To meet new U.S. Environmental regulations, the Valdez Marine Terminal is being equipped with a marine vapour system to control hydrocarbon emissions during loading of crude oil onto marine tanker vessels. Long term corrosion resistance of piping and equipment was a key objective for the project. The process conditions within the vapour system includes corrosive liquid condensate that is highly acidic and contains high levels of chlorides. Corrosion resistant alloys, including duplex stainless steels, were selected for piping and equipment. The factors influencing material selection, design, manufacture, and construction are presented here with particular attention to the areas involving duplex stainless steels.