Debasis Please be specific about material, the process in which it is in service, thickness of material used, welding process and weld joint design employed. Your question is too general in nature. C.V.Srinivasan Nishi Engineers Pvt Ltd India June 12,2006 E-mail: nishi@vsnl.com >In practical field u/ maintenance perspective PWHT often >becomes very difficult and often impractical too. It has >been realised that aby employing a specific welding >technique called " TEMPER BEAD WELDING " or " THREE >LAYERED CONTROLLED DEPOSITION PROCESS" the PWHT can be >avoided. > >Any one having experience in this very application of >welding process or cases where the PWHT in Filed maintenance >has been avoided . > >regards >DM

Debasis You are aware that both P 11. P 22 are both air hardeneing grades. You are also aware : In hydro carbon service, to my mind it appears that it is far too adventurous for a process, maitnanacne / inspection persons to think of waiving a PWHT just because it is inconvenient or difficult to do at field joints. You will soon recognize that you will have to pay the penalty at a later date with catastrophic failure consequences or major fire hazards if you suggest a short term solution to avoid one problem of field PWHT in time for such ari hardeneing grade / dangerous materials. For steam service, some possibility of Caustic SCC is likely . If it SSH (super heated steam service) you have to do think of relieving by PWHT. As an intermittent emergency step for extreme urgency, you could think of doing at a lower temp say 550-600 deg cent and longer time to alleviate the problem of PWHT. For frequent stop and re-start of welding process in such materials, you have to receognize the fact that you will be unknowingly creating more internal stresses in these materials by not doing straight PWHT. If it is an academic question, to temporarily satisfy a maintenance person's unwillingness to do a PWHT, for s hort duration operation run you can do an emergency intermediate temp holding, then intermediate S.R at lower temp would give some answer till a major shut down when the joints can be properly PWHT. If you think you can by-pass a PWHT on air hardening grades just because a plant maintenance person is unwilling to do, process upsets or process variables will ultimately show the effect in catastrophic failures - due to such lop sided view to by-pass PWHT for these materials. World over plants - if you go through case histories of failures in some of the problems faced in P 11, P 22 materials usage, who have by-passed the conventional PWHT in these materials have suffered huge material/ process loss and in some cases huge fire related damage to plants. Enough case histories have been published on these to warn of consequences to a plant user and wantonly contemplating a by-pass to carry PWHT in using theee materials. Question : Would you like to be wiser from experiences of others or would you like to burn yourself by suggesting things which will play havoc for the life a plant or material - please address this question to you / plant maintenance people. Trust this is of help to you. C.V.Srinivasan Nishi Engineers Pvt Ltd India June 13, 2006 E-mail: nishi@vsnl.com >for P11, P22 material in hydrocarbon or steam service.