Overview
The 1/8 BSP grease nipple is a threaded lubrication fitting that screws into a 1/8 BSP port and gives a grease gun coupler a secure connection point. It suits small to medium lubrication points and comes in straight, 45°, and 90° bodies in zinc-plated carbon steel, brass CZ121, or stainless steel 316L.
Head form follows DIN 71412; related dimensional standards: SAE J534, ISO 4570, BS 1712. Declared working pressure is 10,000 PSI (689 bar), the outlet bore is 1.0 mm, and the hex is 7 mm.
Specifications
| Parameter | Specification |
|---|---|
| Thread | 1/8 BSP, major diameter 9.728 mm |
| Pitch | 0.907 mm (28 TPI) |
| Thread angle | 55° |
| Hex size | 7 mm |
| Overall length | 16.5 mm (straight) / 19.0 mm (45°) / 21.5 mm (90°) |
| Outlet bore | 1.0 mm |
| Minimum thread engagement | 4 full turns |
| Working pressure (declared spec) | 10,000 PSI (689 bar) |
| Burst pressure (declared spec) | 16,000 PSI (1,103 bar) |
| Temperature range | -40°C to +150°C |
| Materials | Zinc-plated carbon steel; brass CZ121; stainless steel 316L |
| Tightening torque | Carbon steel 15-20 Nm; brass 12-18 Nm; stainless steel 18-25 Nm |
| Sealing | PTFE tape 2-3 wraps or anaerobic sealant; O-ring optional |
| Flow | Max approx. 0.8 L/min at 500 PSI; approx. 2.5 ml per stroke with a standard gun |
| Recommended working pressure | 1,500-3,000 PSI |
BSP or NPT: Identify the Thread Before You Tighten
BSP and NPT threads look almost identical, and a 1/8 NPT fitting will thread into a 1/8 BSP port for a few turns – but it will not seal. The thread forms differ: BSP uses a 55° angle with rounded crests, while NPT uses a different angle with flattened crests. The pitch differs (28 TPI here), and NPT is tapered while BSP fittings come in parallel and tapered forms – confirm the form when ordering. Cross-fitting damages both threads and leaves a leak path.
To confirm you have BSP: measure the major diameter (9.728 mm), count the threads (28 TPI), and check whether the thread runs parallel or tapered. If your port is NPT, use an adapter – confirm at order.
| Port thread | Compatibility |
|---|---|
| BSP 1/8 | Direct fit |
| NPT 1/8 | Adapter required |
| Metric M8 | Not compatible |
Applications
- Industrial machinery: bearing housings, gearbox and motor lubrication points.
- Automotive and fleet: chassis points on vehicles built to BSP threading.
- Agriculture: tractor and implement pivot points.
- Marine and outdoor: brass or stainless versions where corrosion exposure is high.
- General maintenance: replacement fittings on imported equipment with BSP ports.
Installation
- Confirm the port is 1/8 BSP using the identification steps above; never force an NPT fitting into a BSP port.
- Apply PTFE tape (2-3 wraps) or anaerobic sealant to seal the thread joint. An O-ring is optional.
- Thread the nipple in by hand for at least 4 full turns to avoid cross-threading.
- Tighten with a 7 mm wrench to the torque for your material: 15-20 Nm carbon steel, 12-18 Nm brass, 18-25 Nm stainless steel.
- Choose the body angle for access – straight, 45°, or 90°.
Request a quote for material and angle combinations.
Maintenance
Inspect regularly: clear a blocked 1.0 mm outlet, and replace the nipple if the threads are stripped, the hex rounds off, or grease leaks past the threads after re-sealing. Replacement is condition-based, not calendar-based; inspection frequency depends on environment and grease cleanliness.
FAQ
What is a 1/8 BSP grease nipple?
A small threaded fitting screwed into a machine’s 1/8 BSP port. A grease gun coupler clips onto its head to deliver grease to the lubrication point; the head form follows DIN 71412.
What does BSP mean?
BSP stands for British Standard Pipe, a thread standard with a 55° thread angle, widely used on British and international equipment.
Can I use a 1/8 NPT fitting in a 1/8 BSP port?
No. It threads in for a few turns but will not seal: the thread angle and pitch differ (55° and 28 TPI on BSP), and NPT is tapered while BSP comes in parallel and tapered forms. Use an adapter – confirm at order.
How do I confirm my thread is 1/8 BSP?
Measure the major diameter (9.728 mm), count the threads (28 TPI, a 0.907 mm pitch), and check whether the thread is parallel or tapered. For a wider comparison, see our grease fitting types guide.
What pressure can a 1/8 BSP grease nipple handle?
The declared working pressure is 10,000 PSI (689 bar), but the actual system limit is set by your grease gun and hose. Recommended working pressure is 1,500-3,000 PSI.
What is the difference between working and burst pressure?
Working pressure is the declared continuous rating; burst pressure is where a part fails. The declared burst figure of 16,000 PSI (1,103 bar) is 1.6x the working rating, in line with common industry convention – it is not a license to operate above 10,000 PSI.
Which material should I choose?
Zinc-plated carbon steel for general industrial use; brass CZ121 or stainless steel for marine and outdoor exposure; 316L stainless for high temperature or chemical environments.
Straight, 45°, or 90° – which body do I need?
Straight (16.5 mm) where the gun couples head-on; 45° (19.0 mm) or 90° (21.5 mm) where clearance is restricted. For high-volume points see our DIN 3404 button head fittings; for metric threads see the M6 DIN 71412 nipple.
How do I install a 1/8 BSP grease nipple?
Apply PTFE tape (2-3 wraps) or anaerobic sealant, hand-start at least 4 full turns, then tighten with a 7 mm wrench to the torque for your material (15-20 Nm carbon steel, 12-18 Nm brass, 18-25 Nm stainless steel).
When should I replace a grease nipple?
By inspection, not by calendar: replace when the outlet stays blocked, threads are stripped, the hex rounds off, or grease leaks after re-sealing. To confirm thread, material, or angle, contact our team for a quote – IsoHiTech Lubrication Systems, founded in 2023, engineering since 2006; inquiry@isohitech.com.
