Adjacent weld distance requirements in ASME

Date 02-29-2008 08:18

We're seeing lots of adjacent welds which are very close to each other like the fillet welds of the reinforcing branch connection which are very close to the seam of the pipe spool for materials like stainless steel and LTCS(ERW and SAW to name a few). Our Project specifications calls for 3 times the thickness of base metal the distance or close proximity between welds. Is there any specific requirements in ASME like in B31.3 with regards to this subject? What normally the effects to the materials if the adjacent welds are very close to each other. What exactly the reason behind why we are not allowing these practice in building a LNG Plant?

By CWI555

Date 02-29-2008 12:03

There are no specific requirments in B31.3 for this. It's going to kick you back to design calcs for that. As for what normally effects.. normal doesn't come into the picture for LNG or any other cryogenic service. 3x base metal prohibition sounds like a stress analysis. B31.3 puts the monkey on design engineering, who has to provide this information to welding engineering who in turn has to see to it that it finds it's way to the WPS.

B31.3:2004
328.4.3 Alignment
(a) Circumferential Welds
(1) Inside surfaces of components at ends to be
joined in girth or miter groove welds ""shall be aligned
within the dimensional limits in the WPS and the engineering
design.""
(2) If the external surfaces of the components are
not aligned, the weld shall be tapered between them.
(b) Longitudinal Welds. Alignment of longitudinal
groove welds (not made in accordance with a standard
listed in Table A-1 or Table 326.1) shall conform to the
requirements of para. 328.4.3(a).

Regards,
Gerald

By jon20013 (*****)

Date 02-29-2008 12:28

I've seen minimum distance requirements many times throughout the years but to the best of my memory (which isn't great) they've all been subjects of project specifications. The "really should be" some guidance in the codes and I'd be very surprized if one of our Code experts doesn't pull a bunny out of his or her hat! ;-)

By CWI555

Date 02-29-2008 14:27

There is no bunny to pull out of a hat on b31.3. As said, that particular code puts that monkey on design engineering.