Hydraulic hose fittings are essential components in a variety of systems, playing a crucial role in connecting hydraulic hoses to other components. They are widely used across numerous industries, including manufacturing, water and sewage systems, oil refineries, chemical processing, marine & shipbuilding, aerospace and construction.
Types of Hydraulic Hose Fittings
There are several types of hydraulic hose fittings, each designed for specific purposes. They vary in size, material, seal type, and temperature and pressure tolerances. Some fittings control the flow of fluid, either allowing or preventing it, and others can do both. The effectiveness of a hydraulic hose fitting lies in its ability to create a secure seal.
Key Types: Crimped and Field Attachable Fittings
- Crimped Fittings: These are permanent fittings sealed with a crimping machine. They offer high security but require specific equipment for installation.


2. Field Attachable Fittings: These can be installed without a crimper, using a socket and nipple, making them versatile for various settings.

Materials Used in Hydraulic Hose Fittings
Hydraulic fittings are made from different materials, each suitable for specific applications:
- Carbon Steel Hose Fittings: Made from steel alloys, these fittings are durable and can withstand extreme temperatures.
- Stainless Steel Hydraulic Hose Fittings: Ideal for highly corrosive environments and can endure very high temperatures and pressures. They are, however, more expensive.
- Brass Hose Fittings: Provide a tight seal and meet various industry standards, suitable for moderate temperatures and pressures.
- Aluminium Hose Fittings: Lighter and corrosion-resistant, these are less common but useful in certain applications like automotive hydraulics.
How To Identify Hydraulic Hose Fittings
To properly identify the hydraulic hose fitting for the application, determine the type of fitting, match the port connection with that of the hose, and determine the type of seal and fitting design and size of the thread.
- Determine the type of fitting – check to see if the fitting is crimped or reusable. Newer equipment and connections are usually crimped.
- Match the port connection with that of the hose – another important part is to make sure that the port connection matches the one on the hydraulic hose. Refer to the table below.

- Determine the type of seal – referring to the physical dimensions and technical characteristics, identify whether it is using an O-Ring, a Mated Angle, or a Tapered Thread. Mated Angles are based on straight and parallel thread types, in which the male and female units will form the seal. Tapered Threads will have the threads on the outside if it is a male unit and on the inside if it is female. Lastly, O-Rings (ORFS) will already include the seal.
- Determine the fitting design and size of the thread – refer to the list below for the most common and widely used hydraulic fittings.
- NPT/NPTF – this is the most commonly used type of threads in North America and is recognisable by its tapered inner diameter and outer diameter. This creates a self-sealing fitting.
- BSP(BSPP and BSPT) – also known as the British Thread Type, is standard fittings adopted internationally for making connections and sealing pipe ends.
- SAE Straight Thread – a thread type known for its reliability and reusability-has excellent sealing due to its O-rings. FKM and NBR O-ring are most commonly used in hydraulic applications.
- ISO 6149 – this is equipped with a straight thread O-ring port, useful for diagnostic port applications.
- JIS-B2351 – this thread type is primarily used as a hose adapter for equipment manufactured in Japan or Korea. These usually come with BSP threads.
- DIN Metric – Since this thread type uses the German Industrial Standard, they are popular throughout Germany and the majority of Europe.
- 4-Bolt Flange – these come in a variety of types, catering to either standard or heavy-duty applications.
How Do You Choose the End Fittings For a Hydraulic Hose?
- Size: It’s crucial to match the internal and external diameters of the fittings with the hydraulic hose. Incorrect sizing can lead to poor sealing and potential leaks or failures.
- Material: The material of the fittings should be compatible with the hydraulic fluid and the working environment. Common choices include brass, aluminum, steel, and stainless steel. O-rings, often made from NBR (Nitrile), are a typical sealing material.
- Temperature: Choose fittings that can withstand the operating temperatures of your system. The material composition of the fittings plays a significant role here.
- Pressure: Ensure the fittings can handle the specific pressure range of your application. Exceeding the rated pressure can lead to leaks or hazardous situations.
- Application: The type of fitting depends on its use, whether for mixing or distributing. Options like T-shaped or cross-shaped fittings might be relevant.
- Assembly: If frequent connections and disconnections are required, quick-connect fittings are advisable. Hydraulic compression fittings, which use a compression nut and ferrule, can eliminate the need for welding or soldering.
- Permanence: Decide if you need a permanent or removable fitting. Field-attachable fittings are suitable for frequent changes, while crimping machines offer a more permanent solution.
Consider the type of hydraulic fluid (petroleum-based, water-based, or synthetic) as it affects fitting compatibility.
Installing Hydraulic Hose Fittings
- Choose the correct hose type and size, cutting it neatly to length.
- Select the fitting based on size, temperature, pressure, style, material, orientation, and fluid type.
- Mark the insertion depth on the hose, lubricate if necessary, and insert the hose into the fitting.
- Use a hydraulic crimper, set to the fitting’s diameter, for crimping. Refer to a crimp chart for guidance.
- Clean the hose assembly to prevent contamination.
Sealing Hydraulic Fittings
Hydraulic fittings are usually sealed with O-rings, thread sealants, or self-sealing mechanisms like SAE fared and flanged fittings. Manual sealing is not typically required.
Use of Teflon Tape
Teflon tape is not recommended for hydraulic fittings as they are designed to seal through O-rings, metal face seals, or threads. Leaks generally indicate incorrect usage or connection rather than a need for additional sealing materials.
Conclusion
Hydraulic fittings are integral to the functioning of various industrial systems. Choosing the right type, material, and installation method is key to ensuring efficiency, safety, and longevity of the hydraulic system. With a range of options available, understanding the specific requirements of your application is crucial.
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