An engineer was seriously burned when a thirty-nine inch expansion joint ruptured while workman were performing temporary repairs at a Texas refinery. The ruptured bellows spilled hot catalyst from a fluidizer catalytic cracking unit on the deck which the engineer had to cross to reach safety. The plaintiff alleged that the selection of Type 321 stainless steel by the process designer was unsound, and led to the rupture. O’Donnell was retained to establish why the bellows failed. We found that the stainless steel had not been heat-treated properly during the making of the steel itself and it was sensitized during fabrication and made susceptible to corrosive attack.