ASME B31, natural gas piping repairs

[Docseven]

Hello all,

I am in an engineering position at a power plant at which I am very new. I have not been involved with codes, etc in prior positions (more performance engineering work in prior work history). Right now I am working with a group developing a corporate procedure for natural gas purging/inerting in accordance with NFPA 56 and other applicable codes. I have a question about ASME B31 which I don't have access to via our web-access at the moment and was looking for a quick answer which I will certainly review against the actual code at my next opportunity.

Suppose that a threaded union or a threaded temperature/pressure gauge in a tap on a natural gas pipeline is replaced in-kind (after proper inerting per other applicable codes). Is this something that ASME would require a pressure test on prior to inerting and then purging back into service with natural gas again?

NFPA 56 states, "Where piping is designed and installed in accordance with ASME B31.1 Power Piping, pressure testing and inspection shall be in accordance with Chapter VI of ASME B31.1" As stated, I do not currently have that code and don't know if Chapter VI addresses my question.

I am looking for a very general answer on this question. Just wasn't sure if it only covers welded repairs or any such replacement (of a faulty pressure gauge which is threaded in, for instance).

Thank you

 

[metengr]

Ref; ASME B31.8, there would be no reason to perform a separate pressure test for a mechanical/threaded repair. Instead you should perform an in-service leak test using a soap snoop solution.