If the vessel is integral clad S.S. 316 L , there should be no major problem for the carbon steel base stength giving material from HIC if PWHT is already contemplated by designer and fabricator of vessel. PWHT should take care of major problems, if any likely, from HIC after some years. Generally, after PWHT, hardenss shuold be lower than Rc 20. If hardness record is maintaine of the different welds before start up of the plant and amine absorber to take a profile of hardness it shuold help you. Since temperature of operation in amine absorber are much lower inspite of higher pressure in Hydro crackers, if proper PWHT had been done and profiel record of hardeness is kept from beginning, this will help. Hardenss level after S.R (PWHT) in clad S.S. 316 L portion should be max: of 160-180 BHN ( Rc 18 or even lower ) and in the HAZ should be definitely lower than Rc 20 (around 190-210 BHN). C.V.Srinivasan March 27, 2004 India