Strength welds between tubes (mat. SA213GrT11) and tubesheet (SA336GrF11Cl2) will be locally PWHTed. My question is:
What about welds between transverse baffles to longitudinal baffle (h.e. TEMA type F), and welds between long. baffle and tubesheet - material also 1.25Cr-0.5Mo - is it required to perform PWHT?

thanks,
malyl.

refer Table UCS 56, else give more details like thickness involved clear joint configuration, design conditions etc.

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Raghuram

Dear Raghurambathula, all members,
More details: Exchanger type BFU, tubes 25.4mmx2.11, tubesheet thk 180mm, all baffles thk 10mm, tubes welded to tubesheet as per fig.UW-20.1(c).

regards,
malyl.

Malyl,
Why would you want to stress-relieve non-pressurized welds? Are they mechanically loaded? Can they break leading to a failure?

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Konrad Anikiel

Konrad,
Of course not. My concern is about pressure loaded tubesheet and areas of welded to it non-pressure parts (like sealing strips, guide rails). What will happen if I will not stress-relieve HAZ, tubesheet material, welds in the area of welded non-pressure parts to tubesheet?

regards,
malyl

Malyl, I see now. Can't they be welded prior to the tubesheet heat treatment so the whole thing will be HT'ed?

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Konrad Anikiel

Of course tube bundle can be ht'ed as a whole thing. But my question is: is it required (by the code) to pwht also welding areas of non-pressure parts welded to pressure bearing tubesheet or can I only pwht tube to tubesheet welds?

Malyl, my understanding of "...all welds in pressure vessels or pressure vessel parts shall be given a postweld heat treatment..." is that non-pressure to pressure details welds are within this requirement. There used to be UCS-56(d)(6) exemption, but it's not there anymore. Maybe someone here knows why?

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Konrad Anikiel