3.2 制作 fabrication 管道安装前的准备工作。 注：包括切割、加工螺纹、开坡口、成型、弯曲、焊接和将组件装配成部件，可在车间或现场讲行。 3.3 装配 assembly 按照设计文件的规定，用螺栓、焊接、粘结、螺纹、硬钎焊、软钎焊或使用密封元件将两个或两个以上管道组成件连接在一起(包括管道预制)的过程。 3.4 安装 erection 根据设计文件的规定，将一个管道系统完整地固定在指定位置和支架上的过程。 注：包括按规范要求对该系统所做的所有现场制作、装配、检查和试验等工作。 3.5 轴测图 isometric diagram 按照轴测投影的绘制方法将每条管道画成以单线表示的管道空视图。 3.6 热弯 hot bending 在温度高于金属临界点AC1时制作弯管的工艺。 3.7 冷弯 cold bending 在温度低于金属临界点AC1时制作弯管的工艺。 3.8 自由管段 pipe-segments to be prefabricated 在管道制作加工前，按照轴测图选择确定的、可以先行加工的管段。 3.9 封闭管段 pipe-segments for dimension adjustment 在管道制作加工前，按照轴测图选择确定的、经实测安装尺寸后再行加工的管段。 3.10 定位焊缝 tack weld 在完成最终焊缝以前，用以保持焊接件定位的焊缝。 3.11 焊件 weldment 以焊接方法将构件各部件焊接成的组件。 注：焊件包括母材和焊接接头两部分。 3.12 焊接工艺评定 welding procedure qualification 为验证所拟定的焊件焊接工艺的正确性，按照预焊接工艺规程的规定，制备试件和试样，并进行试验及结果评价的过程。 3.13 焊接工艺评定报告 welding procedure qualification report 记录焊接工艺评定过程中有关试验数据及结果的文件。 3.14 焊接工艺规程 welding procedure specification 根据焊接工艺评定报告，并结合实践经验而制定的直接指导焊接生产的技术细则文件。 注：包括对焊接头、母材、焊接材料、焊接位置、预热、电特性、操作技术等内容进行详细的规定，以保证焊接质量的再现性。 3.15 焊接技能评定 welding performance qualification 对焊接作业人员的操作技能进行评估考核的过程。 3.16 预热 preheating 在成型、焊接或切割过程之前或之间对母材进行加热的过程。 3.17 道间温度 interpass temperature 多道焊缝及相邻母材在施焊下一焊道之前的瞬时温度。 3.18 焊后热处理 post weld heat treatment 能改变焊接接头的组织和性能或焊接残余应力的热过程。 3.19 管道元件 pipework components 连接或装配成管道系统的各种零部件的总称，包括管道组成件和管道支承件。 3.20 最终封闭口 final closure point 在管道系统中两个固定位置之间进行装配的最后一个连接口。 注：管道最终封闭口的连接方式可为焊接(对接接头、承插焊接头)或法兰连接。 3.21 最终封闭口错口偏差 misalignment at the final closure point 管道最终封闭口在不受外力状态下装配时的偏差，可分解为横向(X、Y轴)和轴向(Z轴)三个方向的错口偏差值。横向(X、Y轴)偏差值表示两个被连接管段的端面中心线的偏离程度；轴向(Z轴)偏差值表示两个被连接管段端部平行截面之间的间隙量。 3.22 装配管道长度 length of assembly pipe 某方向(X、Y或Z轴)上的装配管段长度，即管道系统中从封闭点向两端延伸到最近的两个固定位置之间的其他两个方向(横向或轴向)上的管段累积长度之和。 4 一般规定 4.1 管道的制造、制作和安装单位应具有符合压力管道安全监察有关法规要求的行政许可证。管道制作和安装单位应建立相应的质量保证体系，并符合下列规定： a) 具有健全的质量管理制度以及制作、安装工艺文件，工艺文件(如施工组织设计、施工方案等)应经业主(或其委托方)批准后方可用于管道制作或安装工作； b) 参加管道制作或安装的人员应具备相应的能力并履行各自的职责； c) 使用的计量器具应检定合格并在有效期内。 4.2 管道的制作和安装应按设计文件及本部分的规定进行。当需要修改设计文件及工程材料代用时，应经原设计单位同意，并出具书面文件。 4.3 管道的制作和安装单位宜采用管道焊接信息化管理系统，及时输入并保存管道元件、焊接、热处理、检查与试验等相关数据。 4.4 管道的制作和安装单位应建立并妥善保存必要的施工记录及证明文件。管道安装工程竣工后，制作和安装单位应向业主至少提交以下技术文件和资料： a) 管道安装竣工图(含管道轴测图、设计修改文件和材料代用单)。设计修改和材料代用等变更内容应在竣工图上直接标注。管道轴测图应至少包括管道组成件的材质、规格和炉批号、管段的实际尺寸、焊缝位置、焊缝编号、焊工代号、无损检测方法、局部或抽样无损检测焊缝的位置、焊缝补焊位置、热处理焊缝位置等。 b) 管道组成件、支承件和焊接材料的产品合格证、质量证明书或复验、试验报告。 c) 管道制作、安装检查记录和检验、试验报告。管道制作、安装检查记录应包含管道焊接检查记录、焊缝返修检查记录、管道隐蔽记录、管道热处理曲线记录及报告等内容。 d) 管道安装质量证明书。如果现场制作管道组成件或管道支承件，还应提交管道组成件和管道支承件的质量证明书。 5 管道元件及材料的检查与验收 5.1 材料标记和质量证明文件的验收 管道元件及材料的标记和质量证明文件除应按设计文件以及GB／T 20801.2—2020中9.1和9.2的规定进行验收外，还应满足以下要求： a) 供货方(制造商)应按设计文件和供货合同的规定提供各项性能数据或检验结果，且应符合设计文件和产品标准的规定； b) 质量证明文件提供的性能数据或检验结果如不符合产品标准和设计文件的规定，或者接受方对其性能数据或检验结果有异议时，应进行必要的验证性试验或补充试验； c) 管道元件及材料的标记应清晰完整，并能够追溯到产品质量证明文件。 5.2 外观检查 管道元件及材料应按设计文件和产品标准的规定核对其材质、规格、型号和数量，并逐个进行外观质量和几何尺寸的检查验收，其结果应符合设计文件和相应产品标准的规定。 5.3 材质检查 对于铬钼合金钢、含镍低温钢、不锈钢以及镍及镍合金、钛及钛合金材料的管道组成件，在使用前应采用光谱分析(PMI)或其他方法对主要合金元素含量进行检查，其数量应满足以下要求： a) 对于GC1级管道，检查数量应按每个检验批的10％且不少于1个管道组成件进行抽查； b) 其他管道为每个检验批抽查5％，且不少于1个管道组成件。 注：每个检验批表示同炉批号、同型号规格、同时到货的一批管道元件或材料。 5.4 阀门压力试验 5.4.1 阀门应进行压力试验，其数量应满足以下要求： a) 用于GC1级管道的阀门，应逐个进行壳体压力试验和密封试验； b) 用于GC2级管道的阀门，应按每个检验批抽查10％进行壳体压力试验和密封试验，且不得少于1个； c) 用于GC3级管道的阀门，应按每个检验批抽查5％进行壳体压力试验和密封试验，且不得少于1个； d) 经设计者或业主同意，到制造厂逐件见证压力试验并有见证试验记录的阀门，可免除压力试验。 5.4.2 阀门的压力试验方法、程序与试验结果应符合设计文件和供货合同的规定。当无规定时，应符合GB／T 13927的规定。 5.4.3 经设计者或业主同意，对于公称压力小于或等于PN100且公称直径大于或等于DN600的闸阀，可随管道系统进行压力试验，密封试验可采用色印方法。 5.4.4 安全阀的校验应按TSG ZF001和设计文件的规定进行。 5.4.5 带夹套的阀门进行夹套压力试验时，其试验压力应为1.5倍的夹套设计压力。 5.5 其他检查 当设计文件对管道元件和材料提出其他检查与验收要求(如无损检测、硬度检查等)时，应予以满足。检查方法、数量及检查结果应符合设计文件和相关标准的规定。 5.6 不合格品的处置 5.6.1 管道元件及材料进行抽样检查、检测或试验时，若有1件不合格，则该抽样检查、检测或试验所代表的这一检验批应视为不合格，该批管道元件及材料不得使用，或对该批管道元件及材料逐个进行检查、检测或试验，其中的合格者仍可使用。 5.6.2 管道元件及材料进行抽样检查、检测或试验时，应做好记录和材料识别标记，并对不合格品进行隔离处理。 5.7 材料保管 管道元件及材料在制作、安装过程中应妥善保管，不得混淆或损坏。不锈钢和有色金属的管道元件及材料在储存期间不得与碳钢、低合金钢接触。暂不安装的管子、阀门和管件，应封闭管口。 6 管道制作 6.1 切割与坡口加工 6.1.1 管道元件及材料的切割加工可采用冷切割或热切割方法。如采用热切割方法，切割后应采用机械加工或打磨方法清除表面熔渣和影响管道焊接质量的表面层。 6.1.2 碳钢、碳锰钢可采用机械加工方法或火焰切割方法切割和制备坡口。低温镍钢和合金钢宜采用机械加工方法切割和制备坡口。 6.1.3 不锈钢、有色金属应采用机械加工或等离子切割方法切割和制备坡口。不锈钢、镍及镍合金、钛及钛合金、锆及锆合金采用砂轮切割或修磨时，应使用专用砂轮片。 6.1.4 管道元件及材料在加工制作、安装过程中应避免材料表面的机械损伤。对有严重伤痕的部位应进行补焊或修磨，修磨处的壁厚应不小于设计壁厚。 6.2 标记移植 6.2.1 管道组成件在制作过程中，应核对并尽量保存材料的原始标记。当无法保存原始标记时，应采用移植方法重新进行材料标识，材料标识也可采用管道组成件的工程统一编码或色标。 6.2.2 标记方法的采用应以对材料不构成损害或污染为原则，低温用钢、不锈钢及有色金属不得使用硬印标记。当奥氏体不锈钢和有色金属材料采用色码标记时，印色不应含有对材料构成损害的物质，如硫、铅和氯等。 6.2.3 如采用硬印或雕刻之外的其他标记方法，制作者应保证不同材料之间不会产生混淆，如采用分别处理(时间、地点)或区分色带等方法。 6.3 弯管 6.3.1 制作弯管时，应根据管子材料性能、输送流体工况和管子弯曲半径，采用适当的弯曲工艺和装备。 6.3.2 制作弯管可采用热弯和冷弯两种方法。 6.3.3 当采用焊管制作弯管时，焊缝应避开受拉(压)区。 6.3.4 弯管的不圆度、褶皱和减薄应满足以下要求： a) 不圆度应满足以下要求： 1) 弯管的不圆度u(％)应按式(1)计算： (1) 式中： u——弯管的不圆度； Dmax——同一截面的最大实测外径，单位为毫米(mm)； Dmin——同一截面的最小实测外径，单位为毫米(mm)。 2) 对于承受内压的弯管，其不圆度应不大于8％；对于承受外压的弯管，其不圆度应不大于3％。 b) 弯管内侧褶皱高度hm应不大于管子外径D1的3％，且波浪间距a应不小于12hm。其中，hm为相邻两个褶皱的平均高度，并按图1和式(2)计算： (2) 式中： hm——褶皱高度，单位为毫米(mm)； D2——褶皱凸出处外径，单位为毫米(mm)； D3——褶皱凹进处外径，单位为毫米(mm)； D4——相邻褶皱凸出处外径，单位为毫米(mm)。 图1 弯管的褶皱和波浪间距 c) 弯管制作前的管子壁厚宜符合表1的规定。弯管制作后的最小厚度不得小于直管的设计厚度。 表1 弯管制作前的管子壁厚 单位为毫米 弯曲半径R 弯管制作前壁厚 注：D为管子外径，td为直管的设计厚度。 6.3.5 GC1级管道的弯管弯制后，应逐件对弯曲部位进行磁粉检测或渗透检测，且应符合GB／T 20801.5—2020的规定。发现的线性缺陷应予以修磨，修磨后的壁厚不得小于直管的设计厚度。 6.4 板焊管 6.4.1 板焊管的制作应符合设计文件和产品标准的规定。 6.4.2 制作和安装公称直径不小于400 mm的板焊管时，应符合以下规定： a) 单个筒节的长度应不小于300 mm，相邻筒节纵缝应错开100 mm以上。支管外壁距焊缝不宜小于50 mm。 b) 同一筒节上的纵向焊缝应不大于两条，纵缝间距应不小于200 mm。 c) 对于有加固环的板焊管，加固环的对接焊缝应与管子纵向焊缝错开，其间距应不小于100 mm，加固环距管子的环焊缝应不小于50 mm。 d) 板焊管的周长及管端直径应符合表2的规定。 表2 板焊管的周长允差及直径允差 单位为毫米 公称直径 ≤800 ＞800～1 200 ＞1 200～1 600 ＞1 600～2 400 ＞2 400～3 000 ＞3 000 周长允差 ±5 ±7 ±9 ±11 ±13 ±15 直径允差 4 4 6 8 9 10 注：直径允差为管端(100 mm以内)最大外径与最小外径之差。 e) 纵向焊缝处的棱角度[图2a)](用弦长等于1／6Di且不小于300 mm的样板分别在管内壁和外壁测量)和环向焊缝处的棱角度[图2b)](在管内壁和外壁用直尺检查)，其E值应不大于壁厚的10％加2 mm，且不大于5 mm。 1/6Di且不小于300 mm 样板 a) 纵向焊缝 b) 环向焊缝 图2 纵向与环向焊缝处的棱角度检查 f) 对接焊缝的错边量应符合表3及下列规定： 1) 只能从单面焊接的纵向和环向焊缝，其内壁错边量不应大于壁厚的25％，且不应超过2 mm； 2) 复合钢板组对时，应以复层表面为基准，错边量不应大于钢板复层厚度的50％，且不大于1 mm。 表3 板焊管对接焊缝的错边量 单位为毫米 母材厚度T 错边量 纵向焊缝 环向焊缝 ≤T/16，且≤10 ≤T/8，且≤20 g) 板焊管的直度允差应不大于其单根长度的0.2％。 h) 板焊管的焊接、焊后热处理和检查、检验应符合本部分相应章条及GB／T 20801.5—2020的相关规定。 i) 板焊管应逐根进行压力试验，试验压力应符合GB／T 20801.5—2020的相应规定。经业主或设计者同意，可采用GB／T 20801.5—2020规定的用纵向焊缝、环向焊缝100％射线照相或100％超声检测代替板焊管的压力试验的方法。 6.5 斜接弯头 6.5.1 除设计另有规定外，斜接弯头的制作应符合6.5.2～6.5.4的规定。斜接弯头的焊接应符合第7章的规定，斜接弯头的检查和检验还应符合GB／T 20801.5—2020的相关规定。 6.5.2 可按图3所示的组成形式配制斜接弯头。对于公称直径大于400 mm的斜接弯头，可适当增加中节数量，但其内侧的最小宽度应不小于50 mm。 6.5.3 斜接弯头的焊接接头应采用全焊透形式。公称直径大于或等于600 mm的斜接弯头宜进行双面焊。 6.5.4 公称直径大于1 000 mm时，斜接弯头的周长允许偏差应为±6 mm；公称直径小于或等于1 000 mm时，斜接弯头的周长允许偏差应为±4 mm。 a) 90°斜接弯头 b) 60°斜接弯头 c) 45°斜接弯头 d) 30°斜接弯头 图3 斜接弯头的组成形式 6.6 翻边接头 6.6.1 翻边接头宜采用符合相关标准的管件制造产品。翻边接头的制作应符合GB／T 20801.3—2020中5.1.6和本部分6.6.2、6.6.3的规定。 6.6.2 焊制翻边接头的基本形式应符合图4的规定。焊接后应对翻边部位进行机械加工或整形。密封面的表面粗糙度应符合法兰标准的规定。外侧焊缝应进行修磨，以不影响松套法兰内缘与翻边的装配为原则。 6.6.3 扩口翻边后的外径及转角半径应能保证螺栓及法兰的装配。翻边端面与管子中心线应垂直，垂直度允差应不大于1 mm。 半径 图4 典型的焊制翻边接头 6.7 夹套管 6.7.1 夹套管及其部件的结构形式与制作应符合设计文件和相关标准的规定。 6.7.2 夹套管制作过程中应确保内管的焊缝裸露可见，在内管检验合格前不得进行外管封闭焊接。 6.7.3 夹套弯管的外管组焊，应在内管制作完毕并经检验合格后进行。夹套弯管的外管和内管的同轴度偏差不得大于3 mm。 6.7.4 外管与内管间的间隙应均匀，并应按设计文件的规定安装定位板。定位板的安装应不妨碍夹套内介质流动和内管与外管的胀缩，其材质应与内管相同。定位板的几何尺寸、安装位置、间距等应符合设计文件和相关标准的规定。 6.7.5 夹套管的焊接、热处理、检查、检验与试验应符合本部分相应章条及GB／T 20801.5—2020的相关规定。 6.8 支吊架 6.8.1 管道支吊架的形式、材质、加工尺寸及精度应符合设计文件、相关标准和产品技术文件的规定。 6.8.2 管道支吊架的组装尺寸与焊接方式应符合设计文件的规定。制作后应对焊缝进行目视检查，焊接变形应予以矫正。所有螺纹连接均应按设计要求予以锁紧。 6.8.3 支吊架中要求全焊透的焊缝应进行射线检测或超声检测，且应符合GB／T 20801.5—2020的相关规定。检测数量不少于20％，且焊缝长度不小于200 mm。 6.8.4 制作合格的支吊架应进行防锈处理并应妥善分类保管。合金钢支吊架应有材质标记。 7 焊接 7.1 焊接工艺评定和焊工技能评定 7.1.1 管道承压件与承压件的焊接，承压件与非承压件的焊接，均应采用经评定合格的焊接工艺，并由合格焊工施焊。 7.1.2 焊接工艺评定应符合NB／T 47014的规定。冲击试验要求应符合GB／T 20801.2—2020中8.2的规定。 7.1.3 当焊接工艺评定要求使用的材料无法满足7.1.2的规定时，经设计者和业主同意，允许采用对预焊接工艺规程进行技术评审的方式代替焊接工艺评定，但应同时符合下列条件： a) 施焊单位已掌握该金属材料的特性(化学成分、力学性能和焊接性能)； b) 施焊单位能够提供同类别(同组别)其他母材的焊接工艺评定，且具有其施焊经验(业绩)； c) 施焊的焊工已取得相应的技能评定合格资格； d) 能够提供其他单位完成的符合7.1.2要求的该材料焊接工艺评定。 7.1.4 管道施焊前，应根据焊接工艺评定报告(或已通过技术评审的预焊接工艺规程)编制焊接工艺规程，用于指导焊工施焊和焊后热处理工作。焊接工艺规程应至少包括下列内容： a) 焊接方法及操作类型(手工、自动、半自动)； b) 焊接接头的坡口形式、尺寸及加工要求； c) 焊接接头母材的标准号、型号、规格尺寸及相关要求； d) 焊接材料的标准号、型号、牌号、规格、烘烤要求； e) 焊接位置及焊接方向； f) 预热及道间温度控制要求(预热温度、道间温度范围、加热方式及范围、测量方法等)，必要时的后热要求(后热温度、时间、加热及缓冷方式等)； g) 焊后热处理要求(热处理温度、保温时间、升温速度、降温速度、加热及测量方式等)； h) 保护气体的种类(成分)、混合配比(纯度)、流量等要求； i) 焊接电特性及焊接工艺参数； j) 焊接操作要领与技术措施； k) 其他相关要求。 7.1.5 焊工技能评定应符合TSG Z6002的规定。 7.2 焊接材料 7.2.1 焊接材料应符合设计文件和相关标准的规定，且通过焊接工艺评定验证。当设计无规定时，焊接材料的选用应按照母材的化学成分、力学性能、焊接性能、焊前预热、焊后热处理、使用条件及现场施工条件等因素综合确定，且符合下列规定： a) 焊缝金属的抗拉强度应不小于母材规定抗拉强度的下限值。对于两种不同强度的母材相互焊接，焊缝金属的抗拉强度应不低于规定抗拉强度较低母材的下限值。 b) 焊缝金属的化学成分应与母材相近。对于两种不同化学成分的母材相互焊接，除奥氏体钢与铁素体钢相互焊接外，焊缝金属的化学成分应与其中任何一个母材一致或介于两者之间。 c) 当奥氏体钢与铁素体钢相互焊接时，焊缝金属应有显著的奥氏体晶体结构，可选用25Cr-13Ni型或含镍量更高的焊接材料。当设计温度高于425℃时，宜选用镍基焊接材料。 d) 焊接材料的焊接工艺性能应良好。 7.2.2 焊接材料(包括焊条、焊丝、焊剂及焊接用气体)使用前应按设计文件和相关标准的规定进行检查和验收，且应具有质量证明文件和包装标记。 7.2.3 焊接材料(包括焊条、焊丝及焊剂)的储存应保持适宜的温度及湿度，相对湿度应不超过60％。焊接材料库应保持干燥、清洁。 7.2.4 库存期超过规定期限的焊条、焊剂及药芯焊丝，应经复验合格后方可使用。焊接材料库存的规定期限应在焊接材料质量证明书或说明书上注明。 7.2.5 应按焊接材料说明书的要求对焊条、焊剂和药芯焊丝进行烘干，焊丝使用前应按规定进行除油、除锈及清洗处理。 7.2.6 使用过程中应注意保持焊接材料的识别标记，以免错用。 7.3 焊接环境 7.3.1 焊接环境温度应能保证焊件的焊接温度和焊工技能不受影响。环境温度低于0℃时，应符合8.2.1的规定。 7.3.2 应采取防风措施保证焊接时的风速不大于以下规定值： a) 对于焊条电弧焊、自保护药芯焊丝电弧焊和气焊，规定风速为8 m／s； b) 对于钨极惰性气体保护电弧焊和熔化极气体保护焊，规定风速为2 m／s。 7.3.3 焊接电弧周围1 m范围内的相对湿度应符合以下规定： a) 铝及铝合金的焊接，相对湿度应不大于80％； b) 其他材料的焊接，相对湿度应不大于90％。 7.3.4 在雨雪天气施焊时，应采取有效防护措施，否则禁止施焊。 7.4 焊前准备 7.4.1 坡口制备 7.4.1.1 坡口加工应符合6.1的规定。坡口表面应光滑并呈金属光泽，热切割产生的熔渣和影响焊接质量的表面层应清除干净。 7.4.1.2 坡口形式和尺寸应符合设计文件的规定。无规定时，可按照GB／T 985.1、GB／T 985.2、GB／T 985.3、GB／T 985.4、GB 50236或相关标准，并结合现场实际情况确定坡口形式和尺寸。 7.4.1.3 当设计文件和相关标准对坡口表面提出无损检测的要求时，无损检测及缺陷处理应在施焊前完成。 7.4.2 清理 7.4.2.1 对于焊件坡口及内外表面，应在焊接前去除油漆、油污、锈斑、熔渣、氧化皮以及有害的其他物质。 7.4.2.2 焊件坡口及内外表面的清理应满足表4的要求。 表4 焊件坡口及其内外表面的清理 材料 清理范围／mm 清理对象 清理方法 碳素钢、低温钢、合金钢、不锈钢 ≥20 油、漆、锈、毛刺等污物，裂纹，夹层 手工或机械等方法 铝及铝合金、钛及钛合金、镍及镍合金、锆及锆合金 ≥50 油污、氧化膜等 有机溶剂除油污，化学或机械方法除氧化膜 铜及铜合金 ≥20 7.4.3 组对 7.4.3.1 对接接头的组对应符合以下规定： a) 对接接头的组对应内壁齐平，内壁错边量应符合设计文件和表5的规定； 表5 管道组对内壁错边量 材料 内壁错边量 碳素钢、低温钢、合金钢、不锈钢 不大于壁厚的10％，且小于或等于2 mm 铝及铝合金 壁厚小于或等于5 mm ≤0.5 mm 壁厚大于5 mm 不大于壁厚的10％，且小于或等于2 mm 铜及铜合金、钛及钛合金、镍及镍合金、锆及锆合金 不大于壁厚的10％，且小于或等于1 mm b) 不等壁厚的工件组对时，薄件端面的内侧和外侧应位于厚件端面范围之内。当内壁错边量不符合表5的规定或外壁错边量大于3 mm时，焊件端部应按图5的规定进行削薄修整。端部削薄修整后的壁厚应不小于设计厚度td。 注1：用于管件时，如受长度限制，图5a)、图5d)、图5f)中的15°可改为30° 注2：图5a)、图5b)和图5c)为外侧齐平，图5d)和图5e)为内侧齐平，图5f)为内外侧均不齐平。 图5 不等壁厚对接焊件的端部加工 7.4.3.2 支管连接接头的组对应符合以下规定： a) 安放式支管的端部制备及组对应符合图6a)、图6b)的规定； b) 插入式支管的主管端部制备及组对应符合图6c)的规定； c) 主管开孔与支管组对时的错边量应不大于m值[见图6a)、图6b)]，必要时可进行堆焊修正。 7.4.3.3 组对间隙应控制在焊接工艺规程允许的范围内。 7.4.3.4 除设计文件规定的管道预拉伸或预压缩焊口外，不得强行组对。需预拉伸或预压缩的焊接接头，组对时所使用的工卡具应在整个焊接及热处理完毕并经检验合格后拆除。 7.4.3.5 组对时应垫置牢固，并应采取措施防止在焊接和热处理过程中产生附加应力和变形。 a) 安放式支管(支管内径大于主管开孔直径) b) 安放式支管(支管内径小于主管开孔直径) c) 插入式支管 注1：g为根部间隙。 注2：m为错边量，其值不大于3.2 mm或 (取较小者)，其中 为支管名义厚度。 图6 支管连接接头的组对 7.4.4 定位焊缝 7.4.4.1 定位焊缝的焊接应采用与根部焊道相同的焊接材料和焊接工艺，并应由评定合格的焊工施焊。 7.4.4.2 定位焊缝应具有足够的长度、厚度和间距，以保证该焊缝在焊接过程中不致开裂。 7.4.4.3 根部焊接前，应对定位焊缝进行检查。如发现缺陷，处理后方可施焊。 7.4.4.4 焊接的工卡具材质宜与母材相同或为NB／T 47014规定的同一类别号。拆除工卡具时不应损伤母材，拆除后应确认无裂纹并将残留焊疤打磨修整至与母材表面齐平。对于下列管道，应对工卡具拆除部位进行表面无损检测： a) 铬钼合金钢管道； b) 标准抗拉强度下限值大于或等于540 MPa的合金钢管道。 7.4.5 焊接设备 焊接设备及辅助装备等应能保证焊接工作的正常进行和安全可靠，仪表应定期校验。 7.5 焊接的基本要求 7.5.1 应采用经评定合格的焊接工艺，由合格焊工按焊接工艺规程对焊缝(包括为组对而堆焊的焊缝金属)进行焊接。 7.5.2 焊接时应采取合理的焊接方法和施焊顺序： a) 碳素钢和合金钢焊接时，可采用焊条电弧焊、钨极惰性气体保护电弧焊、熔化极气体保护电弧焊、自保护药芯焊丝电弧焊、埋弧焊或气焊方法； b) 铝及铝合金焊接时，可采用钨极惰性气体保护电弧焊或熔化极惰性气体保护电弧焊方法； c) 铜及铜合金、钛及钛合金、锆及锆合金可采用钨极惰性气体保护电弧焊方法，黄铜也可采用氧乙炔焊(气焊)方法； d) 镍及镍合金可采用焊条电弧焊、钨极惰性气体保护电弧焊、熔化极惰性气体保护电弧焊或埋弧焊方法。 7.5.3 对含铬量大于或等于3％或合金元素总含量大于5％的管道焊缝，采用钨极惰性气体保护电弧焊或熔化极气体保护电弧焊进行根部焊道单面焊接时，焊缝背面应充氩气或其他保护气体，或应采取其他防止背面焊缝金属被氧化的措施。 7.5.4 除因工艺或检验要求需要分次焊接外，每条焊缝一般应一次连续焊接完成，当因故中断焊接时，应根据工艺要求采取保温缓冷或后热等措施以防止裂纹的产生。再次焊接前应检查焊层表面，确认无裂纹后，按原工艺要求继续施焊。 7.5.5 在根部焊道和盖面焊道上不宜采用锤击消除残余应力。 7.5.6 对焊接连接的阀门施焊时，所采用的焊接顺序、工艺以及焊后热处理，均应保证阀座的密封性能不受影响。 7.5.7 不得在焊件表面引弧或试验电流。对于设计温度不高于－20℃的管道、淬硬倾向较大的合金钢管道、不锈钢及有色金属管道，其表面均不得有电弧擦伤等缺陷。 7.5.8 当有下列情况之一时，管道的单面焊焊缝根部应采用钨极惰性气体保护电弧焊或能保证根部焊接质量的其他焊接工艺方法： a) GC1级管道； b) 公称直径小于500 mm，且设计温度低于－20℃的管道； c) 内部清洁要求较高且焊接后不易清理的管道； d) 机器入口管道； e) 设计规定的其他管道。 7.5.9 公称直径大于或等于500 mm的管道，宜在内侧进行根部双面焊。 7.5.10 多道焊每道焊完后，应立即进行清理和目视检查。如发现缺陷，应消除后方可进行下一层施焊。 7.5.11 规定进行层间无损检测的焊缝，无损检测应在目视检查合格后进行，表面无损检测应在射线照相检测及超声波检测前进行，经检测的焊缝在评定合格后方可继续进行焊接。 7.5.12 焊接完毕后，应及时将焊缝表面的熔渣及附近的飞溅物清理干净。 7.5.13 每个焊工均应有指定的识别代号。除工程另有规定外，管道承压焊缝应标有焊工识别标记，标记方法应符合6.2.2的规定。如无法直接在管道承压件上作焊工标记，则应在管道轴测图上或用简图记录焊工识别代号，并将简图列入交工技术文件。 7.6 焊缝设置 管道(夹套管除外)焊缝的设置应避开应力集中区，且应符合以下规定： a) 当公称直径大于或等于150 mm时，直管段上两对接环焊缝中心面之间的距离应不小于150 mm；当公称直径小于150 mm时，该距离应不小于管子外径，且不小于50 mm。 b) 管道环焊缝距离弯管(不包括弯头)起弯点的距离应不小于100 mm。 c) 管道环焊缝与支吊架的净距离应不小于50 mm。需要热处理的焊缝与支吊架的距离应不小于焊缝宽度的5倍，且应不小于100 mm。 d) 不宜在焊缝及其边缘上开孔。当无法避免在焊缝上开孔或开孔补强时，应对以开孔中心为中心、在1.5倍开孔直径或补强板直径范围内的焊缝进行无损检测，检测合格后方可进行开孔。补强板覆盖的焊缝应磨平。管孔边缘不应存在焊接缺陷。 e) 管道环焊缝距离支管或管接头的开孔边缘应不小于50 mm，且应不小于孔径。 f) 焊接管及焊接管件组对时，应尽量避免十字焊缝。当无法避免十字焊缝或焊缝的错开距离小于100 mm时，该部位焊缝应经射线检测或超声检测合格。 7.7 角焊缝 7.7.1 角焊缝(包括承插焊缝)可采用凹形和凸形，其焊缝尺寸应符合图7的规定。 7.7.2 平焊法兰或承插焊法兰的角焊缝应符合图8的规定，其他承插焊接头的最小焊缝尺寸应符合图9的规定。 |
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| GB/T 20801.4-2020, GB 20801.4-2020, GBT 20801.4-2020, GB/T20801.4-2020, GB/T 20801.4, GB/T20801.4, GB20801.4-2020, GB 20801.4, GB20801.4, GBT20801.4-2020, GBT 20801.4, GBT20801.4 |