The results of a 3 year study of the corrosion performance of welded panels of four types of stainless steel in three atmospheric environments are presented. The alloys chosen were weldable grades used in process industriesfor fabrication of plant for exterior applications such as tankage, pipework, and processing equipment. The grades were AISI types 304L and 316L (austenitic), AISI type 444 (ferritic), and proprietary grade 3RE60 (duplex). The panels were welded with austenitic filler metals and three surface finishes were employed: ground, polished, and pickled. The three environments chosenfor the exposure sites were severe marine, urban–marine, and a geothermal atmosphere.