Cooling water leakage at the turbine support leg, not at the welded joint, but along the vertical edge of the support. how can i repair this leak thru welding? what is the base material of this component?

 

khairulsulaiman,

Not a crack along the edge of the welded-on cooling water jacket?

Most of the aft support legs I've encountered on GE-design heavy duty gas turbine have all been "cut" from a single piece of metal, with a jacket welded on the outside face to which cooling water is piped. Most of the cracks I've seen occurred along the welded seam of the cooling water jacket/aft support leg interface.

Regardless, have you consulted the Parts List section of the Maintenance Manual provided with the unit? Usually, one can find a drawing of the aft support legs, and in the Notes on the first page of the drawing there is usually a reference to a welding specification, and in some cases there are even welding symbols on the drawing which a certified welder can interpret and understand.

You would do best to ask the packager of the turbine if they can provide you with more information.

Most often cracking of the cooling water jacket is related to one of two things: excessive heat caused by lack of cooling water supply, or improper treatment and/or maintenance of the cooling water fluid. But, I've never seen an aft support leg that was, itself, a welded assembly with the cooling water jacked welded on the outside face. I haven't seen every version and style, and with advancements in metallurgy in the past decade or so it's entirely possible that some packager of GE-design heavy duty gas turbines is, indeed, using welded assemblies. (You didn't tell us how old the unit in question is.) Still, it would seem there was either a lack of cooling water supply and/or excessive temperature(s) in the area of the aft support leg, or something amiss with the cooling water fluid.

Hope this helps!