Long straight grease nipples, also called extended grease nipples, are straight grease fittings with an extended body for recessed and deep-set lube points. IsoHiTech supplies M6x1.0 to M12x1.5 metric, 1/4-28 UNF, and NPT threads in 29 mm, 35 mm, and 40 mm lengths.
What a Long Straight Grease Nipple Is
A long straight grease nipple is an extended-body straight fitting in the conical-head form; the head follows the DIN 71412 form. A spring-loaded ball check acts as a one-way valve, sealing the passage at release. The longer body pushes the head past shrouds to deep-set points: bearing housings behind guards, drive shafts, linear guides, spindles. Button-head forms exist for the same threads but take their own couplers.
Specifications
| Item | Specification |
|---|---|
| Metric threads | M6x1.0, M8x1.0, M8x1.25, M10x1.0, M10x1.25, M10x1.5, M12x1.5 |
| Imperial threads | 1/4-28 UNF, 1/8 NPT, 1/4 NPT |
| Hex across flats | M6 = 7 mm, M8 = 9 mm, M10 = 11 mm, M12 = 14 mm |
| Standard overall lengths | 29 mm, 35 mm, 40 mm |
| Thread length | 5.5-10 mm depending on size |
| Custom assemblies | Press-fitted extension tubes to customer-specified length, up to 300 mm (special order) |
| Check valve | Spring-loaded ball check, one-way |
| Head | Conical head for a standard jaw-type coupler |
| Working pressure | 400 bar (5,800 PSI) |
| Materials | Zinc-plated carbon steel, stainless steel, brass |
How Length Is Measured and Which Length to Choose
Length is the overall length, thread included: the full body from the thread end to the tip of the head. The threaded part is 5.5-10 mm depending on size; the standoff past the mounting face is what remains. A 29 mm body suits a shallow recess behind a light guard; 35 or 40 mm suits counterbores and bearing-housing depth. Deeper means an extension tube. See M8 grease nipples and M12 grease nipple pages.
Long Body or Extension Pipe?
A long body wins when the port is recessed in the same casting and only needs standoff: one part, fewer joints, nothing extra to route. An extension assembly wins when the point sits deep or must be routed away; press-fitted tubes go to 300 mm as a special order. Every added joint is a leak path. For the full logic, read the guide to grease nipple extensions.
Couplers, Flow, and Leverage
Head and internal passage match a standard straight fitting, so a standard jaw-type coupler fits. The change is leverage: a side load from a misaligned gun puts bending load on the hex and thread. Seat the coupler straight, push along the axis, and never pry on the nipple. Full pairing lives in the grease zerk sizes and fitting chart.
Threads and Mix-Ups
Metric, UNF, and NPT threads are not interchangeable, nor are they with BSP. An M6x1.0 or M10x1.5 nipple will not seat in a 1/4-28 UNF or 1/8 NPT port; verify with a thread gauge. The classic mix-ups are M8x1.0 against 1/4-28 UNF and 1/8 NPT against BSP. The 1/4-28 UNF grease nipple page covers that size; metric threads and hex sizes are under metric grease fittings.
Materials and Installation
Zinc-plated carbon steel covers general-duty use; stainless suits exposed and washdown duty (see stainless steel grease nipples); brass fits non-ferrous or non-sparking needs. Clean the port, hand-start the nipple two to three turns, then snug the hex. Skip PTFE tape or sealant; debris washes into the passage under the ball check. Pump grease after fitting and confirm flow. For sizes outside the table, contact us for a quote.
Frequently Asked Questions
What is a long straight grease nipple?
A straight grease fitting with an extended body; the head follows the DIN 71412 form. A spring-loaded ball check seals at release; the extra body carries the head past guards to deep-set points.
How is the length measured?
Overall length, thread included: the full body from the thread end to the tip of the head. The threaded part is 5.5-10 mm; the standoff past the mounting face is what remains.
How do I choose between 29 mm, 35 mm, and 40 mm?
Match the body to the recess: 29 mm for a shallow recess behind a light guard; 35 or 40 mm for counterbores and housing depth. Deeper means an extension tube.
Can I get a body longer than 40 mm?
Yes. Catalog bodies stop at 40 mm; press-fitted extension tubes go to a customer-specified length up to 300 mm. See the guide to grease nipple extensions.
Should I use a long nipple or an extension pipe?
Long body when the port sits in one casting and only needs standoff; extension assembly when the point is deep or routed away, out to 300 mm.
Will my standard grease gun coupler fit?
Yes. The head keeps the standard conical form, so a standard jaw-type coupler fits; check jaw room and approach straight.
Does the extra length cut grease flow?
No. The internal passage matches a standard fitting, so body length does not restrict flow; back-pressure comes from the bore, grease condition, and elbows.
Can a long nipple bend or break?
Yes. The long body is a lever arm; side loads concentrate at the hex and can bend it. Approach straight on and seat fully.
Are metric, UNF, or NPT threads interchangeable?
No. They differ in pitch, form, and seat, and close diameters cross-thread easily; verify M8x1.0 against 1/4-28 UNF with a thread gauge.
Related Pages
- Grease nipple extensions
- M8 grease nipples
- M12 grease nipple
- 1/4-28 UNF grease nipple
- Metric grease fittings
- Stainless steel grease nipples
- Grease zerk sizes and fitting chart
For a custom body length or mixed-thread order, contact us for a quote.
