Udayan Patel Sour content definition varies from refinery to refinery depends on crude oil used. You have not specified the H2S content in your refinery operation. If it is carbon steel, probably YES. You can avoid PWHT with qualification to check hardness of completed weld < 200 BHN. If it is low or medium alloy steel, probably NO. You may have to do PWHT of socket weld joints (even if you are assured of a weld with hardness < 200 BHN both durign qualification needs and also as per joint design and joint welding completion hardness check). Socket welds in sour service in alloy service - with outside hardness measurements showing < 200 BHN is no guarantee that the inside socket weld has hardness < 200 BHN. Joint may still have some higheer hardness than permitted by NACE MR 0103 -2005 (previous MR 0175 - 2003). Since criticality of cracking may differ with joint design and the type of crude being refined, it is worth as a possible precaution to carry out PWHT of socket welds of low alloy or medium alloy steel used in refinery service. Delayed cracks are known to develop after some years in refinery service in low alloy or medium alloy steel when declared welds were known to have < 200 BHN from outside socket weld hardness check. Trust this is of help to you C.V.Srinivasan Nishi Engineers Pvt Ltd India March 14, 2006 E-mail: nishi@vsnl.com >Is it acceptable to have socket welds in sour service ( NACE >MR0103) without post weld heat treatment. Maximum hardness >will be limited to 200 BHN. > >Welding procedure will be qualified with 200 BH. However any >recommendations on welding is appreciated