Overview
DIN 3404 button head grease nipples are flat-head lubrication fittings built for high-volume grease delivery. The wide button head opens a much larger passage than a small conical head, so bearings with big grease chambers fill quickly at each service interval.
The head is a flat cylinder 10, 16, or 22 mm in diameter, and it engages a flat-jaw button-head coupler on the grease gun. The thread is cylindrical (parallel), not tapered, so these nipples do not self-seal: every installation needs PTFE tape or anaerobic thread sealant.
IsoHiTech Lubrication Systems supplies these fittings in zinc-plated carbon steel, stainless steel 1.4305 or 1.4404, and brass CuZn39Pb3, with metric, BSP, and NPT thread options.
Specifications
All values below are declared specifications.
| Parameter | Specification |
|---|---|
| Head diameter | 10 mm (Type M4), 16 mm (Type M1), 22 mm (Type M22); Type T1 hexagonal head with round collar, SW 15 |
| Overall length | 12-25 mm, by head size and thread |
| Thread length | 6-11.5 mm |
| Thread tolerance class | 6g / 6H |
| Working pressure | 400-600 bar (5,800-8,700 PSI); brass versions max 400 bar |
| Flow rate | 30-80 ml/min at 50 bar with NLGI 2 grease |
| Coupler clearance | 30-50 mm of free space around the head, by head size |
| Material | Operating temperature | Notes |
|---|---|---|
| Carbon steel, zinc-plated | -40°C to +120°C | Standard industrial use |
| Stainless steel 1.4305 | -40°C to +150°C | General corrosion resistance |
| Stainless steel 1.4404 | -40°C to +150°C | Marine, chemical, and washdown environments |
| Brass CuZn39Pb3 | -20°C to +120°C | Low-load points; max 400 bar |
| Thread family | Sizes |
|---|---|
| Metric | M6x1, M8x1, M10x1, M12x1.5, M16x1.5 (wrench flats SW 11 / 17 / 22 by size) |
| BSP parallel | G1/8, G1/4, G3/8 |
| NPT tapered | 1/8-27, 1/4-18, 3/8-18 (upon request – confirm at order) |
Applications
- Construction machinery: excavator pins, loader articulation joints, and crane slew bearings.
- Mining and quarrying: big plain bearings and pivot points on crushers, screens, and haul equipment.
- Steel and heavy industry: roll bearings and continuous-caster lubrication points fed in volume.
- Agriculture: combine and tractor joints serviced with a button-head coupler.
These nipples suit high-pressure delivery from a grease pump or heavy-duty gun equipped with the correct button-head coupler.
Installation
Clean the threads, then apply PTFE tape or anaerobic sealant to the male thread – cylindrical threads do not self-seal, and skipping sealant is the most common cause of weeping fittings. Tighten to the torque values below, and leave 30-50 mm of clearance around the head so the coupler clamps on squarely.
| Thread | Steel torque | Stainless torque | Min. thread engagement |
|---|---|---|---|
| M6x1 | 8-10 Nm | 6-8 Nm | 6 mm |
| M8x1 | 12-16 Nm | 10-13 Nm | 8 mm |
| M10x1 | 18-22 Nm | 15-18 Nm | 8 mm |
| M12x1.5 | 25-30 Nm | 20-25 Nm | 10 mm |
| M16x1.5 | 35-45 Nm | 28-35 Nm | 12 mm |
Before the first grease-up, confirm the gun carries a flat-jaw button-head coupler: a standard conical-jaw hydraulic coupler will not seal on this head. Request a quote with your thread size and head diameter.
Selection: DIN 3404 vs DIN 71412
Button head and conical head nipples solve different problems. DIN 3404 moves a large grease volume into heavy machinery points; DIN 71412 conical nipples are the general-purpose standard for smaller bearings – see our M6 DIN 71412 grease nipple page for that family and the grease fitting types guide for the wider range.
| Feature | DIN 3404 (button head) | DIN 71412 (conical head) |
|---|---|---|
| Head shape | Flat button head, 10 / 16 / 22 mm | Small conical head |
| Thread form | Cylindrical (parallel), sealant required | Tapered, self-sealing |
| Flow rate | High, 30-80 ml/min at 50 bar (NLGI 2) | Standard flow for general bearings |
| Coupler type | Flat-jaw button-head coupler | Hydraulic-type conical coupler |
| Typical use | Construction, mining, heavy machinery | General industrial and automotive bearings |
Maintenance
Inspect each nipple at every lubrication service. Replace it if the head is deformed, the threads are stripped, or the fitting leaks even with a sound coupler and fresh sealant. Replacement is condition-based, not calendar-based, so inspect regularly rather than swapping parts on a fixed schedule. Screw-on protective caps keep dirt off exposed heads between services.
FAQ
What is a DIN 3404 button head grease nipple?
It is the DIN-standard flat-head grease fitting for high-flow lubrication. The wide cylindrical head (10, 16, or 22 mm) accepts a button-head coupler and passes far more grease per stroke than a small conical nipple.
What is the difference between DIN 3404 and DIN 71412 nipples?
Four things: head shape (flat button vs small cone), thread form (parallel vs tapered self-sealing), flow capacity (high vs standard), and coupler (flat-jaw button-head vs conical hydraulic coupler). DIN 3404 serves large grease chambers; DIN 71412 covers everyday bearings.
Do DIN 3404 nipples need thread sealant?
Yes. The cylindrical thread does not self-seal, so apply PTFE tape or anaerobic thread sealant at every installation. Without sealant the joint will weep grease under pressure.
Will a standard grease gun coupler fit a DIN 3404 button head?
No. The common conical-jaw hydraulic coupler made for DIN 71412 heads cannot grip or seal on a flat button head. You need a flat-jaw button-head coupler matched to the head diameter.
Which material should I choose?
Zinc-plated carbon steel for standard indoor industrial use; stainless 1.4305 for general corrosion resistance; stainless 1.4404 for marine, chemical, or washdown areas; brass CuZn39Pb3 only for low-load points, since brass tops out at 400 bar.
Which thread sizes are available?
Metric M6x1, M8x1, M10x1, M12x1.5, and M16x1.5; BSP parallel G1/8, G1/4, and G3/8; NPT tapered 1/8-27, 1/4-18, and 3/8-18 upon request. State head diameter and thread together when ordering.
What is the maximum working pressure?
The declared working range is 400-600 bar (5,800-8,700 PSI) for steel and stainless versions, with brass limited to 400 bar. The practical ceiling is set by the weakest part of the chain – gun, hose, and coupler included.
How do I pick the head diameter?
Pick 10 mm (Type M4) for tight spaces and small bearings, 16 mm (Type M1) as the standard industrial choice, and 22 mm (Type M22) for construction machinery and large bearings where maximum flow per stroke matters.
Can I use DIN 3404 nipples on food processing equipment?
They can be specified for such plants, but choose stainless 1.4404 and make sure the lubricant itself meets the application’s food-industry requirements – that compliance sits with the grease, not the fitting. Confirm the full specification at order.
When should a grease nipple be replaced?
On inspection, not on a calendar. Swap the nipple when the head is deformed, the thread is damaged, the internal valve sticks, or it leaks despite correct sealant and a good coupler. For spares or a matched set, contact our team for a quote from IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006; email inquiry@isohitech.com.
