Push-to-connect grease line fittings join nylon or thermoplastic lubrication tubing to pumps, metering devices, and lube points without tools or ferrules. The tube pushes in, an internal O-ring seals it, and a stainless steel gripping ring locks it; pressing the release ring frees it again. This page covers the grease line configuration family: straight, fixed and swivel elbow, union, tee, bulkhead, and reducing adapter bodies, with 1/8″ NPT, 1/4″-28 SAE, or M6x1 to M10x1 threads, for 1/4″ (6 mm) tube as standard and 1/8″ or 5/16″ as options, rated up to 80 bar (1,160 psi).
Which Fitting Page Do You Need
This family is built around inch-based systems: NPT and SAE threads with metric port options on several bodies, 1/8″ – 5/16″ tube, and every routing configuration from straight to bulkhead.
- For metric single fittings with BSP, UNF, or metric threads and 3 – 12 mm tube, use the push-up lubrication fitting page.
- For push-in vs compression selection, read the compression vs push-in fitting guide.
- For the tubing itself, see helical coil nylon pipe.
Specifications
| Body material | Nickel-plated brass (stainless steel optional) |
|---|---|
| Working pressure | Up to 80 bar (1,160 psi) |
| Temperature range | -20°C to +70°C |
| Tube sizes | 1/4″ (6 mm) standard; 1/8″ and 5/16″ optional |
| Thread options | 1/8″ NPT, 1/4″-28 SAE, M6x1, M8x1, M10x1 |
| Compatible tubing | Nylon (PA6, PA12) and thermoplastic tube |
| Grease compatibility | NLGI 000 – 2, petroleum-based and synthetic |
| Sealing mechanism | Push-in connection with internal O-ring and stainless steel gripping ring |
| Configurations | Straight, 90° fixed elbow, 90° swivel elbow, tube-to-tube union, tee, bulkhead, reducing adapter |
Choosing a Configuration
- Straight: direct tube-to-port connection, for example 1/4″ tube x 1/8″ MNPT or M6x1.
- 90° fixed elbow: where the tube approaches the port from the side.
- 90° swivel elbow: same routing; the body orients after the thread is tightened.
- Tube-to-tube union: extends a line or joins two cut sections.
- Tee: splits one supply line into two branches.
- Bulkhead: passes the tube through a panel or guard.
- Reducing adapter: steps between tube sizes, such as 5/16″ main to 1/4″ branch.
Thread and Tube Size Selection
Match the thread to the port: 1/8″ NPT is tapered, 1/4″-28 SAE is straight, and M6x1 / M8x1 / M10x1 are metric straight threads; they are not interchangeable.
Choose tube size by flow and line length, not by thread: 1/4″ (6 mm) covers most points, 1/8″ suits short low-flow branches, and 5/16″ suits higher flow or longer runs.
Tube-End Preparation
Sealing starts at the tube end. Four steps, every time:
- Cut square with a sharp tube cutter, within 2 degrees of perpendicular.
- Deburr the cut edge.
- Reject deformed or oval ends; cut back to a round section.
- Push in until the tube bottoms against the stop, then pull gently to confirm the grip.
Angled cuts, burrs, and oval ends are the leading causes of leaks.
Typical Applications
Machine tools, linear guides, spindle bearing circuits, conveyor lines, bearing housings, textile machinery, printing and packaging equipment, and factory automation running NLGI 000 – 2 grease lines.
Honest Limits
- 80 bar (1,160 psi) is the ceiling. Most centralized lubrication systems run at 20 – 60 bar (290 – 870 psi), inside the rating; above 80 bar these fittings are not the right choice.
- Tube-end preparation is a sealing prerequisite: skipped square cuts, burrs, or an omitted pull check are the leading cause of leaks.
- The rated envelope is -20°C to +70°C; anything outside must be confirmed before ordering. At points with severe pressure shocks or continuous vibration, compression fittings are the steadier option.
If your drawing mixes thread standards or tube sizes, send us your port and tube list and we will map each connection.
Frequently Asked Questions
Should I order from this page or the metric push-up fitting page?
Use this page for inch threads (1/8″ NPT or 1/4″-28 SAE), 1/8″ – 5/16″ tube, or elbow, tee, bulkhead, and reducer bodies. For metric M and BSP threads with 3 – 12 mm tube, go to the push-up lubrication fitting page.
Which tube size should I choose?
1/4″ (6 mm) is standard and covers most points. 1/8″ suits short low-flow branches; 5/16″ suits higher flow or longer runs. Choose by flow, line length, and pressure drop, not by thread.
How do I prepare the tube end?
Cut square with a sharp tube cutter, within 2 degrees of perpendicular, and deburr. Never install deformed or oval ends; cut back to a round section.
How do I confirm the tube is fully seated?
Push until the tube bottoms against the stop, then pull gently by hand. If it moves, release it, re-cut the end, and connect again.
Can these fittings be disconnected and reused?
Yes. Press the release ring and the tube comes out without tools. If the tube end shows grip marks, cut that section off and re-square it.
What tubing works with these fittings?
Nylon PA6 and PA12 tube and thermoplastic lubrication tube. Other plastics are not interchangeable and must be confirmed before ordering.
What grease can the lines carry?
NLGI 000 – 2 greases, petroleum-based and synthetic, within the -20°C to +70°C envelope.
When should I use compression fittings instead?
At points with severe pressure shocks, continuous vibration, or constant line flexing, a compression fitting holds more steadily. If unsure, ask our engineers.
Which configuration fits my routing?
Straight for a direct port; fixed or swivel elbows where the tube comes from the side; a tee to split a line; a bulkhead to cross a panel; a reducing adapter to change tube size.
Who makes these fittings?
IsoHiTech Lubrication Systems is a lubrication equipment supplier founded in 2023, engineering since 2006. For part numbers and availability, write to inquiry@isohitech.com.
