What types of threads are used in power hydraulics?

Power hydraulics is a field in which the precision and leak-tightness of connections play a crucial role. To ensure the proper functioning of hydraulic systems, various types of threads are used. The selection of the appropriate thread depends on many factors, such as operating pressure, fluid type, component materials, and applicable industry standards.

Basic types of threads

• Metric threads: Most commonly used in hydraulics due to their simplicity and wide availability. They are characterized by a pitch in millimeters.
• Inch threads (BSP): Popular in Anglo-Saxon countries, they have a pitch in inches. In hydraulics, BSPP (pipe) and BSPT (tapered) threads are commonly found.
• UNF (Unified National Fine) threads: An American standard for fine-pitch threads, used in many hydraulic systems.
• ORFS threads: Special threads designed for leak-free connections, often used in hydraulic fittings.

Most common thread types:

• Metric: M5, M6, M8, M10, M12, M16, M18, etc.
• Inch (BSP): 1/8", 1/4", 3/8", 1/2", 3/4", 1", etc.
• UNF: 1/16"-27, 5/32"-24, 3/16"-24, etc.

Fittings and their threads

• Metric fittings: Most commonly used in hydraulic systems where a high degree of flexibility in component selection is required.
• JIC fittings (UNF threads): Used in hydraulic systems where high resistance to vibration and high pressures is required.
• ORFS fittings: Provide leak-tight connections, often used in mobile hydraulic systems.

What to consider when choosing a thread?

When selecting the appropriate thread, several important aspects should be considered:

1. Working pressure – for high pressures, threads with greater strength and precision are used.

2. Fluid type – for aggressive media, use threads made of corrosion-resistant materials.

3. Component material—threads should be made of materials with appropriate hardness and strength.

4. Industry standards—it is necessary to comply with applicable standards to ensure component compatibility.

Inch Thread Table