Weld intersection circ weld and o-let weld

Date 10-28-2010 00:19

I thought 31.3 addressed this, but I can't seem to find it anywhere. Do any of you know if 31.3 allows the placement of an olet fitting (and thus a penetration into the pipe) directly on top (through) of a circumferential weld?

Thanks
Justin

By MBSims

Date 10-30-2010 03:16

I don't know of any requirement that prohibits it, but it can cause problems where the operating temperatures are in the creep range. I've seen headers with tube holes drilled through the girth welds that suffered massive creep damage and failure. Sometimes you can't avoid doing it though. Probably not a big issue if placed in a low stress area. I have seen weldolets with a pipe cap placed over leaks as a temporary measure until the weld could be repaired during a scheduled outage.

By js55

Date 11-01-2010 12:46

MArty,
Do you have any idea as to the cause of the creep damage?
The reason I ask of course is that circumferentials obviously cross over longitudinals all of the time which, which would of course create the same heat regime histories as a weld-o-let on a corcumferential. If there is no creep damage history similar to what you speak of it would lend itself to the argument that its not a welding metallurgy issue but something else.

By joe pirie (***)

Date 11-01-2010 06:40

great trick works real good , have'nt seen it done in a while. i don't think to many youngsters have ever
seen or heard of it but it saved my ass on several occasions. lol

By scrappywelds (***)

Date 10-30-2010 01:31

same here seen it and I have personally put them in doesn't mean it is right.

By scrappywelds (***)

Date 10-31-2010 01:09

I would say it doesn't address it but since window welds are done all the time under section 1 in the boiler.