Industrial piping engineering installation and standard specifications (8)

5 Pipe welding 5.0.2 Article 5.2.19 of the original code stipulates that “the distance between the two circumferential seams of a straight pipe section shall not be less than 100 mm”. It is now coordinated with the “Technical Specifications for Acceptance of Electric Power Construction Construction”, and after discussion at the review meeting, it should be changed to “When the nominal diameter is greater than or equal to 150mm, it should not be less than 150mm; when the nominal diameter is less than 150mm, it should not be less than the outside diameter of the pipe”. 5.0.4 There are many processing methods for pipe bevels. For bevels processed by mechanical methods, the surface of the bevel is relatively smooth and the size is accurate. The mechanical method should be adopted in this article. With the advancement of technology, the quality of flame cutting grooves can meet the requirements, so there is no need to limit the processing of grooves by thermal processing methods. Therefore, it is stipulated that thermal processing methods such as plasma and oxygen flame can be used to process the groove, but after thermal cutting, the oxide scale, slag and surface layer that affect the quality of the joint must be removed. 5.0.5 Table 5.0.5 adds the requirements for titanium materials. 5.0.7 The original specification stipulated different amount of misalignment according to the weld level. Now it is rewritten in accordance with the “Code for Construction and Acceptance of Field Equipment and Industrial Pipeline Welding Engineering”. %, and not more than 2mm”, which is equivalent to the requirements of the original code for class III and IV welds and is consistent with the American standard ANSI/ASME D31.1. 5.0.8 When the pipes and fittings of unequal thickness are assembled, the inner wall should be flush. When the inner diameter is different, it should be processed. When the outer wall has a large amount of deviation, it should be processed into a gentle slope and smooth transition. 5.0.10 This article is a newly-added article, according to the American standard ANSI/ASME B31.3 put forward the requirements for the sealing welding of threaded joints. 5.0.11 Provisions are made for the welding of pipes with high requirements for cleanliness in the pipes. These pipes include turbine inlet pipes and boiler feed water pipes. Circulating oil, control oil, and sealing oil pipelines of the unit. This article is quoted from Article 5.2.21 of the original specification. 6 Pipeline installation 6.1 General provisions 6.1.1 This article is rewritten according to Article 5.1.1 of the original code. The paragraph “and possess the relevant technology” is deleted. Various technologies have been tested in Chapter 3 “Inspection of Pipe Supports”, so there is no need to repeat the work here. 6.1.3 This article is rewritten in accordance with Article 5.1.6 of the original specification. Amend the paragraph “Whether there are oil stains on the internal and external surfaces. If oil stains are found, they must not be installed and should be renewed and degreasing treatment.” Amended to: “No oil stains shall be allowed”. The quality standard is stipulated and the text is refined. 6.1. 4 This article is rewritten in accordance with Article 5.1.9 of the original specification. The “pipeline crossing road” in the original text is revised to: “pipeline crossing road, wall and structure”, which increases the applicability of this article. 6.2 Pipeline prefabrication 6.2.1 The piping system single-line drawing is the processing drawing of the piping prefabrication. According to the material table of the drawing, the quantity and specifications of the materials can be verified. The blanking size can be marked on the piping system single-line drawing to reduce construction errors and confirm Close the pipe section, leaving a processing margin or pipe section to be measured. Therefore, in the pipeline prefabrication work, it is a better construction method to implement it according to the single-line drawing of the pipeline system. 6.2.2 The piping system number in the one-line diagram of the piping system corresponds to the piping system number in the process piping, and is the same pipeline. Therefore, the piping system number indicates the position of the pipeline in the process piping and the medium passing through the pipe , The nominal diameter of the pipeline, the pipeline sequence number, and the pipeline grade classification number, etc. In the process of pipeline prefabrication, not only must strictly follow the piping system number indicated on the one-line diagram, but also the piping system number should be marked on the prefabricated piping so as to “check the number of seats” during installation. In addition, for the smooth progress of pipeline prefabrication. To ensure the quality of work and reduce work errors, the sequence number of each component should be marked in the prefabricated sequence. 6.2.4 The allowable deviation of the processing size of the prefabricated pipe section is mainly based on practical experience and combined with the combined size deviation of the low pre-compressed pipe section in Article 3.11.2 of the original code. 6.2.5 The nature of the work of pipeline prefabrication and on-site piping is the same, but the work location is different. Therefore, the work quality should also comply with the relevant provisions of this code. 6.2.6 For the prefabricated pipe section, no matter during storage or transportation, external dirt can easily enter the pipe. Therefore, after the pipe section is prefabricated, the inside of the pipe should be cleaned first, and then the pipe mouth should be closed. Ensure the installation quality of the pipeline. 6.3 Installation of steel pipes 6.3.1 This article is a new article. In order to be consistent with the content of Section 6.2 of this chapter, the content of this provision is added. 6.3.3 This article is rewritten in accordance with Article 5.2.6 of the original specification. For large-diameter medium and low-pressure pipelines, sometimes suitable gaskets cannot be purchased and need to be made on site. The oblique lap joint specified in this article requires the contact surface of the two gaskets to be thinned at the interface to make them overlap and flat to ensure the sealing performance of the gasket interface. 6.3.5 This article is in accordance with Article 5.2 of the original specification. 3 broken writing: a paragraph “when no annealing treatment is performed before leaving the factory” is added to limit the annealing treatment conditions before installation. 6.3.6 This article is rewritten in accordance with Article 5.2.3 and Article 5.2.4 of the original specification. Delete the paragraph “Bolt hole center deviation generally does not exceed 5% of the hole diameter”. If the screw can penetrate the bolt hole freely, it means that the flange and the pipe are concentric. Therefore, there is no need to specify the center deviation of the bolt hole. 6.3.8 This article is rewritten in accordance with Article 5.2.10 and Article 5.2.11 of the original code and with reference to the relevant content of the American Standard ANS1/ASME B31.3. Amend “The exposed length after tightening is not more than 2 times the pitch” to: “The bolts and nuts after tightening should be flush.” For the exposed length of bolts, most of the relevant regulations of our country stipulate 2~3 buckles, such as the “Technical Specification for Construction and Acceptance of High-Pressure Steel Pipelines” stipulates no less than 2 buckles; “Interim Technical Code for Construction and Acceptance of Electric Power Construction” (Pipeline) Regulations 2~buckles; “Construction and Installation Engineering Quality Inspection and Evaluation Standards” (Industrial Piping Engineering) stipulates 2~3 buckles; “Industrial Piping Engineering Construction and Acceptance Specifications” (Metal Pipes) stipulates that the pitch is not more than 2 times the pitch and so on. The American standard ANSI/ASMEB31.3 stipulates: “All bolts are best to be screwed into the thickness of the nut…. If the thread that is not fully engaged is not more than 1 buckle, it can still be considered qualified.” The exposed length of the bolt has the following problems: (1) The exposed thread is caused by paint, rust or damage. It is difficult to disassemble, and it is often necessary to cut during maintenance, which is very wasteful. (2) The exposed thread has no meaning to the strength of the bolt connection, but it increases the workload of loading and unloading. (3) Due to the increase in the total length of the bolts, more steel is consumed and the amount of cutting is increased. Increased costs. We believe that the provisions of the American standard are reasonable, so it is stipulated that “the bolts and nuts after tightening should be flush.” 6.3.10 This article is rewritten according to Article 5.2.12 of the original specification. Tighten the hot or cold tightening time from the original maintaining working temperature for 24h. Change to 2h later. After the pipeline enters the working state, the expansion and contraction due to the increase or decrease of the pipeline temperature causes the tightened bolts to become loose at normal temperature. Practice has proved that when the pipeline enters the working state, it will not take a long time to cause the bolts to loosen. Too long, it may damage the flange gasket or the insulation layer. Experience has proved that it is more appropriate to maintain the working temperature for 2h after hot or cold fastening. 6.3.11 This article is in accordance with Article 5.2 of the original specification. Article 13 is rewritten. Practice has proved that when the diameter of the pipe is large, the specified allowable deviation is 1mm/m, which is difficult to achieve and difficult to measure. For this reason, this article rewrites the original regulations as: “When the nominal diameter of the pipe is less than 100mm, the allowable deviation is 1mm; when the nominal diameter of the pipe is greater than or equal to 100mm, the allowable deviation is 2mm”. Enhance the applicability of this provision. 6.3.14 This article is rewritten according to Article 5.1.5 of the original specification. The paragraph “If necessary, comply with relevant welding regulations” is deleted to emphasize the requirement that temporary supports are not allowed to be welded on alloy steel tracks. 6.3.22 is quoted from Article 5.2.27 of the original specification. The “chloride ion content shall not exceed 50×10-6 (50ppm)” is made through experiments. 6.3.23 This article is rewritten according to Article 5.2.28 of the original specification. Rewrite “plastic or rubber gasket without chloride ion” as: “non-metallic gasket with chloride ion content not exceeding 50×10-6 (50ppm)”. Use plastic or rubber gaskets that do not contain chloride ions. For stainless steel, the requirements are somewhat high, because no more than 50×10-6 (50ppm) chloride ions are allowed in flange gaskets in contact with stainless steel. Therefore, this article has been rewritten in consideration of the above circumstances. 6.3.25, 6.3.26 refer to Article 5.3.9 and Article 5.3.10 of the original specification. After the pipeline is installed, each group of measuring points should be measured and recorded. In the future overhaul, each group of creep expansion measuring points should be measured. In order to ensure the accuracy and comparability of the creep measurement results, a unified measurement and Calculation method. 6.3.27 This article is rewritten according to Article 5.3.11 of the original specification. Change the “re-check steel number” to “inspect the steel number”. In Chapter 3 of this code, the materials of alloy steel pipe components have been reviewed and marked. There is no need to re-check here, so the “inspection” is used. The words are more precise. 6.3.28 This article is rewritten according to Article 5.2.29 of the original specification. Due to the limited operating conditions of buried pipelines, underground construction will not be able to guarantee the construction quality of the anti-corrosion layer. Therefore, this code stipulates that the anti-corrosion layer should be prepared before installation. However, the welded joints need to be inspected by pressure test. Therefore, it is stipulated that the welded joints must be installed and pass the pressure test before they can be anti-corrosion. 6.3.29 Rewritten according to the relevant content of the current national standard “Quality Inspection and Evaluation Standards for Industrial Metal Piping Engineering”. 6.5 Installation of cast iron pipes 6.5.2 This article is in accordance with Article 5.5 of the original code. 3 rewrites. Delete the stipulation that “the axial gap should be determined according to the length of the pipe, the temperature of the medium and the temperature during construction”, because the minimum axial gap specified in this article is summarized according to the length of the pipe, the temperature of the medium and the changes in the temperature during construction. Therefore, the above content is deleted and the construction experience is directly adopted. Cast iron pipes are generally laid in a straight line. Therefore, the stipulation of laying along a curve in the original table is deleted. 6.5.3 This article is rewritten in accordance with Article 5.5.5 of the original specification. Delete the paragraph “The value and allowable deviation shall meet the requirements of Table 5.5.5”. Since the annular gap of the cast iron pipe socket interface is not as regular as machining, only stipulating that the “annular gap should be uniform” can guarantee the installation quality. 6.6 Installation of non-ferrous metal pipelines 6.6.9 Compiled in accordance with the current national standard “Code for Construction and Acceptance of Titanium Pipelines” HGJ 217. Since titanium pipes are easily contaminated by iron ions, construction personnel are reminded to avoid direct contact with titanium pipes by iron tools during handling and hoisting. 6.6.10 Compiled in accordance with HGJ 217 “Code for Construction and Acceptance of Titanium Pipelines”. During the construction process, due to the cross operation, the adjacent titanium pipes are easily affected by welding spatter from other pipes. Therefore, this article puts forward strict requirements on welding effects. 6.7 Installation of heat tracing pipe and jacket tube 6.7.1 This article is rewritten according to Article 5.7.2 and Article 5.7.4 of the original code. The “self-draining” provided in this article refers to allowing the condensate to be discharged by itself without any external force, rather than “draining.” 6.7.2 This article is rewritten based on part of the content in Article 5.7.3 and Article 5.7.4 of the original specification. In order to protect the material of the main pipe from damage, this provision adds “No heat tracing pipe 9 Compiled in accordance with the current national standard “Code for Construction and Acceptance of Titanium Pipelines” HGJ 217. Since titanium pipes are easily contaminated by iron ions, construction personnel are reminded to avoid direct contact with titanium pipes by iron tools during handling and hoisting. 6.6.10 Compiled in accordance with HGJ 217 “Code for Construction and Acceptance of Titanium Pipelines”. During the construction process, due to the cross operation, the adjacent titanium pipes are easily affected by welding spatter from other pipes. Therefore, this article puts forward strict requirements on welding effects. 6.7 Installation of heat tracing pipe and jacket tube 6.7.1 This article is rewritten according to Article 5.7.2 and Article 5.7.4 of the original code. The “self-draining” provided in this article refers to allowing the condensate to be discharged by itself without any external force, rather than “draining.” 6.7.2 This article is rewritten based on part of the content in Article 5.7.3 and Article 5.7.4 of the original specification. In order to protect the material of the main pipe from damage, this article adds “No heat tracing pipe 9 Compiled in accordance with the current national standard “Code for Construction and Acceptance of Titanium Pipelines” HGJ 217. Since titanium pipes are easily contaminated by iron ions, construction personnel are reminded to avoid direct contact with titanium pipes by iron tools during handling and hoisting. 6.6.10 Compiled in accordance with HGJ 217 “Code for Construction and Acceptance of Titanium Pipelines”. During the construction process, due to the cross operation, the adjacent titanium pipes are easily affected by welding spatter from other pipes. Therefore, this article puts forward strict requirements on welding effects. 6.7 Installation of heat tracing pipe and jacket tube 6.7.1 This article is rewritten according to Article 5.7.2 and Article 5.7.4 of the original code. The “self-draining” provided in this article refers to allowing the condensate to be discharged by itself without any external force, rather than “draining.” 6.7.2 This article is rewritten based on part of the content in Article 5.7.3 and Article 5.7.4 of the original specification. In order to protect the material of the main pipe from damage, this article adds “No heat tracing pipe