316 vs 304 Stainless Steel for Marine Hardware
Start with the environment
Grade 316 contains molybdenum and generally offers better resistance to chloride-related localized corrosion than 304. Neither grade is immune to corrosion. Exposure, temperature, deposits and crevices affect performance.
What to include in a material inquiry
Describe whether the fitting is indoors, outdoors, near salt spray or continuously wet. Specify the required grade, surface finish, dimensions and quantity. If a drawing or purchase specification requires 304 or 316, state that explicitly instead of requesting only “stainless steel”.
Compare the complete specification
Ask the supplier to confirm the material designation and any documentation your project requires. Keep finish, dimensions and inspection requirements consistent when comparing quotations. Material grade alone does not establish the fitting’s load capacity or suitability for a particular assembly.
Before ordering
Provide the installation environment and mating components for review. Ask how the surface should be cleaned and maintained. For demanding chloride exposure or a safety-critical assembly, have the material and complete design reviewed for the actual conditions.
Technical reference: Outokumpu — Corrosion resistance