316 is chosen for what it will not do: it will not rust, pit or contaminate. Everything else about it is a compromise. 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 | 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 |
The molybdenum in 316 is what resists chloride pitting, and that is the whole reason it appears in pumps. The cost is hardness: with no martensitic transformation available, the raceway stays soft, the balls brinell under load, and the load rating falls to about half. It also galls against itself, so a 316 ball on a 316 race needs a ceramic ball or a polymer cage to survive.
| Position | Bearing type | Material / finish | Why it works there |
|---|---|---|---|
| Chemical process pump, wet end | Deep groove ball | 316 rings and balls, PTFE or PEEK cage | No rust path into the product; the soft races limit load, not corrosion. |
| Seawater lift pump | Deep groove ball | 316 rings with Si3N4 balls | Ceramic balls restore capacity and stop fretting corrosion between ball and race. |
| Brine circulation | Ball bearing unit | 316 insert, 2RS, H1 grease | Housing and bearing both stainless, so no galvanic pair in the wet zone. |
| Material | Fit here | Choose it when |
|---|---|---|
| 316 | Best fit | Chlorides, acids and seawater, where pitting would end a 440C bearing in months. |
| ZrO2 | Workable alternative | Acid with abrasives: harder and inert, but it ages in hot water above 200 °C. |
| 440C | Workable alternative | Clean fresh water and food duty where load matters — twice the strength and a third of the price. |
Because it cannot be through-hardened. Hardness sets the contact fatigue limit, so a 25–30 HRC raceway carries roughly half the load of a 60 HRC one before it brinells.
Yes, and it is the usual choice for a lift pump. For continuous immersion with high flow, a hybrid with ceramic balls lasts longer because it removes the fretting between ball and race.
No. In a wet housing that is a galvanic couple and the steel ball rusts first, which then contaminates the whole bearing.
Hardness, temperature, corrosion and equivalents for 316 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 →Washdown & food pumps — food, beverage and CIP-washdown pumps where water reaches the bearing housing.
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.