Non-destructive testing of high-pressure pipelines
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In this project, there are several pipes with a pressure of less than 4 MPa and a temperature of less than 400 degrees; the media handled are of Class A or B. In accordance with the SH 3501-2011 \"Code for Construction and Acceptance of Steel Piping Systems for Toxic and Flammable Media in Petrochemical Industries\", these pipes fall under categories GC2 and SHB3. A 5% test is sufficient. According to GB 50184-2011 \"Code for Acceptance of Construction Quality of Industrial Metal Piping Projects\", it is also at this grade. However, considering the temperature and pressure profiles of the stainless steel flanges, the engineering design set these pipelines’ PN values at 64 and 100. Is it still possible to conduct a 5% test at this time?
Whether it is SH3501 or GB50235, the determination of the flaw detection ratio for different pipeline grades is based on the design pressure and design temperature of the pipelines, and it has nothing to do with the nominal pressure rating of the pipeline components. So, regardless of the PN or CL value, it is not necessary to determine the flaw detection level based on the nominal pressure at any time. Follow the WeChat official account of Pressure Pipeline People to learn more relevant knowledge.
Setting a standard detection ratio for Alipay represents the minimum requirement; meeting this ratio ensures compliance with **’s review and regulatory standards. For pipes that the designer or owner considers important or hazardous, a higher inspection rate than that specified in the codes can be required.
According to the relevant provisions of GBT20801: If the pipes referred to by the owner are made of austenitic stainless steel, the inspection rate must be no less than 10%. Except for GC3-grade pipes, the inspection grade for the following pipes shall be no less than Grade III: 1) Carbon steel pipes with a nominal pressure not exceeding PN50 (impact testing is required per these specifications)； 2) Austenitic stainless steel pipes with a nominal pressure not exceeding PN110. The radiographic inspection ratio corresponding to grade III is 10%
The engineering design specifies these pipeline PN values as 64 and 100. What does “?” mean? Is the design pressure being increased to 6.3 MPa?
In all cases, the pipeline grade should be determined based on the design pressure and design temperature, rather than the actual operating conditions. In your case, even at the SHB3 level, the testing rate should be 10%, with the qualified level being III ； If the design pressure is increased to 6.3 MPa or 10.0 MPa, then the grade should be SHB1, with a testing rate of 100%
The design pressure has not increased, but the nominal pressure has been raised to 6.3 MPa and 10.0 MPa. Should the grade be SHB? , detection ratio? %.
It should be determined based on the design pressure, right?
The design pressure is not high, but due to corrosion resistance requirements, 304L was selected. Based on the temperature-pressure curve, the nominal pressure was increased to 6.3 MPa and 10.0 MPa.