Over the last 2 months I have mainly been stripping and testing cylinders, which has been a great way to introduce myself to hydraulic systems and get to grips with a few core concepts.
Part of the testing is to hook the cylinder up to the test rig in the workshop or a powerpack and follow the process to check for leaks or signs of issues.
I have to say, the part of this I was not expecting to give me such a learning cure so quicky was simply finding the correct fitting at the correct size! Its crazy.
To try and help, below is the basic information on each type of fitting I have come across so far and a handy image or drawing of the characteristics of the fitting to look out for when identifying them.
Types of Hydraulic Hose Fittings
🛠️ 1. JIC (Joint Industry Council)
- Thread Type: UNF (Unified National Fine)
- Seal: 37° flare – metal-to-metal
- Region: North America
- Applications: High-pressure systems, aerospace, automotive, fluid power
- Notes: JIC fittings are very popular due to their reusability and strong mechanical seal.
- Notes: JIC fittings are very popular due to their reusability and strong mechanical seal.
🌍 2. BSP (British Standard Pipe)
- Types:
- BSPP – Parallel threads, sealed with O-rings or bonded washers
- BSPT – Tapered threads, sealed by thread interference
- Thread Angle: 55°
- Region: UK, Europe, Asia
- Applications: General-purpose hydraulics and machinery
- Notes: Very common in international systems and European machinery.
🇺🇸 3. NPT (National Pipe Tapered)
- Thread Type: Tapered
- Seal: Thread deformation with sealant (e.g., PTFE tape)
- Region: North America
- Applications: Plumbing and low-to-medium pressure hydraulics
- Notes: Easy to recognize due to tapered thread, but not recommended for high-vibration environments without additional sealing.
🖼️ Insert image of NPT fitting here
🟡 4. ORFS (O-Ring Face Seal)
- Thread Type: Straight (typically UNF)
- Seal: O-ring embedded in the flat face of the fitting
- Region: Global
- Applications: High-pressure, leak-free hydraulic systems (e.g., construction, agriculture)
- Notes: Ideal for high-pressure systems where leaks must be prevented.
🖼️ Insert image of ORFS fitting here
📏 5. Metric (DIN Standard)
- Thread Type: Metric (parallel or tapered)
- Seal: Metal-to-metal (flare), bite-type, or O-ring (depending on sub-type)
- Region: Europe and globally
- Applications: Mobile hydraulics, industrial systems
- Common Standards: DIN 2353, ISO 8434-1
- Notes: Common in European-built equipment. Metric threads can be confused with BSP, so double-check pitch and diameter.
🖼️ Insert image of metric DIN fittings here
🚗 6. SAE (Society of Automotive Engineers)
- Types:
- SAE J514 (O-Ring Boss or ORB) – Straight thread with an O-ring seal
- SAE Flange – Seals with a flange and bolts
- Region: USA and globally
- Applications: Automotive, heavy-duty hydraulic systems
- Notes: Offers excellent performance in high-pressure, vibration-prone environments.
🖼️ Insert image of SAE fitting (ORB and Flange) here
🇩🇪 7. DIN (Deutsches Institut für Normung)
- Thread Type: Metric
- Seal: Bite-type ring or O-ring
- Region: Germany, Europe
- Applications: Industrial hydraulics
- Notes: These fittings often use compression sleeves and are used widely in precision hydraulic systems.
🖼️ Insert image of DIN bite-type fitting here
🧱 8. Imperial / Whitworth
- Thread Type: Whitworth (BSW), UNF, or legacy NPT
- Seal: Varies
- Region: Older UK and US systems
- Applications: Legacy equipment, classic machinery
- Notes: Often found on vintage or imported equipment; rarely used in new builds.
🖼️ Insert image of Imperial fitting here
📊 Quick Comparison Table
| Fitting Type | Thread Style | Seal Type | Common Region | Notes |
|---|---|---|---|---|
| JIC | UNF 37° flare | Metal-to-metal | North America | Reusable, high pressure |
| BSPP | Parallel (55°) | O-ring or washer | UK, Europe, Asia | Common in Europe |
| BSPT | Tapered (55°) | Thread seal | UK, Europe, Asia | Used in plumbing & hydraulics |
| NPT | Tapered (60°) | Thread deformation | North America | Requires sealant |
| ORFS | Straight | Face O-ring | Global | Leak-proof, vibration proof |
| Metric DIN | Metric (60°) | Bite/O-ring/flare | Europe | Widely used in EU machinery |
| SAE (ORB) | UNF (straight) | O-ring boss | U.S., Global | Strong against vibration |
| DIN Bite | Metric | Compression/Bite ring | Germany, Europe | Precision industrial systems |
| Imperial | Whitworth, UNF, NPT | Varies | UK/US (legacy) | Old equipment only |
📌 Final Thoughts
Choosing the right hydraulic hose fitting is crucial for ensuring your system operates safely and efficiently. Always double-check thread size, pitch, and sealing method before installation, especially when working with equipment from different regions.
🧰 Tip: If you’re unsure, use a thread gauge or reference a fitting identification chart. Better yet, bring the sample fitting to your local hydraulic supplier.
Need help identifying a fitting? Upload a photo or reach out, and we’ll assist you.