Repair of Bellows Expansion Joints

A metal bellows expansion joint is a highly engineered, precisely manufactured piping system component. It cannot withstand mechanical abuse and perform its intended function without repair or replacement. A 304 stainless steel two-ply metal bellows expansion joint was intentionally damaged by drilling or grinding holes and grooves through the outer ply and subsequently weld-repaired by welding patches over the defects or by filling the grooves. In addition, gouges that did not penetrate the outer ply were blended to a smooth contour. This assembly was fatigue tested to demonstrate that when inadvertent damage does occur the bellows may be repaired. There are three methods of repair which may, under closely controlled circumstances, be a justifiable alternate to replacement of the bellows. Details of this testing program are described in this paper.