Grease Nipples
A grease nipple is the mating point where grease enters the bearing: a spring-loaded ball check that opens under coupler pressure, then seals — grease stays in, grit stays out. The same part goes by zerk fitting or grease fitting, and it is the smallest component in the lubrication system that every other component is built around.
IsoHiTech catalogs nipples by head standard: DIN 71412 conical heads (the default on European and Asian machinery), DIN 3404 button heads for high-flow centralized feed, DIN 3405 flush heads for tight and wipe-clean spaces, and JIS B 1575 hydraulic-type heads on Japanese equipment. Threads run metric M4 through M12, BSP, NPT and SAE 1/4-28 UNF; angles straight, 45°, 67.5° and 90°; materials carbon steel, stainless 316 and brass.
Buying one is identification work: head standard, thread, angle, material — in that order. The catalog also carries caps and protective covers, extension fittings for buried points, Hiwin linear-guideway specials, and pin-type heads for marine and heavy-industry practice.
Identify by Head Standard
| Head type | Standard | Where you meet it |
|---|---|---|
| Conical, ball check | DIN 71412 | Default on EU and Asian machinery |
| Button head, high flow | DIN 3404 | Centralized systems, high-volume points |
| Flush / recessed | DIN 3405 | Tight spaces, wipe-down hygiene areas |
| Hydraulic type | JIS B 1575 / SAE J534 | Japanese equipment; US 1/4-28 UNF practice |
Cataloged Sizes and Materials
| Catalog page | Covers |
|---|---|
| DIN 71412 conical nipples | M6–M14 hardened steel, self-sealing taper |
| Hydraulic-type DIN 71412 | M6–M12, straight / 45° / 90°, 400 bar |
| DIN 3404 button heads | 16 mm and 22 mm high-flow heads |
| Giant button head | M22, 22 mm head, 15,000 PSI class |
| DIN 3405 concave flush | Low-profile recessed heads |
| JIS B 1575 metric | M6–M12 hydraulic type, steel |
| M6 nipples | M6×0.75, straight and angled |
| M10 nipples | M10×1.0 / 1.25 / 1.5 — the common Asian size |
| M12 nipples | M12×1.5, straight and angled |
| 1/8 BSP nipples | European parallel-thread practice |
| BSP grease fittings | BSP-threaded fittings beyond the 1/8 size |
| 90° angled fittings | Redirect access on blocked points |
| 67.5° angled fittings | DIN 71412 angle for very tight clearances |
| Brass nipples | M6–M12 & BSP, 350 bar, nickel-plated C36000 |
| Stainless steel nipples | SS316 for washdown and corrosion duty |
| Hiwin linear-guideway nipples | Specials for rails and blocks |
| Pin-type nipples | Marine and heavy-industry practice |
| Caps & protective covers | Keep dirt off the ball check between cycles |
| Extension fittings | Rigid, flex-hose and angle adapters for buried points |
Thread converters and elbow adapters for mismatched points sit on the grease fitting adapters page; pre-sorted kits of the common sizes on the zerk fitting kit page.
Zerk Fitting Thread Size Quick Reference
Grease zerks come in a small set of standard threads, and mismatched threads are the single most common reason a new fitting will not seat. Before ordering, check the old fitting or the tapped hole:
- 1/8 NPT (tapered) — the default on most US-made machinery, trucks, and agricultural equipment. Taper seals by tightening; do not over-wrap with tape.
- 1/4-28 UNF (straight, SAE) — the standard on automotive and light-duty equipment, including most passenger-car ball joints and U-joints.
- M6/M10x1/M14x1.5 metric straight — common on European and Asian machinery; M10x1 is the typical metric heavy-equipment size.
- 1/4 NPT and 1/16 NPT — larger hydraulics and compact instruments respectively.
A corroded hole that will not take a new zerk usually needs a thread chaser or re-tap one size up — driving the fitting in harder cracks the housing. For fittings that repeatedly shear off, switch to a line fitting with a hose whip so the zerk no longer takes torque from the grease gun coupler.
Grease Nipple FAQ
Are DIN, JIS and SAE heads interchangeable?
No. The head geometry — cone angle, ball seat, diameter — differs between standards, and a coupler seals properly only on the head it was built for. A four-jaw coupler that grips a DIN 71412 cone will leak or slip on a JIS hydraulic head at pressure. Standardize the coupler to the dominant head standard on each machine, and use adapters only as a documented exception.
Carbon steel, stainless or brass — how do I choose?
Carbon steel for general plant duty — cheapest, fully adequate indoors. Stainless 316 where water or chemicals reach the point: washdown food lines, paper mills, marine and outdoor equipment. Brass where sparking or marring matters and pressures are moderate. The material does not change the head standard; order both decisions together.
How do I identify an unknown thread?
Measure the outside diameter with a caliper and the pitch with a thread gauge: M10×1 is the single most common size on Chinese-built machinery, 1/4-28 UNF on US equipment, 1/8 BSP on European. Metric and BSP diameters sit close — 10 mm versus 9.7 mm — so pitch is the tiebreaker. When the point is damaged or ambiguous, a photo through the contact page settles it in one reply.
When does a point need 45°, 67.5° or 90°?
When the coupler cannot approach the nipple straight. The coupler must seat axially — it grips and seals on the head axis — so a nipple hidden behind a guard or between hoses gets an angled head that turns the access into open air. 67.5° is the DIN answer to the tightest clearances; extensions move the point entirely out of the obstruction.
Grease will not go in — is the nipple worn out?
Usually yes, or the old grease behind it has hardened. A worn ball check lets new grease back out around the coupler; a blocked passage builds pressure that pops the coupler off. Both are cured by unscrewing the old nipple and fitting a new one — they are consumables, cheaper than the bearing they feed. For points that chronically over-pressurize, relief-type fittings vent excess instead of blowing seals; see the grease line fittings page.
