B31.3 Pipe Repair - Additonal Length
B31.3 Pipe Repair - Additonal Length
(OP)
I have a customer requesting to add to the length of pipe on a pipe structure, consisting of a 6" Sch. 40 pipe and two weld neck flanges welded to each end, for a piping system that we have already constructed. The 6" Sch. 40 pipe needs to grow by 1-7/8". The customer asked us to add the additional length by splicing the current pipe and welding an additional pipe to make the length, having an additional seam within the pipe. Is there a limit on the length the adder piece needs to be? Or can I just add the additional 1-7/8" length to the existing pipe? The pipe complies to B31.3.
Thanks!
Thanks!





RE: B31.3 Pipe Repair - Additonal Length
Regards
StoneCold
RE: B31.3 Pipe Repair - Additonal Length
A 6 inch dia 600 lb flange is 14.0 diameter with a 12 inch dia BCD drilled for 12 bolts. But - The 6 inch dia 600 lb flange IS 1-7/8 (1.875) thick.
Clearly, you cannot just substitute the higher-rated flange.
But - Don't bother welding up a new pipe and flange.
Machine (from compatible material standards to a 6 inch 150 lb flange!) a double-sided, double raised-faced, "blank" that is 1.875 (minus the second gasket thickness!) thick with a 6.062 hole through the center. Bolt it in place between the two flanges with extra long studs.
Design it and designate it for QA and registration purposes in the P&ID as an orifice/spacer plate with a full-sized bore.
RE: B31.3 Pipe Repair - Additonal Length
I would do the same!