My views on your proposed action plans are like this: From the description you had given, it appears that the affected portions to be buttered with Inconel may not be a large area.If that be the case, why to bring down the equipment, do the buttering at the ground, post weld heat treat and again re-erect the same. If you re-erect a tall column like CO2 Absorber, i am sure that you should recognize the attendant problem of verticality, deflection measurement, proper pipe supports, stress analysis of piping if alignment goes out of order during re-erection of the Absorber and all the other problems likely to crop up in service due to mis-match stresses in piping etc. In all probability, yuo may have to do hydro-test again to satisfy that the foundation and the supports are withstanding after the new re-erection of the tall column. You should take a set of correct verticality and deflection measuremnts now in operation before dis-mantlign the tower and compare the same after re-commissioning the second time erected column like CO2 Absorber. For all that the original verticality, deflection measuremtns may not match at all. I am sure that you would like to review from these angles before a decision is taken to dis-mantle a well set CO2 Absorber - in foundation, with verticality, deflection and piping stresses being minimum now. This absorber as i could read from yout description has deveoped local corrosion -erosion patterns on the shell at some elevations where tray collapse had occured and un-even flow of CO2 rich hydrogen had eroded due to inhibitor flow not being uniform. Buttering after the inital Inconel to avoid post weld heat treatment with lining and thus weld S.S to Inconel or S.S to S.S : OK but this can be done in-situ as well currently without dis-mantling and bringign the huge column down and re-erect the same with other problems likely to crop up. Actually you may not save effectively - both from cost wise and time wise by doing this twice -now tith butteringa nd post weld heat-treatment and later with lining and welding the lining after a yar or two in service. Also Inconel weld buttering will cost more than S.S. 310 or S.S. 309 except that dilution is fully taken care in Inconel. Trust this is of help to you. If you need any help for actual doing, please let me know. I would be available as a consultant on chargeable basis. C.V.Srinivasan Nishi Engineers Pvt Ltd Chennai 20 India June 04 e-mail: nishi@vsnl.com >Thanks again for your reply. > >I need your comments on following : > >" We have changed our plan We are going for partial >buttering of shell with inconel and after post weld heat >treatment we will install the column at its location. Then >based on future corrosion results on carbon steel we will >weld lining on the buttered portion. (weld will be made with >lining and buttered portion only not with Carbon steel >shell)Buttered porion will help to avoid stress relieving of >this column as we avoid heating of carbon steel beneath. >This way we are actually saving cost of initial weld >overlay or complete lining.PLease note that we will not >going to butter the complete shell only those portion will >be buttered with Inconel where Stainless Stell lining weld >will be made i.e. based on lining sheet sizes." > >Adnan >Sindh, Pakistan