Pipe to Socket Weld Half Coupling

[llamatron]

I could use some help in selecting the proper weld joint type for a vessel we are building. Vessel is being built to ASME Section III, Subsection ND. The vessel has a drain pipe that ends in a socket weld half coupling. What is the proper joint type/configuration to join the pipe (1" Sch 80) to a 3000# SWHC (non-socket side). The IDs do not match so I already know I have to bore the pipe a bit to meet code requirements for mismatch and alignment.

Thanks for the help!

 

[Duwe6]

Why not cut the half-coupling off and install one on "frontwards", with the socket side facing the pipe? You cannot counterbore your pipe very much, or it is no longer the calculated, specified pipe schedule/thickness. Now you have to have this section redesigned and approved -- poor choice.

The weld that you would end up with without replacing your reversed SW Cplg will be a open-root butt-weld. The cplg will also need to be tapered to match the OD of the pipe to get it within the mismatch limits. By the time you get the redesign for the pipe, get the pipe counterbored, and get the cplg tapered, you could be done by replacing the problem. Plus, with the reduction of the pipe wall thickness and the reduction of the cplg thickness, you probably not meet the minimum design thickness anyway.

The best fitting to use for replacement is a SockO'let integrally reinforced fitting. Stronger and easier to install than a half-coupling. Bonney Forge is the original mfr of these, other fitting mfr's are now making these, and they are fairly available.

http://www.bonneyforge.com/products.php?pg=branch&subpg=sockolet

 

[trottiey]

I think I understand what llamatron means: the socketweld side is an open port facing the world, not facing toward the vessel. The NPS 1 pipe he's talking about is the nozzle going from the vessel to the socketweld port, not the external piping that hooks up to it. Am I right?

If so, then the obvious question becomes why not use a full coupling? But let's assume that some nuclear QA shenanigan has rejected all full couplings today - weird stuff happens in this industry.

You could taper the coupling and butt-weld as Duwe6 says, but you have other options that are probably easier: You could bore and make your own full-coupling. Or, you could bevel the pipe and make a full penetration corner joint.

A missing piece of information is the size of that SWHC - can I assume NPS 1? Knowing the ID dimension might help settle the details too.