Installation and inspection standards for industrial pipeline engineering (7)

The People’s Republic of China National Standard Industrial Metal Pipeline Engineering Construction and Acceptance Specification GB 50235-97 Article Description Revision Description This specification is based on the State Planning Commission’s Jisong [1991] No. 290 and the Ministry of Construction (91) Jianbiaozi No. 10 The requirements are edited by the Ministry of Chemical Industry, specifically by the Ministry of Chemical Industry Construction Standardization Management Center Station, the Ministry of Chemical Industry Construction Coordination Department, Electric Power Construction Research Institute, China Petrochemical Corporation Lanzhou Chemical Industry Company Construction Company, China Nuclear Industry Corporation 23 The company, China National Chemical Engineering Corporation and Jilin Chemical Industry Company Construction Company jointly revised the national standard “Code for Construction and Acceptance of Industrial Pipeline Engineering” (Metal Pipeline) GBJ 235-82. Approved by the Ministry of Construction with Jianbiao [1997] No. 278 on October 5, 1997, and jointly issued with the State Bureau of Technical Supervision. In the process of revising this code, the specification revision team conducted extensive investigations and studies, carefully summed up and absorbed the practical experience of China’s industrial metal pipeline construction, referred to relevant international standards and advanced foreign standards, and extensively solicited relevant units across the country. Views. Finally, the Ministry of Construction and the Ministry of Chemical Industry will review and finalize the draft. In the process of implementing the specification, it is hoped that all units combine engineering practice and scientific research, conscientiously sum up their experience, and pay attention to accumulating information, if they find that they need to be modified and supplemented. Please send your comments and related materials to the Construction Standardization Management Center Station of the Ministry of Chemical Industry (Address: Guzhong Middle Road, Shijiazhuang City, Zip Code 050021), and send a copy to the Ministry of Chemical Industry for reference in future revisions. 1 General 1.0.1 According to the regulations, an article on the purpose of formulating specifications is added. 1.0.2 The main changes in this article are as follows: (1) Because of the commonality of pipeline construction in various industries, industry restrictions have been removed. (2) The original regulations limit the design pressure to 3mmHg (absolute pressure) to 1000kgf/cm2, and the design temperature to be -200 to 850°C. According to the industrial piping design specifications, the pressure range is changed to no more than 42Mpa, and the temperature range is changed to “not exceeding the allowable use temperature of the material”. When the pressure exceeds 42 MPa, this code is not applicable, and the design documents should put forward specific requirements for welding, heat treatment, inspection, and testing. 1.0. 3 There are 6 non-applicable scopes stipulated in the original code, which are added or deleted as follows: (1) Because this code has been limited to “industrial metal pipes” in the name, “non-metal pipes” do not need to be further restricted in the provisions. So deleted. (2) The concept of “nuclear power pipeline” in Article 1.0.2 of the original code is unclear, and now it is changed to “special pipeline for nuclear energy installations”, which means that the general pipelines for nuclear energy installations are also within the scope of application of this specification. . (3) The equipment body piping is within the inapplicable scope of the original specification, and it is now restricted (see Article 1.0.5). (4) Instrument piping has always been constructed in accordance with this specification, so it is deleted from the scope of inapplicability. (5) This code retains three special pipelines for nuclear energy installations, special pipelines for mines, and long-distance pipelines in the non-applicable scope. 1.0.4, 1.0.5 The original specification only pointed out that the construction should be carried out according to the design, and did not clarify the relationship between the design documents and the specification and the manufacturer’s regulations. The revised specification clarifies that the construction should be implemented in accordance with the design documents and the regulations of the manufacturer. 1.0.6 Expanded and generalized on the basis of 1.0.8 and 1.0.9 of the original specification, and summarized all the content that should still be implemented with “should still implement relevant national standards and norms”. 3 Inspection of piping components and piping supports 3.0.1 Article 2.1.1 of the original specification stipulates that the manufacturer only needs to provide a certificate of conformity. Now it is clearly stipulated that it is a certificate of quality, not a certificate of conformity. 3.0.2 Two points are emphatically clarified: one is that the products provided by the supplier are required to meet the requirements of the design documents; the other is that the quality of the products supplied from outside is uneven, so it is stipulated that 100% appearance inspection of the products shall be carried out. This requirement It is stricter than the American standard ANSI/ASMEB31. 3.0.4 The compilation task of “Code for Construction and Acceptance of Industrial Equipment and Pipeline Anticorrosion Engineering” HGJ229-91 was directly issued by the Ministry of Construction. This code is a comprehensive national professional standard. 3.0.5 According to the American standard ANSI/ASMEB31.3 and combined with our country’s customary practices, the pipelines are divided into four categories: A, B, C, and D. Among them, category A, B and C pipelines are the same as those in the original specification. , Medium pressure and highly toxic, toxic, and Category A and B fire hazard material pipelines have basically the same meaning. Category D pipelines are equivalent to low-pressure pipelines for transporting non-combustible and non-toxic media, but within the temperature and pressure range of Category D pipelines. The above has been adjusted slightly to move closer to the American standard ANSI/A5ME B31. This provision is based on Article 2.5.1 and Article 2 of the original specification. Prepared in Article 5.2. The meaning of various types of pipelines has been stipulated in Chapter 2 of this code. 3.0.7 The original specification stipulates that when the nominal pressure is less than or equal to 320kgf/cm2, the test pressure shall be 1.5 times the nominal pressure. When the nominal pressure is equal to 400kgf/cm2, it is 1.4 times. Now according to the American standard ANSI/ASME B31, it is changed to 1.5 times. 3.0.8 In order to prevent corrosion, the requirement of drying after drainage has been added. 3.0.10 The safety valve trial adjustment is the inspection of the product, and the final adjustment will be carried out in the future, so the lead seal requirement is cancelled in this article. 3.0.12, 3.0.13 For austenitic stainless steels and low-temperature steels, the original specification only stipulates that supplementary tests are required. It is now clearly stipulated that the supplier and lender shall be responsible for providing the test results. 3.0.14 In order to strengthen management, improve the level of construction, and ensure the quality of the project, this code makes provisions for the proper storage of pipeline components and pipeline supports. At the same time, to ensure that stainless steel and non-ferrous metals are not “Plain steel contact”. 4 Pipeline processing 4.1 Pipe cutting 4.1.1 This article is rewritten in accordance with Article 3.1.6 of the original code and Article 5.2.1 of “Code for Construction and Acceptance of Titanium Pipelines” HGJ 217. Before the pipe is processed and cut, the original mark must be transplanted to ensure the correct identification of the material of the pipe. Titanium pipes are easily contaminated by iron ions, so steel stamps should not be used when transplanting marks. 4.1.2 After the carbon steel pipe and alloy steel pipe are cut by oxygen flame, they have little effect on the mechanical properties and metallographic structure of the base metal in the heat-affected zone. Therefore, this article only stipulates “to ensure the correct size and smooth surface”, and does not require removal The thickness requirements of the heat-affected zone. This article complies with the American standard ANSI/ASME B31. 4.1.3 When cutting and grinding stainless steel pipes and titanium pipes with grinding wheels, special grinding wheels should be used, and no grinding wheels for cutting carbon steel pipes should be used to avoid pollution and affect the quality of stainless steel pipes and titanium pipes. 4.2 Fabrication of elbows This section cancels outdated technologies such as folded elbows and welded elbows. This section is basically rewritten according to the American standard ANSI/ASME B31. 4.2.1 This article is a new article. Table 4.2.1 is quoted from Table 102.4.5 of American Standard ANSI/ASMEB31.1 (1992). When the operation is correct, making the elbow pipe according to the minimum thickness of the straight pipe listed in the table can meet the requirements of the design document. 4.2. 3 Rewritten according to the original specification. However, the “Longitudinal Welding Seam Arrangement Area” drawing is cancelled and replaced by text. 4.2.4 Refer to the American standard ANSI/ASME B31 for the definition of cold bending and hot bending. 4.2.7 This clause is adapted from the American standard ANSI/ASME B31.1. In B31, B31.1 and B31.3 are very different in determining whether the pipe needs heat treatment after bending. The former mainly depends on the nominal diameter and wall thickness of the pipe, and the latter is determined by the maximum fiber elongation after bending. , And the specified elongation varies with the width and material of the tensile sample. As China currently does not have various material allowable elongation and the requirement of determining the corresponding width of the sample based on the nominal pipe diameter, this code is based on the United States Standard ANSI/ASME B31.1 was rewritten. The main changes of the revised specification are as follows: (1) The heat treatment restriction conditions of carbon steel elbows are stricter than the original specification. The original specification stipulates that when the carbon steel pipe is bent in the temperature range of 1050 to 750°C, no heat treatment is required for any wall thickness. Now it is changed to require heat treatment when the wall thickness is greater than 19mm below 900°C. (2) The original specification stipulates that when carbon steel pipes are cold-formed, if the wall thickness is greater than or equal to 36mm, all need heat treatment. Now the 36mm is changed to 19mm. (3) The original specification stipulates that when chromium-molybdenum steel pipes with any wall thickness are hot-bent, normalizing, complete annealing, high temperature tempering, normalizing and high temperature tempering should be used for heat treatment. Now, when the nominal diameter is greater than or equal to 100mm or the wall thickness is greater than or equal to 13mm, the designer shall determine the use of full annealing, normalizing and tempering or tempering heat treatment. (4) The original specification stipulates that chromium-molybdenum steel pipes with a wall thickness greater than or equal to 20mm require heat treatment when cold bending. Now it is changed to require heat treatment when the nominal diameter is greater than or equal to 100mm or the wall thickness is greater than or equal to 13mm. (5) The original specification stipulates that the austenitic stainless steel pipe needs to be quenched during hot bending, and cold bending is not required. Now it is changed to no matter whether hot bending or cold bending, heat treatment is not required. If processing is required, it should be carried out in accordance with the design documents. 4.2.8 The original code regards the ellipticity of the elbow as a quality requirement, while the American standard ANSI/ASME B31 does not use the ellipticity. The latter’s regulations are more in line with the characteristics of bending than as a measure. This article is rewritten based on the American standard ANSI/ASME B3l. 4.2. 9 This article is added in accordance with the relevant content in the industry standard of the Ministry of Electric Power “Power Station Bend”. 4.3 Coil tube processing 4.3.1 This article is rewritten according to Article 3.3.1 of the original specification. In the implementation of the original specification, the loss of steel is relatively large. According to the current welding technology level and quality assurance system, when the distance between the two longitudinal seams of coiled pipes of various diameters is greater than 200mm, the quality of the coiled pipe can be guaranteed, so the longitudinal seam spacing is changed to 300mm Reduced to 200mm. 4.3.2 This article is rewritten according to Article 3.3.2 of the original specification. Since it is not advisable to open a hole to weld branch pipes near the weld, the rule “if the weld is inspected by non-destructive flaw detection is not subject to this limitation” is deleted. 4.3.3 In this article, it is more precise to change the “longitudinal seam” in Article 3.3.3 of the original code to “butt weld seam”. 4.3.4~4.3.9 Rewrite according to the content of Article 3.3.4~3.3.10 of the original specification. (1) Article 3.3.7 of the original specification is deleted. Since the content of this article is purely a welding method, it should not be specified in this code. (2) Added “The processing specifications and dimensions of the coiled tube should meet the requirements of the design documents”. 4.4 Nozzle flanging 4.4.1 Rewritten according to Article 2.4.6 of the original specification. Delete the word “annealing” in the original text because “annealing” is not the only way to eliminate cracks in non-ferrous metal pipes. For example, aluminum pipes need to be annealed, while copper pipes need to be quenched. Therefore, this article only provides for handling, not for handling methods. 4.5 Jacketed sleeve processing 4.5.1 The reserved adjustment margin is 50~l 00mm, which not only takes into account the convenience of installation, but also ensures the correctness of the installation dimensions. 7 articles. Since the content of this article is purely a welding method, it should not be specified in this code. (2) Added “The processing specifications and dimensions of the coiled tube should meet the requirements of the design documents”. 4.4 Nozzle flanging 4.4.1 Rewritten according to Article 2.4.6 of the original specification. Delete the word “annealing” in the original text because “annealing” is not the only way to eliminate cracks in non-ferrous metal pipes. For example, aluminum pipes need to be annealed, while copper pipes need to be quenched. Therefore, this article only provides for handling, not for handling methods. 4.5 Jacketed sleeve processing 4.5.1 The reserved adjustment margin is 50~l 00mm, which not only takes into account the convenience of installation, but also ensures the correctness of the installation dimensions. 7 articles. Since the content of this article is purely a welding method, it should not be specified in this code. (2) Added “The processing specifications and dimensions of the coiled tube should meet the requirements of the design documents”. 4.4 Nozzle flanging 4.4.1 Rewritten according to Article 2.4.6 of the original specification. Delete the word “annealing” in the original text because “annealing” is not the only way to eliminate cracks in non-ferrous metal pipes. For example, aluminum pipes need to be annealed, while copper pipes need to be quenched. Therefore, this article only provides for handling, not for handling methods. 4.5 Jacketed sleeve processing 4.5.1 The reserved adjustment margin is 50~l 00mm, which not only takes into account the convenience of installation, but also ensures the correctness of the installation dimensions.