Allowable wall thickness difference in gas pipe

[71713]

I am relocating a section of a natural gas transmission line. The existing pipe is 16" diameter with 1/4" wall thickness. Pipe with a 3/8" wall is available.

Is there a maximum change in material thickness allowed in ASME B31.8 or Part 192 at a weld joint? Will this require a special weld procedure with adjacent materials differing in thickness?

 

[rconner]

Youmay be interested in a lengthy discussion not long ago of I believe similar issues on this same forum at

http://www.eng-tips.com/viewthread.cfm?qid=176732&page=6

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[BigInch]

Good you mentioned the B31.8 code which limits wt difference to <= 3/16" in wall thickness at the weld joint, which could therefore be made by taper boring only the pipe ends, if necessary.

No special weld proceedure is required when within the maximum allowed wall thickness difference, however pay attention to any difference in pipe materials that would otherwise take precedence.

BigInch-born in the trenches.

http://virtualpipeline.spaces.msn.com