Permaswage® D9855 & D10255 Tee Fittings: Complete Technical Guide & Part Number Reference
Permaswage® D9855 and D10255 Tee Fittings are permanent tube fittings used throughout the Permaswage® 3,000 PSI Tube Connecting System. These fittings are designed to permanently connect three sections of tubing of the same size, allowing fluid flow to branch from a single line while maintaining the strength and reliability required for aerospace hydraulic systems.
The D9855 series covers tube sizes from 3/16 inch (-03) through 1 inch (-16). For larger tube sizes, the D10255 series continues the same fitting family for 1-1/4 inch (-20) and 1-1/2 inch (-24) tubing.
Because Tee fittings are commonly used wherever a hydraulic, pneumatic, lubrication, or fuel line must split into two separate directions, they are widely found throughout commercial aircraft, military aircraft, helicopters, and aerospace manufacturing.
In this guide, we'll explain what Permaswage® D9855 and D10255 Tee Fittings are, how they work, where they are commonly used, and provide a complete manufacturer part number reference.
What Is a Permaswage® D9855 Tee Fitting?
A Permaswage® D9855 Tee Fitting is a permanent three-port tube fitting that connects three tubes of the same outside diameter.
Unlike reducers or elbow fittings, all three ports of a Tee fitting accept the same tube size. Once installed using the approved Permaswage® swaging process, the fitting becomes a permanent part of the tube assembly.
The result is a compact, leak-resistant branch connection capable of withstanding the vibration, pressure cycling, and demanding operating environments found throughout modern aircraft.
Why Use Permaswage® Tee Fittings?
The D9855 and D10255 Tee fitting family offers numerous advantages for aerospace tube systems.
- Creates a permanent three-way tube connection
- Connects three tubes of the same size
- No tube flaring required
- Designed for 3,000 PSI applications
- Permanent leak-resistant installation
- Excellent vibration resistance
- Outstanding fatigue performance
- Compact fitting design
- Reduces potential leak paths
- Proven performance in commercial and military aircraft
Permaswage® D9855 & D10255 Tee Fitting Part Numbers
The following table lists the standard Permaswage® Tee fitting part numbers by tube size.
| Tube Size | Dash Size | Part Number | Series |
|---|---|---|---|
| 3/16" | -03 | D9855-03 | D9855 |
| 1/4" | -04 | D9855-04 | D9855 |
| 5/16" | -05 | D9855-05 | D9855 |
| 3/8" | -06 | D9855-06 | D9855 |
| 1/2" | -08 | D9855-08 | D9855 |
| 5/8" | -10 | D9855-10 | D9855 |
| 3/4" | -12 | D9855-12 | D9855 |
| 1" | -16 | D9855-16 | D9855 |
| 1-1/4" | -20 | D10255-20 | D10255 |
| 1-1/2" | -24 | D10255-24 | D10255 |
Available Tube Sizes
The Permaswage® D9855 and D10255 Tee fitting family is available in the following tube sizes:
- 3/16 inch (-03)
- 1/4 inch (-04)
- 5/16 inch (-05)
- 3/8 inch (-06)
- 1/2 inch (-08)
- 5/8 inch (-10)
- 3/4 inch (-12)
- 1 inch (-16)
- 1-1/4 inch (-20)
- 1-1/2 inch (-24)
This broad range allows the same fitting family to be used throughout an aircraft's hydraulic and fluid systems while maintaining a consistent permanent swaged installation method.
Permaswage® D9855 & D10255 Tee Fitting Dimensions
The following manufacturer dimensional reference table provides the overall fitting dimensions for the Permaswage® D9855 and D10255 Tee fitting family.
| Tube Size | Part Number | Dimension A | Dimension B |
|---|---|---|---|
| 3/16" (-03) | D9855-03 | 0.860 | 0.325 |
| 1/4" (-04) | D9855-04 | 1.050 | 0.390 |
| 5/16" (-05) | D9855-05 | 1.120 | 0.465 |
| 3/8" (-06) | D9855-06 | 1.190 | 0.550 |
| 1/2" (-08) | D9855-08 | 1.755 | 0.705 |
| 5/8" (-10) | D9855-10 | 1.860 | 0.866 |
| 3/4" (-12) | D9855-12 | 1.990 | 1.041 |
| 1" (-16) | D9855-16 | 2.344 | 1.385 |
| 1-1/4" (-20) | D10255-20 | 2.535 | 1.697 |
| 1-1/2" (-24) | D10255-24 | 2.778 | 1.885 |
Approximate Weight by Material
The following table lists the approximate fitting weights published by the manufacturer.
| Part Number | CRES (lbs.) | Aluminum (lbs.) | Titanium (lbs.) |
|---|---|---|---|
| D9855-03 | 0.019 | 0.006 | 0.011 |
| D9855-04 | 0.031 | 0.011 | 0.018 |
| D9855-05 | 0.047 | 0.016 | 0.027 |
| D9855-06 | 0.051 | 0.020 | 0.033 |
| D9855-08 | 0.159 | 0.054 | 0.090 |
| D9855-10 | 0.229 | 0.078 | 0.130 |
| D9855-12 | 0.302 | 0.103 | 0.172 |
| D9855-16 | 0.686 | 0.235 | 0.380 |
| D10255-20 | 0.979 | 0.308 | 0.554 |
| D10255-24 | 1.404 | 0.481 | 0.800 |
Common Aerospace Applications
Permaswage® Tee fittings are commonly used wherever a fluid system requires one line to branch into two while maintaining a permanent, leak-resistant connection.
- Aircraft hydraulic systems
- Fuel distribution systems
- Pneumatic systems
- Lubrication systems
- Environmental Control Systems (ECS)
- Landing gear hydraulic circuits
- Flight control systems
- Engine fluid systems
- Military aircraft maintenance
- Aerospace manufacturing and MRO operations
How the D9855 & D10255 Tee Fittings Work
After the tubing has been properly cut, deburred, and prepared, the Permaswage® Tee fitting is positioned onto the three tube ends. Using approved Permaswage® swaging equipment, each port is permanently swaged onto the tubing, creating a durable three-way connection.
This permanent installation eliminates threaded joints and flare connections, providing excellent resistance to vibration, pressure cycling, and fatigue while maintaining reliable system performance.
Frequently Asked Questions
What is a Permaswage® D9855 fitting?
The D9855 fitting is a permanent Tee fitting that connects three tubes of the same size.
What is the difference between D9855 and D10255?
D9855 covers tube sizes from -03 through -16, while D10255 is used for the larger -20 and -24 tube sizes.
Can Tee fittings be reused?
No. Permaswage® Tee fittings are permanent fittings and should not be reused after installation.
What pressure system are these fittings designed for?
The D9855 and D10255 fitting families are part of the Permaswage® 3,000 PSI Tube Connecting System.
Where are Tee fittings commonly used?
They are used wherever a hydraulic, fuel, pneumatic, or lubrication line must branch into two separate directions.
Why Buy Permaswage® Tee Fittings from Top Flight Tools?
At Top Flight Tools, we specialize in sourcing new, surplus, and hard-to-find Permaswage® fittings and aerospace tube tooling. Whether you need a single Tee fitting or assistance identifying the correct part number, our team can help.
Conclusion
Permaswage® D9855 and D10255 Tee Fittings provide a permanent solution for creating three-way branch connections in aerospace fluid systems. Their compact design, permanent swaged installation, and proven reliability make them one of the most widely used Tee fitting families within the Permaswage® 3,000 PSI Tube Connecting System.
⚠️ Disclaimer
Top Flight Tools (TFT) is an independent reseller and is not affiliated with, sponsored by, or endorsed by Permaswage® or Precision Castparts Corp. (PCC). All product names, trademarks, and registered trademarks are the property of their respective owners. Any reference to Permaswage® products, specifications, or part numbers is provided for informational purposes only. All Permaswage® trademarks and part numbers remain the property of their respective companies.
While every effort is made to ensure the accuracy of the information provided, it is the customer’s responsibility to verify all specifications, compatibility, and suitability of products for their intended application prior to use. TFT assumes no liability for errors, omissions, or the misuse or misapplication of this information, and disclaims any responsibility for damages resulting from reliance on it.