Grade 316 stainless steel is the minimum for standard external UK environments. For coastal locations, pool surrounds, or any application involving regular exposure to saltwater or chlorinated water, Duplex 2205 stainless steel is the correct specification. Duplex 2205 offers approximately twice the strength of 316 and significantly better resistance to pitting and crevice corrosion. Grade 304 should only be used for fully internal, sheltered applications.
