Dear Patel, For a maximum operating temperature 100C the selection of such hi-fi MOC like 762 or your cleat MOC is probably not convincing design or rather overdesigned. I would like to know from your designer why such upgraded MOC is applied ? Pl. let me know what WPS you have earlier followed ? Now, as you have observed cracks on Tube-to-cleat suport weld first check it with WFDP and gouge out all these. Also check the Tube areas. --> Take a stock of Hardness values --> If anyhow you get a higher hardness values over 22 HRc use a coil preheat of 150C --> Use a high Ni filer like INCO 625 or if not ER 310 by M.TIG process. --> Post weld WFDP --> wiser to do a Hydrotest to confirm. Hope this will be of some help. regards & Revert . D.Mitra Debasis.Mitra@hpl.co.in Inspection Dept. HPL