Flaw detection ratio of pressure pipelines
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In the construction of pressure pipelines, the design documents do not stipulate the proportion of flaw detection, and the acceptance is stipulated in accordance with GB50235. Currently, there are several types of pipelines, such as: Compressed air, temperature 60 degrees, pressure 0.8MPa Nitrogen, temperature 60 degrees, pressure 0.8MPa What is the flaw detection ratio and what are the regulations? Thanks!
According to the following provisions of GB50235-97: 7.4.3.1 The following pipeline welds shall undergo 100% radiographic inspection, and their quality shall not be lower than Grade II: (1) Pipelines transporting highly toxic fluids ； (2) Pipelines transporting flammable fluids and toxic fluids with design pressures greater than or equal to 10MPa or design pressures greater than or equal to 4MPa and design temperatures greater than or equal to 400°C ； (3) Pipes transporting non-flammable fluids and non-toxic fluids with design pressures greater than or equal to 10MPa and design temperatures greater than or equal to 400°C ； (4) Low-temperature pipelines with a design temperature less than -29°C. (5) Other pipelines whose design documents require 100% radiographic inspection. 7.4.3.2 The welds of non-flammable fluid pipelines and non-toxic fluid pipelines that carry design pressures less than or equal to 1MPa and design temperatures less than 400°C do not need to undergo 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 their quality shall not be lower than Level III. The sampling ratio and quality level should comply with the requirements of the design documents. I don’t know if the pressure and temperature mentioned by the poster are the design values. If they are the design values, flaw detection is not required.
There are clear provisions in GB50235-97: “The welds of non-combustible fluid pipelines and non-toxic fluid pipelines that carry design pressures less than or equal to 1MPa and design temperatures less than 400°C do not need to undergo radiographic inspection. ” But a corresponding visual inspection should be carried out! For reference!
According to the latest version of industrial metal pipe design specifications (GB50316-2008): All Class D fluid (refers to non-flammable, non-toxic fluids with design pressure less than or equal to 1.0MPa and design temperature -20~186 degrees) pipelines are not subject to non-destructive testing. There is a note at the back: For Class D fluid pipelines, when spot inspections are required, it should be stipulated in the design documents that if the spot inspection fails, they should be repaired, but double spot inspections are not required.
Not required according to regulations. But this is the lowest, you can ask for 5%
Compressed air and nitrogen pipelines, based on 5%.
You can press 5% or 10%. It is also possible not to perform testing.
What is the flaw detection ratio of the 132kg Gaya nitrogen pipeline?
The construction drawings of pressure pipelines must indicate the flaw detection ratio, and the construction unit cannot determine it by itself.