A pin type grease nipple – the fitting buyers often call a grease pin – is the pin-head member of the grease nipple family. Instead of the familiar conical head, it presents a pin or slotted head that only a matching pin-type coupler engages. That is the boundary, stated plainly: a standard hydraulic coupler does not fit a pin type nipple at all. These fittings survive mainly on marine equipment and legacy machines, which is why IMPA catalog codes appear on this page; the wider family is mapped in the grease fitting types guide.
Specifications
| Item | Specification |
|---|---|
| Material | Chrome-nickel plated steel, plating 5-8 microns |
| Head diameter | Approx. 9.9 mm |
| Working pressure | Up to 10,000 PSI |
| Temperature range | -20°C to +120°C |
| Threads | PF (parallel) and PT (tapered) pipe threads; 1/8″, 1/4″, 3/8″, 1/2″ |
| Packaging | 25, 50, and 100 piece packs |
PF or PT Thread
Two pipe-thread families cover the range. PF is the parallel form: it seals on a washer or a machined face and suits housings cut for parallel threads. PT is the tapered form: it seals on the thread flanks as it tightens, suiting cast housings and field repairs. Both families come in 1/8″, 1/4″, 3/8″, and 1/2″. Match whichever thread is already cut in the machine – the grease zerk sizes chart helps identify threads by measurement, and machines with metric threads belong to the metric grease fittings range instead.
IMPA Catalog Codes
Marine purchasing runs on IMPA codes, so the range is listed with them below. Treat these codes as catalog references for ordering, not as a certification or a tested rating.
| IMPA code | Description | Size |
|---|---|---|
| 617621 | Pin type, PF, plated steel | 1/8″ |
| 617622 | Pin type, PF, plated steel | 1/4″ |
| 617623 | Pin type, PF, plated steel | 3/8″ |
| 617624 | Pin type, PT, plated steel | 1/8″ |
| 617625 | Pin type, PT, plated steel | 1/4″ |
| 617626 | Pin type, PT, plated steel | 3/8″ |
| 617627 | Pin type, PT, plated steel | 1/2″ |
Pin Type vs Button Head vs Hydraulic
Three nipple styles cover most locking and high-pressure duty, and they are not interchangeable. The comparison is qualitative, with the familiar market pressure figures kept for orientation:
| Feature | Pin type | Button head | Hydraulic |
|---|---|---|---|
| Coupler required | Pin-type coupler only | Standard couplers | Hydraulic couplers |
| Locking | Positive pin lock | None | None |
| Pressure handling | Up to 10,000 PSI | Up to 6,000 PSI | Up to 8,000 PSI |
| Typical setting | Marine, legacy, high-vibration points | High-volume chassis work | General machinery |
Where They Are Found
Pin type fittings persist on legacy industrial machines, marine deck and engine-room equipment, and high-vibration points where a locking coupler justifies the dedicated tooling. If the machine is already fitted with them, keep the fleet consistent: mixing pin type with standard nipples on the same machine forces the crew to carry two couplers.
Maintenance Notes
Clear a blocked nipple with a wire through the head rather than forcing grease pressure up. Replace the fitting on thread damage or a bent or worn pin – a damaged pin lets the coupler slip under pressure. In dirty environments, fit protective caps between service intervals.
What This Page Does Not Claim
Three things, plainly. Standard grease gun couplers do not fit these fittings; you need the pin-type coupler. The IMPA codes are catalog references for marine purchasing, not a quality certification. And we make no blanket grease-compatibility guarantee for unusual high-viscosity or solid-filled lubricants – verify with us before ordering for those. For aggressive corrosion environments, see the stainless steel grease nipples range.
To order, give us the thread form and size, the quantity, and the coupler you run, or contact us for a quote.
Frequently Asked Questions
What is a pin type grease nipple?
A grease nipple that presents a pin or slotted head instead of a conical head. Only a matching pin-type coupler engages it, giving a positive lock under pressure and vibration.
Can I use a regular grease gun on it?
No. A standard hydraulic coupler does not fit the pin head; the gun needs a pin-type coupler.
What do people mean by “grease pin”?
Usually this fitting itself – the pin-head nipple. Occasionally the term refers to the mating pin inside the coupler. It is not a needle fitting for sealed bearings.
Pin type vs button head vs hydraulic – which is which?
Pin type locks onto a dedicated pin coupler, button head takes standard couplers at high volume, and hydraulic is the everyday conical-head nipple. The grease fitting types guide walks through the whole family.
What are the IMPA codes for?
They are catalog references used in marine purchasing and ship supply, so a buyer can order by code. They are not a certification and imply no tested rating.
How is this different from a hook-on nipple?
A hook-on grease nipple keeps the standard conical head, so an ordinary hydraulic coupler still works on it; a pin type nipple requires its pin-type coupler and accepts nothing else.
PF or PT thread – how do I choose?
Match the thread already in the machine. PF is parallel and seals on a washer or face; PT is tapered and seals on the thread flanks as it tightens. Both come in 1/8″ to 1/2″.
What pressure and temperature does it handle?
Working pressure up to 10,000 PSI and a temperature range of -20°C to +120°C, in chrome-nickel plated steel.
Where are pin type fittings actually found?
On legacy machines, marine equipment, and high-vibration points. On recessed or guarded points, grease nipple extensions bring the fitting out to where the coupler can engage it.
How do I install a pin-type nipple without damaging the threads?
Start by matching the form: PF threads are parallel and seal on a washer or machined face, PT threads are tapered and seal on the thread flanks as they tighten. Clean the boss threads thoroughly, start the fitting by hand until it runs freely, then tighten with a wrench only until it seals — with PT, that means snug plus a small further turn; forcing a tapered fitting deeper cracks cast housings. Use a thread sealant compatible with grease where the joint needs it, and keep sealant out of the grease channel. Replace, rather than re-tighten, a fitting that still weeps at the thread.
My pin-type coupler is stuck on the fitting — how do I release it?
The positive pin lock that keeps the coupler engaged under vibration also means it will not slide off casually. Release the coupler’s locking sleeve fully (slide it back against its spring before pulling), then work the coupler off along the fitting axis — a sideways pull only jams the pin harder. If it is truly seized, relieve hose pressure first, then use penetrating oil at the head and gentle rotation. Never hammer the coupler body: the pin and the fitting head both deform, and the next engagement will leak or slip.
Can I mix pin-type and hydraulic nipples on the same machine?
Yes — the fittings do not affect each other — but plan for it. A pin-type head only accepts a pin-type coupler and a hydraulic head only accepts a hydraulic coupler, so mixed machines need both couplers on site, or a dual-head gun. A practical split: keep pin-type fittings at the high-vibration and legacy points where their positive lock pays for itself, and standard hydraulic nipples everywhere else. Standardizing per machine or per circuit keeps service carts simpler and makes a missed point easier to spot.
Related Pages
- Grease fitting types guide
- Grease zerk sizes chart
- Hook-on quick-lock grease nipples
- Metric grease fittings
- Stainless steel grease nipples
- Grease nipple extensions
Pin type fittings come in 25, 50, and 100 piece packs – contact us for a quote with your thread form, size, and quantity.
