When do you desgin fillet weld or but weld

[Thuhuongengineer]

Hi everybody,
We have tubing welded socket (fillet weld) with coupling.
Coupling and tubing were material TP 316L, YS = 41 KSI, TS = 87 KSI.
Welding consumable is ER316L, YS = 390 MPA, TS = 550 MPA.
This joint will be hydrotest at 4200 PIS.
Normally,I know that Fillet weld are designed for piping under the pressure maximum 400 PSI So with this joint socket, I am worried about its design. How can I prove that the design of this joint guarantees the above pressure.

 

[stanweld]

Socket welds are routinely used at pressures well above 400 psi. Calculated thickness of pipe and coupling rating define acceptability of design.

 

[stanweld]

One caveat from the above. If service is in high cyclic service, butt welds would be recommended.

 

[nickelkid]

stanweld is right. If you have concerns of weld integrity a SW will not be able to be radiographed, a butt weld can. SW’s are cheaper and often are acceptable, but will only be able to be inspected via visual techniques.

 

[Thuhuongengineer]

Rating of Pipe and coupling have been designed at 6000 PSI. It mean that, this socket weld can be at pressure 4000 PSI when we carry out hydrotest.