Grade 316 stainless steel

Grade 316 stainless steel is the marine-grade austenitic stainless: 2 to 3% molybdenum added to the base 304 chemistry, giving significantly better resistance to chlorides and salt corrosion. It is the specified grade for coastal fixings, pool surrounds, and saline-soil applications. The premium over 304 runs 30 to 50% on equivalent fittings, generally cheap insurance on a coastal job.

Where 316 is required

Coastal locations within 1 km of breaking surf (and routinely further inland for direct salt-spray exposure).
Pool surrounds and pool fencing (chlorinated air, splash zone).
Indoor swimming pool halls, spa rooms, and aquatic centres, where chlorine atmosphere is more aggressive than open-air coastal use.
Saline-soil sites (some coastal-plain and saline-affected agricultural regions).
Termite barriers (e.g. TermiMesh) where the AS 3660.1 stainless-mesh provision requires marine-grade chloride resistance.

316 vs 316L

316: standard chromium-nickel-molybdenum composition.
316L: low-carbon variant (≤ 0.03% C vs ≤ 0.08% for 316). Better weldability, less susceptible to inter-granular corrosion at the welded zone. The default for welded marine work; sometimes specified for fixings too.

For non-welded fixings (bolts, hinges, brackets), 316 and 316L are functionally equivalent in service.

Identifying 316

A4 on fasteners (DIN/ISO) = 316.
Stamped “316” or “316L” on the product.
Visual alone won’t distinguish from 304; rely on the marking and docket.

For a builder

Coastal default is 316. The box premium pays for itself the first hinge you’d otherwise replace.
Pool surrounds: always 316. Indoor or outdoor.
Don’t accept “318” substitutes. 318 is a different grade. If spec says 316, only 316L is an acceptable swap.

Category: Materials / metals.

Where 316 is required

316 vs 316L

Identifying 316

For a builder

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