On a CIP-washed pump the bearing is usually killed by the wash, not by the fluid it is pumping. Pumps & Compressors duty is continuous running, thrust reversal and process fluid along the shaft; the material is what decides whether the bearing survives it.
| Industry duty | continuous radial load plus axial thrust that reverses on start-up |
|---|---|
| Typical media | water, process fluid, washdown, solvent |
| Housing temperature | −20 to +150 °C |
| Material and grade | 440C martensitic stainless steel |
| Hardness | 58–60 HRC |
| Temperature ceiling | 250 °C |
| Corrosion / chemical | fresh water, food and mild chemicals; pits in chlorides |
| Relative cost | ≈3× of a standard 52100 bearing |
Food pumps are washed on the outside as well as flushed on the inside: 60–80 °C caustic, a rinse, and often a chlorine sanitiser. The bearing housing sits in that spray, and the seal that keeps the product in does not keep the wash out. 440C is the pragmatic answer — hard enough to keep the load rating, stainless enough to survive the cycle — provided the wash chemistry has no free chlorine.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Wet-end floating position | Deep groove ball | 440C, C3, 2RS, H1 grease | Closest to the seal leakage path; stainless races survive the wash. |
| Drive-end locating | Angular contact ball | 440C pair on request, or 52100 with zinc-nickel | Thrust needs hardness; where load is high, coated 52100 is the cheaper compromise. |
| Sanitary lobe pump | Tapered roller | 440C on special order | Combined load at low speed; stainless avoids rust staining the product zone. |
| Material | Fit here | Choose it when |
|---|---|---|
| 440C | Best fit | CIP with caustic and rinse water, at 58–60 HRC and about 90% of the 52100 rating. |
| 316 | Workable alternative | Brine, hypochlorite or acid CIP: no pitting, but roughly half the capacity. |
| Si3N4 | Workable alternative | Where the pump may run dry or the product must stay metal-free — ask about full ceramic. |
The material will. The audit looks at lubricant, cleanliness and documentation, so the H1 grease and the 3.1 certificate matter as much as the grade.
No. Brine is a chloride environment and 440C pits. Use 316 or a hybrid with ceramic balls.
Ideally. A stainless cage removes the last rust source, and PTFE or PEEK cages also reduce wear against the balls.
Hardness, temperature, corrosion and equivalents for 440C stainless.
Read →Typical duty, recommended types and suffixes for pumps.
Read →Standard process pumps — impeller and seal-side positions in ISO and ANSI process pumps.
Read →Chemical & seawater — chemical process, seawater and brine pumps where 440C would pit.
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.