Customers ask us this every week, usually while comparing two quotes. The honest answer is that most jobs run fine on 304 — and the ones that do not, fail fast on it.
The only difference that matters
316 contains 2–3% molybdenum. 304 contains none. Everything else about the two grades is close enough that you will not feel it in fabrication.
Molybdenum is what resists pitting from chlorides — salt in coastal air, chlorinated water, seawater, many process chemicals, and the chloride in some cleaning agents. Chromium alone builds the passive film; molybdenum keeps chloride from punching holes through it.
When 304 is the right call
- Indoor railings, furniture, kitchen equipment, panelling
- Structural work more than 15–20 km inland
- Food contact where the wash-down is water and mild detergent
- Anything where the surface gets cleaned regularly
When to pay for 316
- Within a few kilometres of the sea, or in permanent salt spray
- Swimming pools and water treatment plant — chlorinated water is unforgiving
- Dairy, brewing and pharma process lines that are CIP-cleaned with acid or caustic
- Chemical plant, effluent handling, fertiliser storage
- Fasteners and fittings that will sit wet and cannot be inspected later
The trap: mixing grades
A 316 handrail bolted with 304 fasteners will fail at the fasteners. Small components are cheap compared with the labour of replacing them, so match the grade of the weakest part to the environment, not to the budget.
A word on 304L and 316L
The "L" is low carbon. It matters when you weld thick sections and cannot solution-anneal afterwards — low carbon prevents chromium carbide forming at the grain boundaries, which is what causes weld decay. For sheet work under 3 mm it rarely makes a practical difference, and most mills now supply dual-certified 304/304L anyway.
Rule of thumb we use at the counter: if the part will be wet with anything other than clean water, quote 316. If it will be dry or rinsed, 304 is enough.
Not sure? Send us the application and the location on WhatsApp — we would rather talk you into the cheaper grade than sell you the wrong one.
