Luis See reply for this separately in another message you have posted C.V.Srinivasan Nishi Engineers pvt ltd India March 25, 2008 E-mail: nishi@vsnl.com > >After making 100% TOFD to the welds of a propane sphere >there were detected liner discontinuities such as localized >cracks in the welds link of the dome to shell buds at >several deep thickness (plates thickness 40mm). > >After this first inspection the defects were mechanically >removed and the remaining thicknesses were controlled by UT > >The crack repairs have been done through filler welding at a >controlled temperature and 100% UT control and magnetoscopy > >The sphere was then submitted to a PWHT at 620%C2ºC during 2 >hours following by slow cooling. > >After PWHT, the sphere was again submitted to 100% of UT and >magnetoscopy and there has been found new defects in zones >out of the repaired ones. > >These defects have also been removed and after being >repaired they originate new defects in adjacent zones. > >After metallographic replicas we found intergranular micro >cracks > >Now we are going to repair all the indications given by >TOFD, even the ones which can be accepted by the codes. > >We thing that the defects found have been induced by atomic >hydrogen which is now molecular hydrogen arrested inside the >micro voids, so we need to have the steel as much clean as >possible to avoid more defects induction. > >Please Share > > >Luis Marques >