What testing can be performed to determine if liquid metal embrittlement has occurred? We have a 304 stainless steel tank to which the contractor has welded galvanized steel stair treads. API 650 Appendix S prohibits such welding but nonetheless it has happened. The contractor claims that all galvanizing was removed prior to welding but visual inspection has shown otherwise. How can we determine if a problem exists at each stair tread before getting involved in extensive tank repairs. Thanks for your help.

rbalaw Liquid metal embrittlement is to be determined by micro of areas affected. Since this is API 650 constructed tank with Carbon steel shell material welded as a non-pressure attachment with a G.I Structural stair case angle or trusses (fillet weld only of an angle or truss) from external side (i.e, out side attachment of fillet weld) - LME chances are most un-likely unless structural component forms a part of the main shell welds. Attachment welds do not form a part of pressure component in any structural welding. Since this is structural welding done for external stair case as a non-pressure attachment, depth of penetration will not be deep to worry you from LME problem. This is my view. LME problem will be pronounced in SS component when Zn or Cd from galvanized steel penetrates due to negligence of not removing the coating around HAZ or parent while welding dissimilar SS with galvanized steel component or with Zn rich paint not removed from pipe line when welding is done for SS components. This fillet weld depth may at best be restricted to first 1- 2 mm from out side. Chances that would affect your steel shell may not be high. However, in order to establish this: If you wish, you can do in-situ metallography at spots accessible heights for this and see if the depth of Zn or Cd coating penetration of Zn/ Cd in steel structure is severe during and after welding in the fillet weld to be checked. Second LME will create problems more for SS material with dissimilar Zn or Cd coated structural steel if it is in operation. Hope this helps C.V.Srinivasan Nishi Engineers Pvt Ltd India March 12, 2008 E-mail: nishi@vsnl.com >What testing can be performed to determine if liquid metal >embrittlement has occurred? We have a 304 stainless steel >tank to which the contractor has welded galvanized steel >stair treads. API 650 Appendix S prohibits such welding but >nonetheless it has happened. The contractor claims that all >galvanizing was removed prior to welding but visual >inspection has shown otherwise. How can we determine if a >problem exists at each stair tread before getting involved >in extensive tank repairs. > >Thanks for your help.

Thanks