The issue of the RT inspection ratio for pressure pipelines
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There is a current project involving the installation of pressure pipelines, which primarily involves the welding of S32750 seamless steel pipes. The work is designed and manufactured in accordance with GC2 standards, and a flaw detection rate of 20% is required. I would like to know whether this 20% figure is calculated based on the number of circumferential welds or as 20% of the total length of all welds.
This post was last edited by SDHZZXM on 2017-11-8 at 14:20. When the nominal diameter of the pipe is less than 500, it is calculated based on the number of circumferential welds...
According to the GB20801-2006 standard, when the nominal diameter of the pipeline is 500 mm or greater, each circumferential weld is subject to local inspection at a rate based on the total length of the welds. When the nominal diameter of the pipeline is less than 500 mm, the ratio can be calculated based on the number of circumferential joint sections.
The proportion of non-destructive testing refers to the “length ratio”. For pipes, you can estimate the length based on the number of welds. Moreover, the drawings usually state “≥20%”, and it’s not 20% of something specific like Ding or Mao.
http://bbs.hcbbs.com/thread-792758-2-1.html
When the nominal diameter of the pipeline is 500 mm or greater, each circumferential weld is inspected at a rate of ≥20%. When the nominal diameter of the pipeline is less than 500 mm, 40% of the circumferential seams can be inspected at a rate of ≥20%.
Is it still necessary to conduct random inspections by separate welders?