A pressure vessel (tower) is being fabricated under the rules of ASME Sec. VIII/Div.1, including SA516-60N (thk. 18mm) for lower part and SA516-60N + Clad 316L (thk. 12 + 3mm Clad) for upper part . And the equipment service is lethal.
According to ASME Sec.VIII/Div.1 Part UW-2, post weld heat treatment(PWHT) is mandatory for Carbon Steel part. And according to ASME Sec. VIII/Div.1 Part UCL-34, PWHT is not recommended for Claded part

Question 1 : Is there any evidence in ASME Sec.VIII/Div.1 to necessitate PWHT for Claded part as well under the lethal service?
Question 2 : If the PWHT is done, what positive or negative impacts will be achieved?

mohammad hassan,
According to UCL-34, if base metal need to be PWHT, then the clad plate need too, but for ss 316l, the temperature of PWHT should be controled in any case that the physical properties and corrosion resistance of SS316 shouldn't be effected.