Walk through almost any food factory and the surfaces you touch are stainless steel. The two grades you will hear quoted are 304 and 316. Both are austenitic (non-magnetic) stainless steels and both are used for food contact, but they are not interchangeable. The choice comes down to what the surface will meet: plain water and mild food, or salt, acid and aggressive cleaning chemicals.
What the grades are made of
304 is the classic “18/8” steel: about 18% chromium and 8% nickel, which gives it good corrosion resistance and formability at a reasonable cost. 316 keeps the chromium and nickel but adds roughly 2–3% molybdenum. That single addition is what earns 316 its reputation for resisting pitting and crevice corrosion in chloride-rich and acidic environments.
Corrosion resistance compared
| Property | 304 | 316 |
|---|---|---|
| General food-duty corrosion | Good | Good |
| Resistance to chlorides (salt, brine) | Moderate | Strong |
| Resistance to acids (tomato, citrus, vinegar) | Moderate | Better |
| Cost | Lower | Higher (nickel + molybdenum) |
| Weldability / fabrication | Excellent | Excellent |
Where 304 is enough
For dry or mildly wet duty — flour handling, most cutting and conveying, and general frames — 304 is the sensible default and the most common food-grade choice. Many standard machines such as the SU304 temperature-control batch fryer are built on 304 stainless for exactly this reason.
Where 316 earns its cost
Specify 316 (or at least 316 for the wetted parts) when the surface meets salt brines, cured or pickled meats, tomato or citrus products, dairy, or frequent cleaning with chloride-containing agents. Pitting that starts in a crevice on a 304 part is slow to appear but expensive to fix; 316 delays it substantially. For a frying line the oil-contact and brine-adjacent parts are the ones to review first.
What to ask your supplier
Do not accept a verbal “it’s food-grade stainless.” Ask for the material grade of each wetted part and a mill test report (often referenced as an EN 10204 3.1 certificate) that states the actual chemistry. Knowing whether a part is 304 or 316 — and only on the surfaces that matter — lets you trade cost against the real corrosion risk of your recipe.
Frequently asked questions
Is 316 always better than 304 for food? Better at resisting salt and acid, yes — but not always the right buy. For dry or mildly wet duty 304 is perfectly food-safe and cheaper. Reserve 316 for wetted parts that meet brine, acid or aggressive cleaners.
Can I tell 304 and 316 apart by looking? Not reliably by eye. The grade should be confirmed by the material certificate and, where needed, a positive-material-identification (PMI) check on site. Do not specify by color or shine alone.
Does the whole machine need to be 316? Usually no. A common, cost-effective approach is 304 structure with 316 only on the wetted parts that actually meet corrosive product or cleaning chemicals.
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