Dear MartyS, It looks that the manufacture of the sink is without the drain hole and U did the stamping out punch to prepare the drain hole. To mention the process of stamping out the drain hole ( usually cold stamping) depending upon the material composition and thickness and supply condition will intrduce reasonable amount of stress with the peak at the free cut edges. And if the cut edge is left as-it-is it is v.much susceptible to produce Stress Corrosion and w.r.t. nature of stress boundary it can have cracks radiations. U have to take out the sink from the system --> clean/pickle and passivate the cut edge from all rusts --> if there is any sharp corner round it & ensure no sharp free edge --> do a good solution annealing heat treatment ( consult your Inspection dept to address specific solution anneal temp. w.r.t. your 304 grade ) --> Re-Pickle/ passivate the sink --> Use and monitor. Hope this will solve ur headache. regards and intimate. >Please Help. >I am having deep drawn 304 sinks made in China. The >material itself seems to pass tough salt spray tests w/o any >problems, but at the bottom of the sink, where we stamp out >a drain hole, rust forms on the cut edge, and the sink >therefore fails salt tests. Is this a result of the >stamping-cut process? What can we do to avoid this? >We urgently need advise and will be forever gratful for >help. > >MartyS