Welding Spacing in Pipe Spool
Welding Spacing in Pipe Spool
(OP)
I need to make a pipe spool with an 8" Sch 40 A-106 GR. B and two welding neck flanges A-105 Class 300 and I need to know the minimum spacing for the welds of the flanges, so as to make the spool as small as possible.





RE: Welding Spacing in Pipe Spool
Or do you just need a really short spool?
I've made 'em as short as 11mm overall length. No welding involved, just a piece of plate, faced, bored, and turned with an o.d. to fit just inside the bolt pattern, and a radial hole for a pressure tap. Like a thick gasket, made of metal.
Mike Halloran
NOT speaking for
DeAngelo Marine Exhaust Inc.
Ft. Lauderdale, FL, USA
RE: Welding Spacing in Pipe Spool
RE: Welding Spacing in Pipe Spool
RE: Welding Spacing in Pipe Spool
Really I am concerned with the allowable spacing between adjacent welds, because the spools have to be a given length, the flanges have to be WN and the welds of the flanges are resulting 78 mm apart.
RE: Welding Spacing in Pipe Spool
RE: Welding Spacing in Pipe Spool
RE: Welding Spacing in Pipe Spool
RE: Welding Spacing in Pipe Spool
I'm no welding expert, but I think the trick used was to make the first weld to a longer piece of pipe, then cut the pipe to length, then weld the second flange on. That way you get a "normal" heat pattern in both welds as there's more material to carry the heat away.
I'm sure there's a metallurgist out there cringing because there would be two heat affected zones very close to each other if not overlapping, but if we're talking 150# flanges, you're probably in business.
Good luck
Greg
RE: Welding Spacing in Pipe Spool
RE: Welding Spacing in Pipe Spool
I see that there is no clear definition on this subject.
I have been looking at ANSI B31.3 and there is no reference about this.
Someone mentioned that in ASME SEC VIII DIV 1, UW-14 you were allowed weld-on-weld connections. Can anyone check this for me as I don't have the code?
MickMc,
From where did you obtain the information of twice the wall thickness or 50mm minimum?
RE: Welding Spacing in Pipe Spool
It may not seem like a problem with the 8" connections that you state, but if the spool is to go between two valves then you may have difficulty getting the bolting in and out, the stud bolts required are 111mm long.
If the spool is to be removed regularly, you may want to include jacking bolts.
Another consideration may be to make the spool piece long enough so that you can replace it with a valve in the future.
Further, the smallest separation that could be obtained would be with a spectacle blind (cannot find my sheet with the dimensions).
RE: Welding Spacing in Pipe Spool
4.6.3.5 Spacing
Longitudinal seams on adjacent pipes shall be separated by at least 45 degrees of rotation or 150mm, whichever is the less. Circumferential welds shall be separated by at least 4 times the nominal pipe wall thickness (toe to toe). Attachments shall be at least 2 times the nominal pipe thickness or 40mm (toe to toe) from any weld, whichever is the smaller.
RE: Welding Spacing in Pipe Spool
The 40mm you quote agrees with BS2633 (Class 1 Welding)We tend to opt for 50mm between toes of the welds on our site.
RE: Welding Spacing in Pipe Spool
May be also testing the hardness of the welds, could give another assurance. A fitting manufacturer recommended a Brinell Hardness not more than 215 for the circumferential welds.
RE: Welding Spacing in Pipe Spool