A metric SAE chart translates SAE J1939 and J1939-13 standards into familiar inch-pound values for hose, tube, and fittings. Mechanics and engineers rely on this reference when specifying hydraulic lines, fuel rails, and coolant circuits.
Use this reference to confirm pressure ratings, flow compatibility, and interchangeability across mobile equipment and industrial machines.
| Metric Size (mm) | Nominal Inch Size | Typical Inside Diameter (mm) | Max Working Pressure (bar) |
|---|---|---|---|
| 6 | 1/4 | 4.4 | 400 |
| 8 | 5/16 | 5.8 | 350 |
| 10 | 3/8 | 7.2 | 315 |
| 12 | 1/2 | 9.0 | 250 |
| 16 | 5/8 | 12.5 | 200 |
| 22 | 3/4 | 17.0 | 160 |
Understanding SAE Hose Size Standards
SAE size labels inform fitting selection, clamp choice, and leak testing procedures for every hydraulic circuit. Matching the chart entries to your equipment datasheet reduces field rework and warranty claims.
Standard Pressure Classes
Each nominal size supports multiple pressure classes, so you must verify the exact rating for the fluid and temperature range in your application.
Thread and Clamp Compatibility
BSP, JIC, and ORFS fittings require corresponding clamps and sleeves, and the metric SAE chart helps you order the correct hardware without trial and error.
Metric SAE Chart for Hose Assemblies
The metric SAE chart for hose assemblies aligns pinch clamps, cut lengths, and swivel fittings with standardized bore dimensions. Technicians use these values to cut hoses cleanly and install sleeves consistently.
Cutting Guidelines
Always square the hose end and remove a thin slice before measuring insertion depth to prevent ovality and pressure losses at the crimp.
Bend Radius Limits
Follow the minimum bend radius rules printed near the size block to avoid collapsing the wire braid and reducing fatigue life.
Metric SAE Chart for Tubing and Fittings
Metric SAE chart values for tubing include tube wall thickness and fitting shoulder dimensions that affect flare integrity and torque specs. These details matter when joining high-pressure fuel lines or return circuits.
Flare Angle Standards
37° flares for JIC fittings and 45° flares for automotive fuel systems both appear on the metric SAE chart to guide mandrel selection and nose angle setup.
Torque and Tightening Sequence
Adhere to the sequence shown in service manuals and the tightening ranges suggested in the metric SAE chart to distribute clamp force evenly.
Metric SAE Chart for Pressure and Flow
Pressure and flow ratings on the metric SAE chart help size lines for peak demand conditions, including transient spikes from steering valves or implement cylinders.
Velocity Recommendations
Keep flow velocity below specified limits to dampen pulsation, reduce erosion, and minimize noise in closed-loop systems.
Thermal Expansion Compensation
Account for length change under temperature swings by installing carefully calculated loops or using vibration-resistant clamps referenced in the metric SAE chart.
Optimizing Hydraulic Reliability with the Metric SAE Chart
Rigorous adherence to the metric SAE chart across design, procurement, and maintenance strengthens system reliability and reduces troubleshooting time.
- Confirm nominal and actual dimensions before cutting or ordering parts.
- Match pressure class, temperature range, and fluid compatibility for each line segment.
- Follow bend radius and clamp spacing rules to avoid collapsed hose or fatigue failure.
- Document revisions and retain charts alongside service records for future upgrades.
- Train technicians on reading both metric and nearest inch-pound equivalents to avoid mix-ups.
FAQ
Reader questions
How do I choose the correct clamp type for a given metric size?
Select worm gear clamps for frequent adjustments and stamped steel or spring clamps for permanent assemblies, always matching the band width to the row indicated in the metric SAE chart.
Can I use a hose rated below the system pressure if I reduce the flow?
No, pressure rating is independent of flow; use only hose meeting or exceeding the maximum working pressure listed for the size in the metric SAE chart.
What is the impact of using an undersized tube on hydraulic efficiency?
Undersized tube increases velocity, raises temperature, and causes higher pressure drop, which may degrade actuator response and pump performance.
How do I verify that a replacement fitting matches the metric SAE chart specifications?
Check markings on the fitting body, measure critical dimensions with calipers, and cross-reference the data against the chart before ordering or cutting.