Both grades are austenitic stainless steels with excellent general corrosion resistance, but grade 316 contains 2–3% molybdenum which substantially improves resistance to chloride ions — the principal cause of pitting corrosion in stainless steel. In practical terms, grade 304 is adequate for most dry internal applications and sheltered external environments away from the coast. Grade 316 is the correct specification for any external application, coastal location, swimming pool surround (however Duplex is an even more resilient grade of stainless for this environment), marine environment or environment with regular cleaning using chlorinated chemicals.
F.H.Brundle’s Pro-Railing components are manufactured in grades 304 and 316 with some available in Duplex 2205.
