II. Types of Hydraulic Fittings
Hydraulic fittings come in a variety of designs, each serving specific functions based on the system requirements, pressure ratings, and application environments. Understanding the different types of fittings is essential for selecting the right component to ensure efficiency and reliability in hydraulic systems.

1. Threaded Fittings
Threaded fittings are among the most common types, utilizing threads to create a secure and leak-proof connection. They are available in various threading standards:
- NPT (National Pipe Tapered): A widely used thread type in North America known for its taper, which tightens as the fitting is screwed in.
- BSP (British Standard Pipe): Common in Europe and Asia, available in tapered (BSPT) or parallel (BSPP) forms.
- Metric Threads: Used globally, offering compatibility with international systems.
Applications: Industrial machinery, automotive hydraulics, and general-purpose systems.
2. Flare Fittings
Flare fittings create a seal by flaring the end of a hose or tube at a specific angle, allowing it to fit snugly against the fitting body.
- 37-degree Flare (JIC): Standard for high-pressure applications.
- 45-degree Flare: Common in refrigeration and fuel systems.
Applications: Aerospace, automotive braking systems, and fluid transfer systems.
3. O-Ring Face Seal (ORFS) Fittings
ORFS fittings feature a flat face with an embedded O-ring, ensuring a tight, leak-proof seal even at high pressures.
- Key Feature: Excellent for vibration resistance and high-pressure environments.
Applications: Heavy machinery, construction equipment, and high-pressure industrial systems.
4. Compression Fittings
Compression fittings create a seal by compressing a ring (ferrule) around the pipe or tube as the fitting is tightened.
- Advantages: Provides strong seals without welding or flaring.
- Types: Single ferrule and double ferrule designs.
Applications: Instrumentation, hydraulic control systems, and gas lines.
5. Quick-Connect Couplings
Quick-connect fittings allow for rapid connection and disconnection of hydraulic lines without the use of tools.
- Key Benefit: Reduces downtime and simplifies maintenance.
- Variations: Single shut-off, double shut-off, and non-shut-off couplings.
Applications: Mobile equipment, industrial maintenance, and agricultural machinery.
6. Push-to-Connect Fittings
Push-to-connect fittings enable easy installation by allowing the hose or tube to be inserted directly into the fitting, where it locks into place.
- Key Feature: Tool-free connection and disconnection.
Applications: Low to medium pressure systems, pneumatic applications, and automotive systems.
7. Crimp Fittings
Crimp fittings require a crimping machine to compress the fitting onto the hose, creating a permanent connection.
- Advantages: Ideal for high-pressure systems and flexible hoses.
Applications: Hydraulic lines, oil and gas systems, and heavy machinery.
8. Bite-Type Fittings
Bite-type fittings cut into the outer surface of the tube, creating a strong grip and high-pressure seal.
- Key Feature: Suitable for use in extreme pressures and dynamic conditions.
Applications: Offshore drilling, construction equipment, and hydraulic testing rigs.
9. Barbed Fittings
Barbed fittings have ridges that grip the inside of a hose, secured with clamps or crimp sleeves.
- Advantages: Simple and cost-effective, used primarily in low-pressure applications.
Applications: Fluid transfer, irrigation, and pneumatic systems.
10. 4-Bolt Flange Fittings
4-bolt flange fittings are bolted directly to a mating surface, providing a strong seal and connection for high-pressure environments.
- Benefits: Handles high-flow rates and resists loosening under pressure.
Applications: Hydraulic pumps, cylinders, and high-flow systems.