hydraulic crimp fittings

Hydraulic crimp fittings are the key parts of the hydraulic system used to connect the hose and pipe or hydraulic components, with reliable sealing, strong vibration resistance, high pressure resistance and other characteristics, widely used in construction machinery, mining equipment, agricultural machinery and other fields.

Meaning and Core Advantages of Hydraulic Crimp Fittings

Hydraulic Crimp Fittings is a kind of special buckling tool to tightly press the outer layer of the coupling jacket and the hose. Hydraulic Crimp Fittings are non-welded fittings that are tightly compressed between the fitting jacket and the outer layer of the hose by means of a special buckling tool, and are mainly composed of a fitting core, a fitting jacket, and a hose. Its core advantages include:
1. High sealing: mechanical buckling to form a multi-layer sealing structure, with a pressure resistance of up to 3570MPa, suitable for high-pressure, high-impact scenarios;
2. Vibration-resistant performance: the buckling process makes the hose and the coupling tightly bonded to reduce the risk of vibration-induced leakage;
3. No need to weld: avoiding deformation of the material caused by welding or contamination, especially suitable for the transmission of flammable media, such as oil, gas, etc.;
4. Rapid installation: standardized buckling process significantly improves installation efficiency and reduces maintenance costs.

What are the common types of hydraulic crimp fittings

Welded hydraulic crimp fittings:

This type of fittings connects the pipe to the fitting body by welding, which is a strong connection and reliable sealing. However, the disadvantage is that it needs to be welded during assembly, which increases the workload and requires the use of thick-walled steel tubes.

Ferrule hydraulic crimp fittings:

ferrule fittings have a simple structure, including the fitting body, ferrule and compression nut. When the nut is tightened, the ferrule deforms and forms a seal with the tapered surface of the joint body, while the inner edge of the ferrule is embedded in the outer wall of the oil pipe to realize the seal. This kind of joint does not need welding, easy to install, suitable for medium and high pressure system.

Flared hydraulic crimp fittings:

are divided into A-type and B-type two structures, through the end of the tube is pre-made into a flared shape, and then placed in the fitting body of the outer cone and the tube sleeve (or B-type nut) between the inner cone, tighten the nut to make the tube’s flared mouth under pressure, to achieve sealing. Suitable for low and medium pressure system, simple structure, easy to use.

HOSE HYDRATIC CRIMP FITTINGS:

Specialized for connecting hoses, usually consisting of a metal sleeve, a rubber washer and a wire-wound tube. The hose is held in place by the compression sleeve, keeping it connected to other components. Buckling hose couplings are easy to install and are suitable for low pressure hydraulic systems or industrial applications.

Rigid hose hydraulic crimp fittings:

are suitable for rigid hose connections and consist of a sleeve, nut, front fitting and gasket. By pressing the sleeve and front fitting inward to a certain position to form a seal, ensuring the stability of the connection and sealing of high-pressure systems.

Clip-on hydraulic crimp fittings:

Compact and easy to install, consisting of a connection body, inner cavity sleeve, clamping ring and sealing gasket. Easy to disassemble, repair and replace, especially suitable for highly centralized pipeline connection, widely used in metallurgy, steel, shipbuilding, machinery manufacturing and other industries.

Extruded hydraulic crimp fittings:

The tight connection is realized by extruding the fittings together with the tubes in an extruder, which deforms the fittings under the force. Simple installation, high pressure resistance, high reliability, widely used.

Rotary hydraulic crimp fittings:

Includes the main body, sleeve, front fittings and seals. The fixing of the tube is accomplished by rotating the sleeve, while the sealing effect is realized by the front end fittings and sealing ring. Suitable for high-pressure hydraulic system and pipeline connection under special working environment.

How to identify high quality Hydraulic Crimp Fittings

1. Material and marking

Material marking: regular products are marked with hose type (e.g., SAE 100R2AT), pressure resistance level (e.g., 35MPa) and production standard (e.g., ISO 18752);
Surface treatment: the outer sleeve of the fitting should be free of cracks and corrosion, and the carbon steel material needs to be zinc-plated or phosphated, while the stainless steel material should be smooth and non-magnetic (austenitic). The surface is smooth and non-magnetic (austenitic 304/316L).

2. Structural characteristic

Buckling uniformity: observe the combination of the hose and fitting after buckling, there should be no local depression or bulge;
Seal integrity: the rubber layer inside the hose and the contact surface of the fitting core should be tightly adhered to, with no air bubbles or gaps.

3. Certificates

Suppliers are required to provide ISO 9001 quality certification, pressure resistance test reports and material certificates (e.g. stainless steel composition analysis report).

Installation specification of Hydraulic Crimp Fittings

1. Preparation before installation

Hose cutting: Use special pipe cutter to cut the hose, make sure the verticality error of the end face is ≤0.5°, and remove the internal and external burrs;
Cleaning: Use alcohol or high-pressure gas to remove the internal impurities of the hose to avoid contaminating the hydraulic oil.

2. Buckling procedure

1. Pre-assembled coupling: insert the coupling core into the hose, and the outer sleeve into the outer layer of the hose;
2. Buckling positioning: use the special buckling machine to adjust the size of the mold to ensure that the buckling pressure is uniform (reference standard: buckling amount is generally 58% of the outside diameter of the hose);
3. Pressure calibration: set the buckling pressure according to the specifications of the hose (e.g., φ25mm hose requires 2025 tons of pressure), to avoid over-compression resulting in the rupture of the hose. Pressure calibration: set the buckling pressure according to the hose specification (e.g. φ25mm hose needs 2025 tons pressure) to avoid over-compression leading to hose rupture.

3. Post-installation test

Sealability test: Pass 1.5 times the working pressure fluid, hold pressure for 5 minutes, check for no leakage;
Appearance check: Make sure that there is no crack or deformation in the buckling part, and that there is no relative sliding between the hose and the joint. 4.

4. Attention

Prohibit secondary buckling: the buckled joints should not be adjusted repeatedly, otherwise the sealing will be reduced;
Environmental suitability: in high temperature or corrosive environments, it is necessary to choose the corresponding weather-resistant fittings;
Regular maintenance: check the buckling part every six months to see if it is loose, and replace the aging hose in a timely manner.

Conclusion:

Hydraulic Crimp Fittings have become an indispensable connection component in modern hydraulic systems due to their high strength, easy installation and long life. Correct selection and standardized installation can greatly enhance the stability and safety of the system. For special applications (e.g. ultra-high pressure or extreme temperatures), we recommend contacting our engineers for a free customized solution.

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