3/8 hydraulic fitting

3/8 hydraulic hose fittings meaning and core features

3/8 hydraulic hose fittings refer to standardized connections with an inside diameter of 3/8 inch (9.525mm), in accordance with international standards such as SAE J517 (steel wire braided hose standard) and ISO 8434 (ferrule fittings specification). Its core features include:
1. Wide pressure coverage: working pressure of 1570MPa, suitable for medium and high pressure hydraulic systems (e.g. forklift lifting device). 2;
2. sealing reliability: support for taper sealing (JIC 37 °), thread sealing (NPT) or O-ring sealing. 3. flexible adaptation: compatible with the U.S. and other international standards;
3. flexible adaptation: compatible with the American standard (SAE), European standard (DIN) and Japanese standard (JIS) hydraulic system.

3/8 Main types of hydraulic hose fittings

1. Classified according to the connection method

Main Thread Type Dimensions

Thread Fit Depth Requirements

JIC 37°: Minimum fit depth 8.5mm
NPT: Minimum screwing depth 10.2mm
BSPP: Minimum screwing depth 7.8mm

2. Classified by material

Carbon steel galvanized: economical and durable, suitable for conventional industrial environments (e.g. injection molding machines);
Stainless steel (304/316L): high corrosion resistance, suitable for wet environments such as chemical industry and ships;
Brass: low conductivity, used in flammable and explosive scenarios (e.g. oil and gas field equipment).

3. Categorized by structure

Straight-through type: 3/8 interface at both ends to extend the length of pipeline;
45°/90° elbow: optimize piping layout and reduce pressure loss;
Tee type: shunt hydraulic oil, suitable for multi-actuator system.

Price list of 3/8 hydraulic hose fittings in different sizes

How to identify 3/8 hydraulic hose fittings

1. Dimensional verification
Caliper measurement: thread O.D. ≈ 16.66mm (3/8” NPT) or hose I.D. ≈ 9.525mm;
Thread parameters:
NPT: 60° tapered thread, 18 TPI (teeth per inch);
BSPP: 55° parallel thread, 19 TPI.

2. Marking and certification
Standard marking: “3/8 JIC”, “SAE J517” or “ISO 8434” is engraved on the surface of the fitting;
Material code: e.g. “SS304” means 304 stainless steel, “ZN” means galvanized carbon steel.

3. Tool Inspection
Thread Gauge Inspection: Use NPT or BSPP special gauge to verify the thread matching;
Pressure test: pressurized to 1.5 times the working pressure (e.g. 45MPa) by hydraulic test bench, holding pressure for 5 minutes without leakage.

3/8 Hydraulic hose fittings installation specification

1. Preparation before installation

Cleaning treatment: Wipe the interface with isopropyl alcohol to remove oil and metal debris;
Seal selection:
JIC fittings: direct taper compression, no sealant required;
NPT joints: Wrap 23 layers of PTFE raw tape (clockwise) or apply liquid sealant.

2. Installation steps (JIC 37° as an example)

1. Pre-alignment: Insert the hose vertically into the fitting core, avoiding twisting;
2. manual preload: tighten the nut clockwise until resistance increases significantly;
3. Torque lock: apply standard force using a torque wrench (approximately 2530 N-m for a 3/8” JIC);
4. system pressure test: start the hydraulic pump gradually pressurized to the working pressure, observed for 10 minutes without leakage.

3.Installation Key Dimensions

Ferrules
Ferrules preload: 0.3-0.5mm
Ferrules edge angle: 24°±1°

Flare Type Fitting
Flare angle: 74°±2
Flare length: 6.5±0.3mm

Flange type Fitting
Bolt hole center distance：28.5mm
Bolt specification: M8×1.25

4.Torque Specification Reference

5. Critical Considerations

Avoid over-tightening: over-torquing can cause deformation of the taper (stainless steel is particularly sensitive);
Anti-cross-threading: manually pre-tighten before using the tool to ensure that the threads are aligned;
Environmental suitability: high humidity environments give preference to stainless steel and apply anti-corrosion grease.

Conclusion:

3/8 hydraulic hose fittings are ideal for medium-sized hydraulic systems because of their balanced flow and pressure resistance. Proper selection (e.g., 316L stainless steel for corrosive environments) and installation (following SAE torque standards) can significantly improve system reliability. For high frequency pulsation or extreme temperature scenarios, we recommend contacting our engineers for a customized solution.

3/8 hydraulic hose fittings Frequently Asked Questions

How do I measure the actual size of a 3/8 fitting?
Use digital calipers to measure:
1. Thread Diameter: Measure the diameter of the top of the thread.
2. Pitch: Measure the length of 10 threads and calculate.
3. Taper: Measure with a taper gauge.

Can I mix different standard 3/8 fittings?
JIC and BSPP are similar in size, but: JIC and BSPP are similar in size.
JIC and BSPP have similar dimensions but: different sealing methods
Differences in pressure ratings
may result in system failure.

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