Failure of a Tank Coupling
Leakage was identified around a coupling welded into a stainless steel holding tank that stored condensate water with low impurity content. The tank and fitting were manufactured from type 304 stainless steel. The coupling joint consisted of an internal groove weld and an external fillet weld. Cracking was found to be apparent on the tank surface, adjacent to the coupling weld. Chlorine, carbon, and oxygen in addition to the base metal elements were revealed by energy-dispersive x-ray spectrometric analysis. A great number of secondary, branching cracks were evident in the weld, heat-affected zone, and base metal. The branching and...