GB/T 20801.4-2020 PDF EnglishUS$645.00 · In stock · Download in 9 seconds
GB/T 20801.4-2020: Pressure piping code - Industrial piping - Part 4: Fabrication and assembly Delivery: 9 seconds. True-PDF full-copy in English & invoice will be downloaded + auto-delivered via email. See step-by-step procedure Status: Valid GB/T 20801.4: Historical versions
Similar standardsGB/T 20801.4-2020: Pressure piping code - Industrial piping - Part 4: Fabrication and assembly---This is an excerpt. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.), auto-downloaded/delivered in 9 seconds, can be purchased online: https://www.ChineseStandard.net/PDF.aspx/GBT20801.4-2020GB NATIONAL STANDARD OF THE PEOPLE’S REPUBLIC OF CHINA ICS 23.040 J 74 Replacing GB/T 20801.4-2006 Pressure Piping Code - Industrial Piping - Part 4. Fabrication and Assembly Issued on. NOVEMBER 19, 2020 Implemented on. JUNE 1, 2021 Issued by. State Administration for Market Regulation; Standardization Administration of the People’s Republic of China. Table of ContentsForeword... 3 1 Scope... 5 2 Normative References... 5 3 Terms and Definitions... 6 4 General Rules... 9 5 Inspection and Acceptance Inspection of Pipework Components and Materials... 10 6 Fabrication of Piping... 13 7 Welding... 20 8 Preheating... 36 9 Heat Treatment... 39 10 Assembly and Erection... 49 11 Stainless Steel and Non-ferrous Metal Piping... 58 12 Piping Cleaning, Purging and Rinsing... 60 Appendix A (Informative) Evaluation Method for Misalignment of Piping at Closure Point... 63 Appendix B (Informative) Flange Joint Bolt Tightening Method and Erection Target Load... 711 ScopeThis Part of GB/T 20801 specifies the basic requirements for the fabrication and assembly of pressure piping. These basic requirements include regulations on fabrication, welding, preheating, heat treatment, assembly, erection and piping cleaning, etc. This Part is applicable to the fabrication and assembly of pressure pipework components defined in the scope of GB/T 20801.1.2 Normative ReferencesThe following documents are indispensable to the application of this document. In terms of references with a specified date, only versions with a specified date are applicable to this document. In terms of references without a specified date, the latest version (including all the modifications) is applicable to this document. 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 Aluminum 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 Regulation for Safety Valves TSG Z6002 Examination Rules for Welding Operators of Special Equipment3 Terms and DefinitionsWhat is defined in GB/T 20801.1-2020, GB/T 20801.2-2020, GB/T 20801.3-2020, GB/T 20801.5-2020 and GB/T 50801.6-2020, and the following terms and definitions are applicable to this document. 3.1 Manufacture Manufacture refers to the manufacturing process of pipes, piping components or pipe- supporting elements, etc. 3.2 Fabrication Fabrication refers to the preparation work before piping erection. 3.3 Assembly Assembly refers to the process of connecting two or more piping components (including piping pre-fabrication) with bolts, welding, bonding, threading, brazing, soldering or using sealing elements in accordance with the provisions of the design documents. 3.4 Erection Erection refers to the process of completely fixing a piping system on a designated position and support in accordance with the provisions of the design documents. 3.5 Isometric Diagram Isometric diagram refers to the drawing of each piping into an isometric drawing of piping represented by single lines in accordance with the drawing method of axonometric projection. 3.6 Hot Bending Hot bending refers to the process of fabricating bent pipes when the temperature is higher than the metal critical point AC1.4 General Rules4.1 The organization manufacturing, fabricating and erecting the piping shall have an administrative license that complies with the requirements of relevant laws and regulations for pressure piping safety supervision. The organization fabricating and erecting the piping shall establish a corresponding quality assurance system and comply with the following stipulations. 4.2 The fabrication and erection of the piping shall be carried out in accordance with the design documents and the stipulations of this Part. When it is necessary to modify the design documents and substitute engineering materials, it shall be approved by the original design organization, and a written document shall also be issued. 4.3 The organization fabricating and erecting the piping should adopt a piping welding information management system, and timely input and save the relevant data of pipework components, welding, heat treatment, inspection and testing, etc.5 Inspection and Acceptance Inspection of PipeworkComponents and Materials 5.1 Material Marking and Acceptance of Quality Certification Documents The marking and quality certification documents of pipework components and materials shall receive the acceptance inspection in accordance with the design documents and the stipulations of 9.1 and 9.2 in GB/T 20801.2-2020.In addition, they shall also satisfy the following requirements. 5.2 Appearance Inspection The pipework components and materials shall be checked for their materials, specifications, models and quantities in accordance with the stipulations of the design documents and product standards. In addition, the inspection and acceptance inspection of appearance quality and geometric dimensions shall be carried out one by one. The results shall comply with the stipulations of the design documents and the corresponding product standards. 5.3 Material Inspection For piping components made of chromium-molybdenum alloy steel, nickel-containing low-temperature steel, stainless steel, nickel and nickel alloy, titanium and titanium alloy materials, before use, positive material identification (PMI) or other methods shall be adopted to check the contents of main alloy elements. The quantity shall satisfy the following requirements. 5.4 Valve Pressure Test 5.5 Other Inspections When the design documents put forward other inspection and acceptance inspection requirements (such as. non-destructive testing and hardness inspection, etc.) for the pipework components and materials, they shall be satisfied. The inspection methods, quantities and inspection results shall comply with the stipulations of the design documents and the relevant standards. 5.6 Disposal of Non-Conforming Products 5.7 Material Storage During the fabrication and erection process, the pipework components and materials shall be properly kept, and shall not be mixed or damaged. During the storage, stainless steel and non-ferrous metal pipework components and materials shall not come into contact with carbon steel or low-alloy steel. The orifices of the pipes, valves and fittings that are not temporarily installed shall be closed.6 Fabrication of Piping6.1 Cutting and Joint Processing 6.1.1 The cutting processing of the pipework components and materials may adopt the method of cold cutting or hot cutting. If the method of hot cutting is used, after cutting, the method of mechanical processing or polishing shall be used to eliminate the surface slag and the surface layer that affects the quality of piping welding. 6.1.2 Carbon steel and carbon-manganese steel may adopt the method of mechanical processing or flame cutting to cut and prepare the joints. Low-temperature nickel steel and alloy steel should adopt the method of mechanical processing to cut and prepare the joints. 6.2 Mark Transference 6.2.1 During the fabrication of the piping components, the original marks of the materials shall be verified and kept as much as possible. When it is impossible to keep the original marks, the method of transference shall be adopted to re-mark the materials. The material marking may also adopt the uniform engineering codes or color codes of the piping components. 6.2.2 The use of marking method shall be based on the principle of not causing damage or contamination to the materials. Hard-printed markings shall not be used for low-temperature steel, stainless steel and non-ferrous metals. When austenitic stainless steel and non-ferrous metal materials are marked with color codes, the printing color shall not contain substances that may cause damage to the materials, such as. sulfur, lead and chlorine, etc. 6.2.3 If other marking methods other than hard printing or engraving are adopted, the fabricator shall ensure that there is no mixture of different materials, for example, through the method of separate processing (time and location) or distinguishing color strips. 6.3 Bent Pipes 6.3.1 When fabricating bent pipes, appropriate bending techniques and equipment shall be adopted in accordance with the properties of the pipe material, the working conditions of the conveying fluid and the bending radius of the pipes. 6.3.2 The fabrication of bent pipes may adopt two methods. hot bending and cold bending. 6.4 Plate Welded Pipes 6.4.1 The fabrication of the plate welded pipes shall comply with the stipulations of the design documents and the product standards. 6.4.2 When fabricating and erecting plate welded pipes with a nominal diameter not less than 400 mm, they shall comply with the following stipulations. 6.5 Miter Elbows7 Welding7.1 Welding Procedure Qualification and Welding Performance Qualification 7.1.1 The welding of piping pressure-bearing parts and pressure-bearing parts, as well as the welding of pressure-bearing parts and non-pressure-bearing parts, shall adopt qualified welding procedures and be welded by qualified welders. 7.1.2 The welding procedure qualification shall comply with the stipulations of NB/T 47014.The impact test requirements shall comply with the stipulations of 8.2 in GB/T 20801.2-2020. 7.1.3 When the materials required for the welding procedure qualification cannot satisfy the stipulations of 7.1.2, with the consent of the designer and the proprietor, it is allowed to use the mode of technical review of the pre-welding procedure specification to replace the welding procedure qualification, but the following conditions shall be satisfied at the same time. 7.2 Welding Materials 7.2.1 The welding materials shall comply with the stipulations of the design documents and the relevant standards, and pass the welding procedure qualification verification. When there is no stipulation in the design, the selection of welding materials shall be comprehensively determined in accordance with the chemical composition, mechanical properties, welding performance, pre-weld preheating, post-weld heat treatment, service conditions and on-site construction conditions of the base material, and comply with the following stipulations. 7.3.4 When welding in rainy and snowy days, effective protective measures shall be taken, otherwise, welding shall be prohibited. 7.4 Preparation before Welding 7.4.1 Preparation of joints 7.4.2 Cleaning 7.4.2.1 For weldment joints, and the internal and external surfaces, before welding, paint, oil stains, rust spots, slag, oxide scale and other detrimental substances shall be removed. 7.4.3 Assembly 7.4.3.1 The assembly of butt joints shall comply with the following stipulations. 7.7 Fillet Weld 7.7.1 The fillet welds (including socket welds) may be concave and convex, and the weld size shall comply with the stipulations of Figure 7. 7.7.2 The fillet welds of flat welded flanges or socket welded flanges shall comply with the stipulations of Figure 8.The minimum weld size of other socket welded joints shall comply with the stipulations of Figure 9. 7.8 Welded Connection of Branch Pipes 7.8.1 The welded connection between the branch pipe and the main pipe shall comply with the stipulations of weld form and weld size of the branch pipe connection shown in Figure 10. 7.8.2 The joints of the placed welded branch pipes or the plug-in welded branch pipes, including the integrally reinforced branch pipe seats, shall be fully welded; the thickness of the fillet weld of the cover surface shall be not less than the effective thickness of the fillet weld [see Figure 10a) and Figure 10b)]. 7.8.3 The welding of the reinforcement ring or the saddle-shaped reinforcement shall comply with the following stipulations. 7.8.7 The branch pipe seat and the main pipe shall be fully welded; the thickness of the fillet weld of the cover surface shall be not less than the effective thickness tc of the fillet weld [see Figure 10g)]. The fillet weld of the cover surface shall smoothly transit to the main pipe. 7.9 Welding of Attachments 7.10 Seal Welding Seal welding shall be performed by qualified welders. The sealing weld shall cover all exposed threads. 7.11 Weld Repair8 Preheating8.1 General Rules 8.1.1 The preheating requirements specified in this Chapter apply to all types of piping welding, including tack welding, repair welding and seal welding of threaded joints. 8.1.2 The preheating temperature and other requirements shall be specified in the welding procedure specification or the design documents, and verified by the welding procedure qualification. 8.1.3 When the method of thermal processing is used for the cutting, joint-opening, root cleaning, grooving or temporary welding of welds, the preheating requirements shall also be considered. 8.2 Preheating Temperature 8.2.1 The preheating temperature shall comply with the requirements of the design documents. When there is no such stipulation in the design documents, the minimum preheating temperature of the various materials shall comply with the stipulations of Table 6. 8.2.2 During the welding of materials with different requirements for the preheating temperature, the higher preheating temperature in Table 6 shall be selected. 8.2.3 For multi-layer (pass) weldments that require preheating, the interpass temperature shall be not lower than the preheating temperature, but shall comply with the following requirements. 8.2.4 The base material temperature of tack weld shall be not lower than the minimum preheating temperature specified in Table 6; the preheating range shall be no less than 25 mm from the two ends of the tack weld. 8.2.5 For repair welding, the preheating temperature shall be appropriately higher than that of the original weld. 8.3 Measurement of Preheating Temperature 8.4 Welding Interruption 8.4.1 When the welding is interrupted, the cooling rate shall be controlled, or other measures shall be taken to prevent it from adversely affecting the piping. 8.4.2 Before the welding is resumed, the interrupted weld shall be cleaned, inspected and confirmed. In addition, in accordance with the stipulations of the welding procedure specification, preheating shall be re-performed.9 Heat Treatment9.1 General Rules 9.1.1 This Chapter specifies the basic requirements for the welding, bending and post- forming heat treatment of pressure piping. 9.1.3 This Part does not restrict the use of lower or even exempt heat treatment requirements, but it shall comply with the requirements of 9.7. 9.2 Heat Treatment after Bending and Forming 9.6 Hardness Inspection 9.6.1 For welded joints, and piping components processed through bending and forming that require post weld heat treatment, after the heat treatment, the hardness value shall be determined. The hardness determination area of welded joints shall include welds and heat-affected zone. The determination area of the heat-affected zone shall be close to the fusion line. 9.6.2 For each heat treatment in the furnace, at least 10% shall be spot-checked for the determination of the hardness value. For partial heat treatment, 100% shall be tested for the hardness value. 9.6.3 Unless it is otherwise specified in the design, the hardness values of welded joints and piping components processed through bending and forming after heat treatment shall comply with the following stipulations. ......Source: Above contents are excerpted from the full-copy PDF -- translated/reviewed by: www.ChineseStandard.net / Wayne Zheng et al. Tips & Frequently Asked Questions:Question 1: How long will the true-PDF of English version of GB/T 20801.4-2020 be delivered?Answer: The full copy PDF of English version of GB/T 20801.4-2020 can be downloaded in 9 seconds, and it will also be emailed to you in 9 seconds (double mechanisms to ensure the delivery reliably), with PDF-invoice.Question 2: Can I share the purchased PDF of GB/T 20801.4-2020_English with my colleagues?Answer: Yes. 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