English 
Chinese 
Hydraulic cylinder seal is important in construction industry. Let’s explore the reasons why seals fail and how to prevent it.
I.Reasons for seal failure
1.Failure due to seal design
Unsuitable material selection (chemical resistance, temperature resistance, etc.)
Unreasonable structural design (pressure, low temperature, overload, etc.)
Unsuitable gap and tolerance
Unreasonable product selection (single-acting, double-acting, pressure retention requirements, etc.)
2.Seal application leading to failure
Excessive system pressure
Application temperature too high or too low (temperature failure, aging)
Surface roughness, oil contaminants
Transient overload
Damage due to faulty installation
II.Hydraulic cylinder seal failure and preventive measures
Phenomenon (1): Mechanical damage
Causes:
1.Scars on the mating surface
2.Containing metallic debris or other impurities.
3.Burrs on the chamfer of the mating surface during assembly.
Preventive measures:
Thoroughly check before assembly, clean the parts, do not allow any impurities into the
Improve the system filtration device, and replace the system medium on time.
Increase the chamfer of the mating surface, and make it as smooth as possible, remove burrs and flying edges
Phenomenon (2): extrusion
Causes:
Matching gap design is too large
System pressure is too high
Support ring rigidity is not enough to produce clearance
Preventive measures:
Reduce the fit clearance
Add support ring
Pressure is too high, you can add a buffer seal
Re-select the sealing material. Different materials suit for different situation. For more seals, click here to check more.
Change the support ring material or size
Phenomenon (3): scorching
Cause:
Residual air in the system during operation, the air in the seal gathering compression and warming to produce the seal burnt carbonization
Preventive measures:
1.Before starting the cylinder, exhaust the air in the cylinder as much as possible.
2.When the cylinder starts, do not drive to high speed immediately.
3.Add grease to the valley of the U-ring when it is used to prevent air from accumulating.
Phenomenon (4): Hardening
Cause:
The temperature is too high
The medium and rubber materials are not compatible
Media deterioration
Seal moisture or exposure in the air for too long than the stock period leading to material aging.
Preventive measures:
Reduce the temperature, or change the high-temperature-resistant seal materials like 1148290 seal kit for CAT 312.
Change the medium or change the seal material that is resistant to the medium.
Change to new medium
Do not expose the seals to the atmosphere for a long time, in strict accordance with the requirements of the seal inventory seal preservation
Phenomenon (5): torsion
Causes:
Movement speed is too fast
There is eccentric movement
Uneven roughness of sliding surface
Installation torsion
Preventive measures:
Change to lip seal
Eliminate eccentric movement
Modify the roughness of the sliding surface
Pay attention to the installation
In summary, the causes mentioned above are just a partial of all. To prevent seal failures, you can ask specialist for help according to the situation.