Welding of tread joints
Welding of tread joints
(OP)
A customer has requested the welding of a 3/4" threaded nipple into an SA 105 Sec. VIII-1 coupling nozzle. I seem to remember a Code provision that allowed this if all of exposed threads were "consumed" in the fillet weld. Where might I find this provision.





RE: Welding of tread joints
There is no such statement in the the Code and furthermore, I would recommend against it. Threaded joints are designed as such and seal welding them is poor engineering practice.
RE: Welding of tread joints
RE: Welding of tread joints
provided the work you are going to perform is to seal weld a threaded joint on a piping system the code provision you are looking for is:
ASME B31.3 (2006) Par. 328.5.3
Seal welds shall cover all exposed threads
or respectively
ASME B31.1 (2004) Par. 127.4.5
Where seal welding of threaded joints is performed, threads shall be entirely covered by the seal weld.
However, seal welds may be used only to prevent leakage of threaded joints and shall not be considered as contributing any strength to the joints. Since you talked about a "fillet weld" and "consuming threads" I still wonder whether I understood your question correctly.
RE: Welding of tread joints
RE: Welding of tread joints
This is only for sealing. The code does not allow any added strength to be assigned to the joint.
We commonly seal weld 2" NPT joints on temporary NG compression lines using 4000# hammer unions.
Big guys with big hammers can really loosen threaded joints!!
RE: Welding of tread joints