Both are austenitic stainless steels. 316 contains molybdenum, so it resists chlorides and some acids better than 304. In practice that means salt air, pool water and chlorinated wash-down water. For dry indoor work, 304 does the job at a lower price.
| Where | Usual grade | Why |
|---|---|---|
| Dry indoor (offices, malls, lobbies) | 304 | No chlorides, so 316 adds cost without adding anything. |
| Outdoor, inland | 304 or 316 | 304 is common. We move to 316 if the area is washed often or the consultant asks for it. |
| Coast, pools, spas | 316 | Chlorides cause pitting and brown staining on 304. |
| Food plants with chlorinated wash-down | 316 | The Baladi poultry trenches were 316 for this reason. |
This is what we normally see on projects. Your specification and consultant have the final say.
In hot, high-chloride conditions (around 150 °C), 316 can still crack from stress corrosion. That kind of process environment needs a materials engineer to choose the alloy.
Finish affects how the part looks, how easy it is to clean and what it costs, so write it down:
Welding marks the finish and leaves heat tint. Tell us if you want welds ground flush and blended in. For parts that touch food, see the hygienic fabrication guide.
For example: “316L sheet, ASTM A240, 2 mm, 2B, EN 10204 3.1 certificate.” That covers grade, product standard, thickness, finish and certificate. If something is missing we have to come back to you with questions. Handrail tube is usually made to ASTM A554 (welded stainless tube). Certificate types are covered in the EN 10204 guide.
Answer a few questions and you get a list of what to attach, plus a summary you can send us straight away.
For dry inland work, 304 is widely used. Go to 316 near the coast, around pools, where the area is washed with chlorinated water, or when the consultant specifies it. Tell us where it's going and we'll advise.
Low carbon (0.03% maximum). Less carbon means less risk of corrosion at the welds, which is why 316L is common for welded work.
It resists rust thanks to a thin chromium oxide layer. Iron contamination, chlorides or a damaged surface can break that layer down.
No. Both are basically non-magnetic when annealed, and cold working can make either one slightly magnetic. Only the mill certificate or a PMI test tells you the grade.
Check the numbers against the current edition of each standard and your project spec.