Installation and Acceptance Standards for Industrial Piping Engineering (3)

7 Pipeline inspection, inspection and testing 7.1 General requirements 7.1.1 The construction unit shall inspect the construction quality through its quality inspectors. 7.1.2 The construction unit or its authorized institution shall supervise and inspect the construction quality through its quality inspectors. 7.2 Appearance inspection 7.2.1 Appearance inspection shall include inspection of various pipeline components, pipeline supports, and inspection during pipeline construction. 7.2.2 The inspection quantities and standards for pipeline components and pipeline supports, pipeline processing parts, bevel processing and assembly, and pipeline installation shall comply with the relevant regulations in Chapters 3 to 6 of this code. 7.2.3 Except for the welds with special requirements in the welding operation instruction, the slag and spatter shall be removed immediately after welding, and the surface of the weld shall be cleaned and visual inspection shall be carried out. 7.2.4 The quality of appearance inspection of pipeline welds shall comply with the relevant provisions of the current national standard “Code for Construction and Acceptance of Field Equipment and Industrial Pipeline Welding Engineering”. 7.3 Non-destructive inspection of the surface of the welding group 7.3.1 The surface of the weld shall be subjected to magnetic particle or liquid penetration inspection as specified in the design documents. 7.3.2 Welds with hot cracking tendency shall be inspected after heat treatment. 7.3.3 Magnetic particle inspection and liquid penetration inspection shall be carried out in accordance with the current national standard “Non-destructive Testing of Pressure Vessels”. 7.3.4 When defects on the weld surface are found, they should be eliminated in time. After the elimination, the inspection shall be carried out again until it is qualified. 7.4 Radiographic inspection and ultrasonic inspection 7.4.1 The internal quality of pipeline welds shall be subjected to radiographic inspection or ultrasonic inspection as specified in the design documents. The methods and quality grading standards of radiographic inspection and ultrasonic inspection shall comply with the current national standard “Code for Construction and Acceptance of Field Equipment and Industrial Pipeline Welding Engineering”. 7.4.2 Radiographic inspection or ultrasonic inspection of pipeline welds shall be carried out in time. When sampling inspections, spot checks shall be conducted on the proportion of welds welded by each welder, and the inspection location shall be jointly determined by the construction unit and the quality inspector of the construction unit. 7.4.2 The number of radiographic inspections of pipeline welds shall meet the following requirements: 7.4.3.1 The following pipeline welds shall undergo 100% radiographic inspection, and their quality shall not be lower than Class II: (1) Pipelines carrying highly toxic fluids; ( 2) Pipes that transport combustible fluids and toxic fluids with a design pressure greater than or equal to 10 MPa or a design pressure greater than or equal to 4 MPa and a design temperature greater than or equal to 400 ℃; (3) Transport non-flammable fluids with a design pressure greater than or equal to 10 MPa and a design temperature greater than or equal to 400 degrees C , Non-toxic fluid pipelines; (4) Low-temperature pipelines with a design temperature of less than -29°C. (5) Other pipelines that require 100% radiographic inspection in the design documents. 7.4.3.2 The welds of non-flammable fluid pipes and non-toxic fluid pipes with a design pressure of 1 MPa or less and a design temperature of less than 400 ℃ may not be subjected to radiographic inspection. 7.4.3.3 Other pipelines shall be subject to sampling radiographic inspection, the sampling rate shall not be less than 5%, and the quality shall not be less than Grade III. The sampling ratio and quality level shall meet the requirements of the design documents. 7.4.4 With the consent of the construction unit, the inspection of pipeline welds can be carried out by ultrasonic inspection instead of radiographic inspection, and the number of inspections shall be the same as that of radiographic inspection. 7.4.5 For welds that do not require internal quality inspection, the quality inspector shall conduct all appearance inspections in accordance with the provisions of Section 7.2 of this chapter. 7.4.6 When the inspection finds that the weld defect exceeds the design documents and this code, it must be repaired. After the weld is repaired, the inspection shall be carried out according to the original prescribed method. 7.4.7 When the welding seam defect that needs to be repaired is not found in the sampling inspection, the batch of welds represented by this sampling shall be deemed as qualified; when the welding seam defect that needs to be repaired is found in the sampling inspection, except for the welding seam to be repaired , The original prescribed method shall be used for further inspection according to the following provisions: 7.4.7.1 For each unqualified weld, two welds of the same batch welded by the welder shall be inspected. 7.4.7.2 When both welds are qualified, the batch of welds represented by the inspection shall be considered. 7.4.7.3 When these two welds are unqualified again, each unqualified weld shall be inspected again for two welds of the same batch of the welder. 7.4.7.4 When the welds inspected again are all qualified, the batch of welded seams represented by the inspection can be considered. 7.4.7.5 When the re-inspection fails again, all the welds of the same batch welded by the welder shall be inspected. 7.4.8 For welds requiring heat treatment, the hardness values ​​of the welds and the heat-affected zone shall be measured after heat treatment, and the hardness values ​​shall meet the requirements of the design documents. When there is no clear stipulation in the design document, carbon steel should not be greater than 120% of the base metal hardness; alloy steel should not be greater than 125% of the base metal hardness. The inspection quantity shall not be less than 10% of the total number of heat-treated welds. 7.4.9 For pipeline welds that require heat treatment, the “heat treatment report” shall be filled out in the format specified in Article A.0.7 of Appendix A of this code. 7.5 Pressure test 7.5.1 After the pipeline has been installed and passed the heat treatment and non-destructive inspection, a pressure test shall be carried out. The pressure test shall meet the following requirements: 7.5.1.1 The pressure test shall use liquid as the test medium. When the design pressure of the pipeline is less than or equal to 0.6MPa, gas can also be used as the test medium, but effective safety measures should be taken. It is strictly forbidden to use gas for pressure test on brittle materials. 7.5.1.2 When the site conditions do not allow the use of liquid or gas for pressure testing, the following methods can be used instead with the consent of the construction unit: (1) All welds (including welds on attachments), use liquid penetration method or Magnetic particle method for inspection. (2) Use 100% radiography for inspection of butt welds. 7.5.1.3 When performing pressure test, a restricted area should be delineated, and irrelevant personnel are not allowed to enter. 7.5.1.4 After the pressure test is completed, no repairs should be made on the pipeline. 7.5.1.5 The construction unit shall participate in the pressure test. After the pressure test is qualified, the “Piping System Pressure Test Record” shall be filled in with the construction unit in the format specified in Article A.0.8 of Appendix A of this Code. 7.5.2 The following conditions shall be met before the pressure test: 7.5.2.1 The pipeline installation works within the test range have been completed in accordance with the design drawings except for painting and heat insulation, and the installation quality shall comply with relevant regulations. 7.5.2.2 The welds and other parts to be inspected have not been painted and insulated. 7.5.2.3 Temporary restraint devices have been set up on the expansion joints on the pipeline. 7.5.2.4 The test pressure gauge has been calibrated, and during the weekly inspection period, its accuracy shall not be less than 1.5, the full scale value of the gauge shall be 1.5~2 times the maximum pressure to be measured, and the pressure gauge shall not be less than two . 7.5.2.5 The liquid or gas that meets the pressure test requirements has been prepared. 7.5.2.6 According to the requirements of the test, the pipeline has been reinforced. 7.5.2.7 For pipelines carrying highly toxic fluids and pipelines with a design pressure greater than or equal to 10MPa, before the pressure test, the following materials have been reviewed by the construction unit: (1) Quality certificate of the pipeline components. (2) Inspection or test records of pipeline components. (3) Pipe processing records. (4) Welding inspection and heat treatment records. (5) Design modification and material substitution documents. 7.5.2.8 The pipeline to be tested and the irrelevant system have been separated by blind plates or other measures. 7.5.2.9 The safety valve, blasting panel and instrument components on the pipeline to be tested have been removed or isolated. 7.5.2.10 The test plan has been approved, and technical clarifications have been made. 7.5.3 The hydraulic test shall comply with the following requirements: 7.5.3.1 Clean water shall be used for the hydraulic test. When testing austenitic stainless steel pipes or pipes connected to austenitic stainless steel pipes or equipment, the chloride ion content in the water shall not exceed 25×10‾6(25ppm). When a flammable liquid medium is used for testing, its flash point shall not be lower than 50°C. 7.5.3.2 Before the test, the air should be exhausted when the liquid is injected. 7.5.3.3 During the test, the ambient temperature should not be lower than 5℃. When the ambient temperature is lower than 5℃, anti-freezing measures should be taken. 7.5.3.4 During the test, the test temperature should be measured, and the test temperature of the material should not be close to the brittle transition temperature. 7.5.3.5 The test pressure of the above-ground steel pipes and non-ferrous metal pipes under internal pressure shall be 1.5 times the design pressure, and the test pressure of the buried steel pipes shall be 1.5 times the design pressure, and shall not be lower than 0.4MPa. 7.5.3.6 When the pipeline and equipment are tested as a system, and the test pressure of the pipeline is equal to or less than the test pressure of the equipment, the test shall be carried out according to the test pressure of the pipeline; when the test pressure of the pipeline is greater than the test pressure of the equipment, and the test pressure of the equipment When it is not less than 1.15 times the design pressure of the pipeline, the test can be carried out according to the test pressure of the equipment with the consent of the construction unit. 7.5.3.7 When the design temperature of the pipeline is higher than the test temperature, the test force shall be calculated as follows: Ps=1.5P[σ]1/[σ]2 (7.5.3) where Ps——test pressure (table Pressure) (Mpa); P —— design pressure (gauge pressure) (MPa); [σ] 1 —— allowable stress of the pipe at the test temperature (MPa); [σ] 2 —— at the design temperature of the pipe Allowable stress (MPa). When [σ]1/[σ]2 is greater than 6.5, take 6.5. When Ps generates a stress exceeding the yield strength at the test temperature, the test pressure Ps should be reduced to the maximum pressure that does not exceed the yield strength. 7.5.3.8 When the design pressure is less than or equal to 0.5MPa, the test pressure of the buried cast iron pipeline that is subjected to internal pressure shall be twice the design pressure; when the design pressure is greater than 0.5MFa, the design pressure shall be added 0.5MPa. 7.5.3.9 For pipelines with large displacements, the static pressure of the test medium shall be included in the test pressure. The test pressure of the liquid pipeline shall be based on the pressure at the highest point, but the pressure at the lowest point shall not exceed the bearing capacity of the pipeline components. 7.5.3.10 For pipelines subjected to external pressure, the test pressure should be 1.5 times the difference between the design internal and external pressures, and should not be less than 0.2MPa. 7.5.3.11 The test pressure of the inner tube of the jacketed tube shall be determined according to the higher of the internal or external design pressure. The test pressure of the outer tube of the jacketed casing shall be carried out in accordance with the provisions of paragraph 7.5.3.5. 7.5.3.12 The hydraulic pressure test should be increased slowly, after reaching the test pressure, stabilize the pressure for 10 minutes, then reduce the test pressure to the design pressure, and stop the pressure for 30 minutes