Hydraulic fittings are vital components in a hydraulic system, used to connect lines, ensure sealing, and withstand high pressures. Different types of fittings are used for different standards and conditions. In this article, we will introduce the standard meanings, dimensions, pressure ratings, sealing methods, applications and their differences of hydraulic fittings such as JIC, NPT, BSP, SAE, metric fittings, JIS, ORFS, etc. We will also cover the related knowledge of hydraulic adapters and hydraulic ferrules.
JIC Joints (Joint Industry Council)
JIC Fitting Standard Meaning:
JIC (Joint Industry Council) is a standard set by the Society of Automotive Engineers (SAE) and is widely used in hydraulic systems.
JIC Fittings Dimensional charts and ranges:
| Inch size | Dash size | Thread Size | Male Thread O.D. (in) | Female thread O.D (in) | ||
| 1⁄8 | -2 | 5⁄16 – 24 | 5⁄16 | 0.31 | 9⁄32 | 0.27 |
| 3⁄16 | -3 | 3⁄8 – 24 | 3⁄8 | 0.38 | 11⁄32 | 0.34 |
| 1⁄4 | -4 | 7⁄16 – 20 | 7⁄16 | 0.44 | 13⁄32 | 0.39 |
| 5⁄16 | -5 | 1⁄2 – 20 | 1⁄2 | 0.5 | 15⁄32 | 0.45 |
| 3⁄8 | -6 | 9⁄16 – 18 | 9⁄16 | 0.56 | 17⁄32 | 0.51 |
| 1⁄2 | -8 | 3⁄4 – 16 | 3⁄4 | 0.75 | 11⁄16 | 0.69 |
| 5⁄8 | -10 | 7⁄8 – 14 | 7⁄8 | 0.88 | 13⁄16 | 0.81 |
| 3⁄4 | -12 | 1 1⁄16 – 12 | 11⁄16 | 1.06 | 1 | 0.98 |
| 7⁄8 | -14 | 1 3⁄16 – 12 | 1 3⁄16 | 1.19 | 1 1⁄8 | 1.1 |
| 1 | -16 | 1 5⁄16-12 | 1 5⁄16 | 1.31 | 1 1⁄4 | 1.23 |
| 1 1⁄4 | -20 | 1 5⁄8 – 12 | 1 5⁄8 | 1.63 | 1 9⁄16 | 1.54 |
| 1 1⁄2 | -24 | 1 7⁄8 – 12 | 1 7⁄8 | 1.88 | 1 13⁄16 | 1.79 |
| 2 | -32 | 2 1⁄2 – 12 | 2 1⁄2 | 2.5 | 2 7⁄16 | 2.42 |
JIC Fitting Pressure ratings:
Working pressure: up to 5000 psi (depending on material and size)
JIC Fitting Sealing method:
Metal-to-metal sealing (37° taper contact)
JIC Fitting Uses:
Construction machinery, agricultural equipment, aerospace
Suitable for high-pressure hydraulic systems
JIC Fitting Difference with other fittings:
Compared with the SAE 45° fittings, JIC 37° fittings have better sealing, and higher pressure capacity.
NPT Fitting (National Pipe Thread Tapered)
NPT Fitting Standard Meaning:
NPT (National Pipe Thread Tapered) is the U.S. standard tapered pipe thread, which is widely used in North American market.
NPT Fitting Dimensional charts and ranges:
| Inch size | Threads per Inch | Male Thread O.D. (in) | Female thread O.D (in) | ||
| 1⁄8 | 27 | 13⁄32 | 0.41 | 3⁄8 | 0.38 |
| 1⁄4 | 18 | 17⁄32 | 0.54 | 1⁄2 | 0.49 |
| 3⁄8 | 18 | 11⁄16 | 0.68 | 5⁄8 | 0.63 |
| 1⁄2 | 14 | 27⁄32 | 0.84 | 25⁄32 | 0.77 |
| 3⁄4 | 14 | 1 1⁄16 | 1.05 | 1 | 0.98 |
| 1 | 11 1⁄2 | 1 5⁄16 | 1.32 | 1 1⁄4 | 1.24 |
| 1 1⁄4 | 11 1⁄2 | 1 21⁄32 | 1.66 | 1 19⁄32 | 1.58 |
| 1 1⁄2 | 11 1⁄2 | 1 29⁄32 | 1.9 | 1 13⁄16 | 1.82 |
| 2 | 11 1⁄2 | 2 3⁄8 | 2.38 | 2 5⁄16 | 2.3 |
NPT Fitting Pressure Rating:
Working Pressure: 3000 psi (with sealant or biotape)
NPT Fitting Sealing Method:
Thread Seal (with sealant or PTFE tape)
NPT Fitting Uses:
Low Pressure Hydraulics, Pneumatics, Water Pipes
NPT Fitting Differences from Other Fittings:
Similar to BSPT (BSPT) but with a different thread angle (NPT 60° vs. BSPT 55°).
BSP Fitting (British Standard Pipe)
BSP Fittings Standard Meaning：
BSP (British Standard Pipe) is the standard for British pipe threads, which are divided into BSPP (parallel thread) and BSPT (tapered thread).
BSP Fittings Dimensional charts and ranges:
| Inch size | Dash size | Thread Size | Male Thread O.D. (in) | Female thread O.D (in) | ||
| 1⁄8 | -2 | 1⁄8 – 28 | 3⁄8 | 0.38 | 11⁄32 | 0.35 |
| 1⁄4 | -4 | 1⁄4 – 19 | 33⁄64 | 0.52 | 15⁄32 | 0.47 |
| 3⁄8 | -6 | 3⁄8 – 19 | 21⁄32 | 0.65 | 19⁄32 | 0.60 |
| 1⁄2 | -8 | 1⁄2 – 14 | 13⁄16 | 0.82 | 3⁄4 | 0.75 |
| 5⁄8 | -10 | 5⁄8 – 14 | 7⁄8 | 0.88 | 13⁄16 | 0.80 |
| 3⁄4 | -12 | 3⁄4 – 14 | 1 1⁄32 | 1.04 | 31⁄32 | 0.97 |
| 1 | -16 | 1 – 11 | 1 5⁄16 | 1.30 | 1 7⁄32 | 1.22 |
| 1 1⁄4 | -20 | 1 1⁄4 – 11 | 1 21⁄32 | 1.65 | 1 9⁄16 | 1.56 |
| 1 1⁄2 | -24 | 1 1⁄2 – 11 | 1 7⁄8 | 1.88 | 1 25⁄32 | 1.79 |
| 2 | -32 | 2 – 11 | 2 11⁄32 | 2.35 | 2 1⁄4 | 2.26 |
BSP Fittings Pressure ratings:
Working pressures: BSPP (3000 psi), BSPT (5000 psi)
BSP Fittings Sealing methods:
BSPP: O-ring or gasket seals
BSPT: Threaded seals (similar to NPT)
BSP Fittings Uses:
Hydraulic systems in Europe and Asia (e.g., excavators, injection molding machines)
BSP Fittings Differences from other fittings:
Incompatible with NPT (different thread angles).
SAE Fittings (Society of Automotive Engineers)
SAE Fitting Standard Meaning:
SAE fittings were developed by the Society of Automotive Engineers and are commonly SAE 45° flare fittings and SAE straight thread O-ring seal fittings.
SAE Fitting Size Charts and Ranges:
SAE J1926-1 and ISO 11296-1
| Inch size | Dash size | Thread Size | Male Thread O.D. (in) | Female thread O.D (in) | ||
| 1⁄8 | -2 | 5⁄16 – 24 | 5⁄16 | 0.31 | 9⁄32 | 0.27 |
| 3⁄16 | -3 | 3⁄8 – 24 | 3⁄8 | 0.38 | 11⁄32 | 0.34 |
| 1⁄4 | -4 | 7⁄16 – 20 | 7⁄16 | 0.44 | 13⁄32 | 0.39 |
| 5⁄16 | -5 | 1⁄2 – 20 | 1⁄2 | 0.50 | 15⁄32 | 0.45 |
| 3⁄8 | -6 | 9⁄16 – 18 | 9⁄16 | 0.56 | 17⁄32 | 0.51 |
| 1⁄2 | -8 | 3⁄4 – 16 | 3⁄4 | 0.75 | 11⁄16 | 0.69 |
| 5⁄8 | -10 | 7⁄8 – 14 | 7⁄8 | 0.88 | 13⁄16 | 0.81 |
| 3⁄4 | -12 | 1 1⁄16 – 12 | 1 1⁄16 | 1.06 | 1 | 0.98 |
| 7⁄8 | -14 | 1 3⁄16 – 12 | 1 3⁄16 | 1.19 | 1 1⁄8 | 1.10 |
| 1 | -16 | 1 5⁄16 – 12 | 1 5⁄16 | 1.31 | 1 1⁄4 | 1.23 |
| 1 1⁄4 | -20 | 1 5⁄8 – 12 | 1 5⁄8 | 1.63 | 1 9⁄16 | 1.54 |
| 1 1⁄2 | -24 | 1 7⁄8 – 12 | 1 7⁄8 | 1.88 | 1 13⁄16 | 1.79 |
| 2 | -32 | 2 1⁄2 – 12 | 2 1⁄2 | 2.50 | 2 7⁄16 | 2.42 |
SAE Fitting Pressure Ratings:
45° Flare: 3000 psi
O-Ring Seal: 6000 psi
SAE Fitting Seal Type:
45° Flare: metal-to-metal
O-Ring: elastomer seal
SAE Fitting Uses:
Automotive, Construction Machinery, High Pressure Hydraulics
Difference between SAE Fittings and Other Fittings:
SAE O-Ring Fittings are more resistant to high pressures than JIC. SAE fittings are more resistant to high pressure than JICs.
Metric Thread
Metric Fitting Standard Meaning
Metric fittings adopt ISO standard, and the thread size is expressed in millimeters.
Metric Fitting Size Chart and Range:
| DIN 2353 L Tube O.D.(mm) | DIN 2353 S Tube O.D. (mm) | Metric Thread Size | Male Thread O.D. (mm) | Female Thread I.D (mm) |
| 6 | M12 x 1.5 | 12 | 10.5 | |
| 8 | 6 | M14 x 1.5 | 14 | 12.5 |
| 10 | 8 | M16 x 1.5 | 16 | 14.5 |
| 12 | 10 | M18 x 1.5 | 18 | 16.5 |
| 12 | M20 x 1.5 | 20 | 18.5 | |
| 15 | 14 | M22 x 1.5 | 22 | 20.5 |
| 16 | M24 x 1.5 | 24 | 22.5 | |
| 18 | M26 x 1.5 | 26 | 24.5 | |
| 22 | 20 | M30 x 2.0 | 30 | 28 |
| 28 | 25 | M36 x 2.0 | 36 | 34 |
| 30 | M42 x 2.0 | 42 | 40 | |
| 35 | M45 x 2.0 | 45 | 43 | |
| 42 | 38 | M52 x 2.0 | 52 | 50 |
Metric Fitting Pressure Rating:
Working Pressure: 3000~6000 psi
Metric Fitting Sealing Method:
Tapered Thread Seal or O-Ring Seal
Metric Fitting Usage:
European and Japanese Hydraulic Equipment
Difference Between Metric Fittings and Other Fittings:
Not Compatible with Fractional Fittings (JIC, NPT).
JIS Fitting (Japanese Industrial Standard)
JIS Fitting Standard Meaning:
JIS is a Japanese Industrial Standard, similar to BSP but slightly different.
JIS Joint Size Chart and Range:
Japanese Industrial Standard JIS 300 Flare
| Inch size | Dash size | Thread Size | Male Thread O.D. (in) | Female thread O.D (in) | ||
| 1⁄8 | -2 | 1⁄8 – 28 | 3⁄8 | 0.38 | 11⁄32 | 0.35 |
| 1⁄4 | -4 | 1⁄4 – 19 | 33⁄64 | 0.52 | 15⁄32 | 0.47 |
| 3⁄8 | -6 | 3⁄8 – 19 | 21⁄32 | 0.65 | 19⁄32 | 0.60 |
| 1⁄2 | -8 | 1⁄2 – 14 | 13⁄16 | 0.82 | 3⁄4 | 0.75 |
| 5⁄8 | -10 | 5⁄8 – 14 | 7⁄8 | 0.88 | 13⁄16 | 0.80 |
| 3⁄4 | -12 | 3⁄4 – 14 | 1 1⁄32 | 1.04 | 31⁄32 | 0.97 |
| 1 | -16 | 1 – 11 | 1 5⁄16 | 1.30 | 1 7⁄32 | 1.22 |
| 1 1⁄4 | -20 | 1 1⁄4 – 11 | 1 21⁄32 | 1.65 | 1 9⁄16 | 1.56 |
| 1 1⁄2 | -24 | 1 1⁄2 – 11 | 1 7⁄8 | 1.88 | 1 25⁄32 | 1.79 |
| 2 | -32 | 2 – 11 | 2 11⁄32 | 2.35 | 2 1⁄4 | 2.26 |
JIS Joint Pressure Rating:
Working Pressure: 3000~5000 psi
JIS Joint Sealing Method:
Metal Taper Seal
JIS Joint Usage:
Japanese Construction Machinery (e.g., Komatsu, Hitachi)
Difference with other joints:
Close to BSP, but different sealing angle.
ORFS Fitting (ORing Face Seal)
ORFS Fitting Standard Meaning:
ORFS (ORing Face Seal) adopts flat O-ring seal, which has excellent leakage prevention performance.
ORFS Fitting Size Chart :
SAE J1453 Standard (-6 to -32)
Pressure Rating:
Working Pressure: 6000 psi
Sealing Method:
Flat O-Ring Seal
Uses:
High-pressure, high-vibration environments (e.g., mining machinery)
Differences from Other Fittings:
More leak-proof than JIC/NPT, but at a higher cost.
Hydraulic Adapters
Hydraulic Adapters Function:
Used to convert different standard fittings (e.g. JIC to NPT).
Common types:
Straight, 90°, 45° elbow, tee
Material:
Carbon steel, stainless steel, brass
Hydraulic Hose Ferrule
Function:
Used for ferrule fittings to provide tightness and sealing.
Material:
stainless steel, carbon steel
Applicable standards:
DIN 2353, ISO 8434
How to choose the right hydraulic fitting?
| Fitting Type | Sealing Method | Pressure Rating | Primary Application | Compatibility |
| JIC | 37° Metal Taper | 5000 psi | Construction Machinery | Incompatible with SAE 45° |
| NPT | Threaded Seal | 3000 psi | Low-Pressure Hydraulics | Requires Sealant |
| BSP | O-Ring/Threaded | 5000 psi | European Equipment | Incompatible with NPT |
| SAE | O-Ring O-Ring/45° | 6000 psi | Automotive/High Pressure | Similar to JIC |
| Metric | O-Ring/Tapered | 6000 psi | Eurasian Equipment | Metric Only Systems |
| JIS | 30° Tapered | 5000 psi | Japanese Machinery | Similar to BSP |
| ORFS | O-Ring Flat | 6000 psi | High Vibration Environments | Specialty Designs |
Intelligent Machining Equipment Machining Hydraulic Fittings HD Video
Conclusion:
Selection of the Proper Hydraulic Fittings Needs to be Considered Pressure, sealing method, standards compatibility, and other factors need to be considered when selecting the right hydraulic fitting. If you are still not sure what type of hydraulic fittings and connections you need, we can help. Contact one of our engineers and we will help you solve the problem. If you need OEM/ODM, please feel free to contact us.
