B31.1 Distance between two adjacent buttwelds

[kenmac777]

Is anyone aware of a prohibition on the minimum spacing between two adjacent butt-welds in B31.1 Boiler External Piping? Do any of the ASME Codes restrict this spacing?
My tradesmen tell me that 1-1/2 diameters is a rule of thumb, but that seems pretty excessive.

 

[pennpiper]

Read the following:

http://pipingdesigners.com/phpBB/viewtopic.php?t=47

This question comes up at least every six months.
I don't remember finding a minimum requirement spelled out in any of the B31 Codes. However most Engineering Companies and most big Clients (Exxon-Mobil, etc) have their own Standards that address this. If you are currently on a project you should ask your Client Rep.

p.s.: what do you mean by "Tradesman"?

 

[kenmac777]

Thanks for the excellent link! I've never heard of that website.

I can't ask the client rep - I am the client.

Tradesman is a Canadian term for a journeyman who belongs to an indentured trade such as welding or pipefitting.

 

[Gapinspect]

Depending on the size of the pipe,I have seen anywhere from 2 x Diameter for small (under 6") pipe/tube or down to 6" on large diameter pipe. The codes don't specify a minumum distance but good engineering and welding practices do. Most clients (all Canadian) that I work with have a standard of 2xD for all sizes.

I would say that your tradesman is in the ball park.

 

[MJCronin]

Pennpiper,

You are absolutely WRONG..!!! This question comes up about every three months.

Everything eeryone says above is correct, the pipin codes do not address this, some companies have thier own policies.

I believe it comes down to the inspectability of the welds and the possible affects of the "Heat Affected Zone" (HAZ) between the two welds (depending on the materials).

I have seen two buttwelds on small bore CS piping which were 3" apart (no HAZ) that were perfectly acceptable to everyone.

My opinion only...

-MJC