Post Weld Heat Treatment
Post Weld Heat Treatment
(OP)
we need to install (asap!) a tee connection. however, the tee welds will require pwht (as the thickness is 25.4mm) but we don't have the time as the plant shutdown cannot be extended.
what we did is that we tapered the ends of the tee connection (three ends) to a thickness where pwht will not be needed and proceeded with the weld connection. needless to say, we did not do any pwht on the three welds.
is the tapering of the thickness to forego the pwht allowed? with the tapered butt ends of the tee, the heat affected zone (haz) is thus reduced to a thickness where pwht is no longer needed. am i correct on this haz?
is there a code or a standard that says so? is this good engineering practice? what might be the consequences of our action?
our design pressure is 2.14 mpag while design temperature is 216degC. the tee size is 30-inch diameter with a wall thickness of 25.4mm.
what we did is that we tapered the ends of the tee connection (three ends) to a thickness where pwht will not be needed and proceeded with the weld connection. needless to say, we did not do any pwht on the three welds.
is the tapering of the thickness to forego the pwht allowed? with the tapered butt ends of the tee, the heat affected zone (haz) is thus reduced to a thickness where pwht is no longer needed. am i correct on this haz?
is there a code or a standard that says so? is this good engineering practice? what might be the consequences of our action?
our design pressure is 2.14 mpag while design temperature is 216degC. the tee size is 30-inch diameter with a wall thickness of 25.4mm.





RE: Post Weld Heat Treatment
What's the remaining wall thickness after the taper?
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RE: Post Weld Heat Treatment
sir, the resulting tapered thickness was at an average of 12.5mm while the legnth of the taper was approximately 50mm from butt ends.
thank you very much indeed sir.
RE: Post Weld Heat Treatment
At the moment, you appear to have an unknown risk of failure.
Regards,
athomas236
RE: Post Weld Heat Treatment
http://virtualpipeline.spaces.msn.com
"What gets us into trouble is not what we don't know, its what we know for sure" - Mark Twain
RE: Post Weld Heat Treatment
sir athomas236, indeed we should have done that and this. but the short notice we got on the plant shutdown and a short duration at that, we didn't have much choice but to use the available tee. thank you anyway. we do have an unknown risk of failure.
comments, advices, are very much welcome, negative or positive. feel free please. again, thank you very much.
RE: Post Weld Heat Treatment
If your connection is in carbon steel and the reduction of the thickness in the ends of your tee, withstands the maximum allowble operation service pressure of your system I think the pwht can be avoided taking in mind that the reduction in thickness of the tee should be as smooth as possible till reaching the thickness of connection pipes
regards
luismarques