A marked Instance of severe pitting occurred recently in welded and cast stainless dyeing equipment. The action was highly localized at welds or in exposed porous spots in casings. Otherwise, the steel suffered no damage. The rusting was so severe after a couple of years that the equipment had to be thoroughly cleaned once a week to prevent discoloration of the fabric with rust and after four years many metal parts had to be replaced.
The dyeing process included a cycle of about half-hour scouring with detergents at 180 F followed by rinsing in fresh water before immersion in the hot fresh water dye bath. Up to this point there was no reason to anticipate serious corrosion. The actual dyeing operation ran for about 40 minutes, and during the last 20 minutes of this period 2 per cent rocksalt was added and the bath kept under agitation at 180 F....
