Food-grade stainless steel: grades and requirements
12Х18Н10Т is a food-grade grade, as are its analogues 304 and 321: it releases nothing extra into the product and withstands washing and disinfection. But the grade alone is not enough.
Food contact is determined by three conditions: a resistant grade, a smooth surface without stagnant zones and a correctly made weld seam. Rough grinding or scale on the seam will ruin even 316L, while a smooth 304 sheet will serve for years.
What "food-grade" means
"Food-grade" is not a separate grade and not a special heat. It is a set of requirements for the surface that contacts the product.
The requirements come down to four points:
- the material must not release metal ions into the product and must not react with it;
- the surface must be smooth and without pores, so that product residues are not retained in the micro-relief;
- the seams must be cleaned and passivated, without scale and overlaps;
- the design must not have dead ends and stagnant zones where product stagnates during washing.
These requirements are met by the austenitic grades 304, 304L, 316, 316L, 321 and their analogues. Ferritic 430 is suitable for dry zones, decorative panels and housings where there is no direct contact with a wet product and aggressive washing. The economy grade 201 is not intended for food contact: manganese replaces nickel only partially, and the resistance of such a grade to a wet environment is lower.
| Grade | Food contact | Strengths | Limitations |
|---|---|---|---|
| AISI 304 | Yes | Water, milk, dough, washing, steam | Not for salt, brines and chlorides |
| AISI 304L | Yes | Welded tanks without subsequent heat treatment | Lower strength than 304 |
| AISI 316 | Yes | Brines, sauces, salt solutions, chlorides | More expensive than 304 |
| AISI 316L | Yes | Welded lines with an aggressive environment | More expensive than 304 |
| AISI 321 | Yes | Units with heating and welding | Not for chlorides |
| 12Х18Н10Т | Yes | Analogue of 321, high-temperature units | Not for chlorides |
| AISI 430 | Dry zones | Panels, housings, décor | Not for wet product and washing |
| AISI 201 | No | Décor, household appliances | Not for food contact |
In practice the question "is 12Х18Н10Т food-grade or not" is decided not by the name but by the purpose of the unit. The same grade will suit a tank of hot water and will not suit a vat of salt solution, where molybdenum is needed.
Grades 304 and 316
304 is the working grade of food production. Tanks, tables, sinks, pipelines, conveyor belts and equipment housings are made from it. It withstands hot water, steam, organic acids, milk, beer, dough and most cleaning solutions.
316 adds molybdenum and gains resistance to chlorides. It is taken where there is salt: brines, salted meat and fish, sauces, cheese dairies, canning, and also in workshops with aggressive washing and in coastal areas.
| Parameter | AISI 304 | AISI 316 |
|---|---|---|
| Chromium | 18% | 16–18% |
| Nickel | 8–10% | 10–14% |
| Molybdenum | No | 2–3% |
| Food contact | Yes | Yes |
| Salt and brines | Do not use | Yes |
| Chlorinated water | Do not use | Limited |
| Washing and disinfection | Yes | Yes |
The difference shows in stagnant zones: under a gasket, in a weld seam, in a corner where brine accumulates. In such a place 304 becomes pitted within a matter of months, while 316L holds for years.
Food-grade stainless steel AISI 304 L differs from 304 by its low carbon content. This matters for welded structures: when ordinary 304 is welded, chromium binds into carbides along grain boundaries and the seam loses resistance. 304L has little carbon, so a welded tank does not require annealing after welding.
Surface requirements
The surface in a food workshop works no less than the grade. Smooth metal washes more easily, has fewer residues and fewer places for microflora to develop.
| Finish | Roughness | Where it is used | Features |
|---|---|---|---|
| 2B | Matte, smooth | Tanks, tables, panels | The mass option, washes well |
| BA | Light, after bright annealing | Tables, display cases, interior parts | Smoother than 2B, more expensive |
| №4 brushed | Decorative, with a directional pattern | Façades, housings, panels | Requires washing along the lines |
| Mirror, polished | Lowest roughness | Display cases, open zones, décor | Fingerprints show, care needed |
| Hot-rolled, industrial | Rough | Non-food units, structures | Not suitable for contact with product |
The order of surface requirements in food production: the closer to open product, the smoother the metal. The inner surface of a tank is 2B or polished, outer panels are brushed, and zones where the product does not touch the metal can be any industrial option.
A rough surface and welding scale are worse than the grade. Scale on a seam is a chromium-depleted layer that does not restore the passive film and additionally creates a relief for sticking. As a result, corrosion and contamination follow the seam, although the main surface stays clean. That is why after welding the seam is cleaned and passivated, not left "as is" in reliance on a good grade.
Where it is used
- Dairy and cheese production. Tanks, pasteurisers, cheese vats, pipelines. For brined cheeses and salt baths — 316L.
- Meat and fish. Tables, knives, salting vats, conveyor systems. Salt dictates 316L.
- Beverages and brewing. CCTs, pipelines, filling. 304 for water and beer, 316L for washing with aggressive solutions.
- Bread and confectionery. Dough mixers, tables, moulds, conveyors. 304 with a 2B finish.
- Catering. Kitchen tables, sinks, extractor hoods, dishes. 304 for contact with product, 430 for decorative panels.
- Warehouses and transport. Trays, trolleys, containers, frames. 304, and for salted products — 316L.
A separate word about purchasing. Food-grade stainless steel is not bought "by eye": the order states the grade, size, finish and purpose of the unit. If the unit works with salt, replacing 316L with 304 based on the appearance of the sheet is unacceptable — both grades look the same.
Frequently asked questions
Is 12Х18Н10Т food-grade or not
Yes, it is a food-grade grade. It does not release ions into the product and withstands washing. Its analogue is 321, not 304. It is not suitable for brines and chlorides.
Is AISI 304 food-grade or not
Yes, 304 is the main food-grade grade. It is suitable for water, milk, dough, washing and steam. For salt, brines and chlorinated water, 316 is needed.
Is AISI 201 stainless steel food-grade or not
It is not intended for food contact. It is taken for décor, housings and dry zones where there is no wet product and no aggressive washing.
Is AISI 430 food-grade or not
It is suitable for dry zones: panels, housings, decorative parts. It is not used for wet product and constant washing.
Which finish is needed for food-grade stainless steel
For contact with product — 2B, BA or polished. Rough grinding is not suitable: residues are retained in the relief.
Can 316 be replaced with 304 in a food workshop
If the unit works with salt, brine or chlorinated water, no. In other cases the replacement is possible, but the decision is made by the environment, not by the appearance of the sheet.
What to do with welding scale on a seam
Clean and passivate it. Scale is a chromium-depleted layer that becomes a corrosion centre.
How does 304L differ from 304
By its low carbon content. 304L does not lose resistance in the weld seam zone and does not require annealing after welding.
Place an order
Compare the grades in the breakdown AISI 304 or 316, choose a finish in the food-grade stainless steel section and check the thickness against stainless steel sheet. An order runs for one grade, one unit of quantity and one shipment week.