When the product itself is the corrosive — fertiliser, salt, brine-washed vegetables — the bearing has to be 316 and the frame has to accept a bigger one. Conveyors & Bulk Handling duty is slow speed, abrasive dust and frame misalignment; the material is what decides whether the bearing survives it.
| Industry duty | slow rotation under steady belt pull, with abrasive dust at the load point |
|---|---|
| Typical media | abrasive dust, fines, washdown water |
| Housing temperature | −20 to +90 °C |
| Material and grade | 316 austenitic stainless steel |
| Hardness | 25–30 HRC |
| Temperature ceiling | 300 °C |
| Corrosion / chemical | seawater and most acids; no rust film |
| Relative cost | ≈4× of a standard 52100 bearing |
Fertiliser dust plus humidity is a saturated chloride environment, and salt handling is worse. 440C pits at the grain boundaries and the pits become fatigue origins within months. 316 has the molybdenum to resist that, and the price is hardness: the raceway is soft, the load rating halves, and 316 on 316 galls unless a dissimilar material is introduced.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Fertiliser conveyor pulley | Ball bearing unit | 316 insert, PTFE cage, 2RS | Nitrate and chloride dust; stainless avoids pitting at the seal lip. |
| Salt handling roller | Deep groove ball | 316 rings, Si3N4 balls | Hybrid restores capacity and stops fretting corrosion. |
| Brine flume conveyor | Ball bearing unit | 316 housing and insert | Whole assembly stainless, so no galvanic pair in the wet zone. |
| Material | Fit here | Choose it when |
|---|---|---|
| 316 | Best fit | Constant chlorides from the product, where 440C would pit. |
| 440C | Workable alternative | Fresh-water washdown only — twice the capacity at a third of the price. |
| POM | Workable alternative | Light rollers where metal contamination of the product is unacceptable. |
No. It resists pitting but the soft raceway wears, and abrasive fertiliser dust still gets through the seal. It lasts longer than 440C, not forever.
Austenitic stainless work-hardens and cold-welds to itself under contact pressure. A ceramic ball or a polymer cage breaks the metal-to-metal pair.
Usually yes. A 316 bearing on a chrome steel shaft creates a galvanic couple at the fit, and the shaft corrodes under the ring.
Hardness, temperature, corrosion and equivalents for 316 stainless.
Read →Typical duty, recommended types and suffixes for conveyors.
Read →Head & tail pulleys — head and tail pulley bearings and idler positions in bulk handling.
Read →Washdown food conveyors — food-grade conveyors cleaned with water and caustic every shift.
Read →Send the position, bore size, quantity and the medium it sees. We reply with the material certificate, clearance class, lubricant and price within 30 minutes on working days.