Manthax You cannot conclude with water leaks it was only from tube side - hydrogen related damage. It could well be concentration of BFW from shell side to cause the problem in inconel 600 weld overlay. If you have experience in doing such repairs it is well and good.If you do not have experience in doing such repairs, suggest engage a good consultant well versed in this material and the types of attacks that had to be countered to solve this problem after repairs. I do not know from which place and which company you are writing. If some help is needed, please give full details in e-mail to me Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India Aug 01, 2008 E-mail: nishi@vsnl.com >Hi Shrinivas, >Thanks for the reply, this was very informativ,e you are >spot on, its the WHB at exit of ammonia convertor which is >one of the most interesting areas in most of the ammonia >designs. > >From the discussion, can this be concluded that the failure >are not because of corrosion from water side. We did >experience tube failures in same WHB due water chemisty >problems in UDHE design but this particular failure appears >(Topsoe) to be due to hydrogen. > >Would like to suggest any specific mesures to be taken for >its repair? We are right now repairing the defective welds, >after machining out the complete tube / tubesheet weld to >ensure removal of affected areas, we preheated the tubesheet >to remove any hydrogen. While welding back the tube to tube >sheet joint, we are facing problems porosity. Could you >please help. > >regards > > > >Kind regards, Manthax