Inspector 1978 I would like to add on the comments of Debasis on this failure Considering the service, BFW at low temp on SS 304 L, permeabiity measurement will not reveal any characteristic changes on such tight SCC. Permeability measurement is somewhat useful test for high temperature service transformation expected in hydro cracking furnaces after porlonged exposures for several years. For this BFW service, such transformation will not occur (as such transformation occurs due to high tempeature service effect in hydro carbon furnaces at medium pressures associated with high temperatures of 800 deg centigrade or more) This failure of SS 304 L had occurred in BFW at low temp (50 deg cent) and low to medium pressures. Hence S S 304 L will not reveal permeability changes. For a static equipment with built-in nozzle (WN flange) to code design prractices, you do not expect any vibration for normal standard piping thickness with WN flange just designed and installed at the shell exit. Fatigue related effect will not be there for such equipment / nozzle to flange joints. Hope this helps you to analyze your failure from possible mode with proper diagnostic investigation possibilities. C.V.Srinivasan Nishi Engineers Pvt Ltd India July 3, 2010 E mail: nishi@vsnl.com >Dear Inspector 1978 >with compliments to Mr. Srinivasan.... >(1) Pl. tell your failure analyst vendor to identify whether >the twins which they have reported in the flange parent >metal are mechanical twins or annealing twins. >(2) You may check for a profile across and along the crack >upto both nozzle and flange parent metal for the degree of >magnetism by using a permeability meter or a simple small >magnet. If it is properly solution annealed magnetism will >be very negligible. >(3) Also as advised by Mr. Srinivasan microhardness proiling >also reqd. > >(4) As you could not find the crack by WFDP it appears to be >a very tight and fine crack. as such you may also check for >any associated vibration ( fatigue condition) to the >nozzle/flange system > >Pl. keep on posting for any analysis development. > >>Dear Mr Srinivasan >> >>Thank you very much for your reply.We will surely go for >>Micro Hardness as suggested by you to establish the mode of >>failure, >> >>Regards

Dear Mr Srinivasan Thank you very much for the inputs.We hava already dispatched the flange for further failure analysis. I will keep updating for your valuable comments. Regards