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Seal Failure Causes


Seal Failure Causes

Possible Causes of Seal Failure

Examples of Seal Failures & Their Causes
Type of Failure Visible Condition Probable Cause Possible Cure
Hardening

HARDENING

Hardening of the dynamic face causing glazing and cracks
Heat generated by high speed Slow stroke speed Use alternative seal device

HARDENING

Hardening of the whole seal. Loss of elasticity
High fluid temperature. Deterioration of fluid. Compatibility of seal to fluid Lower oil temperature. Renew Fluid. Change to different seal compound
Wear

WEAR

Dynamic face is worn to glossy mirror-like finish
Insufficient lubrication Check oil viscosity. Use alternative seal device.

WEAR

Wear on dynamic lip is egg-shaped
Rod or piston bore not concentric Hone to within seal specs. Replace worn rod or cylinder tube.

WEAR

Abnormal wear on one side of the dynamic lip
Worn bearing or wear ring. Excessive lateral load Replace bearings. Increase bearing area.
Scarring

SCARRING

Cut or dent on the lip
Storage on a nail or peg. Improper installation tool. Store flat in a plastic bag in a closed cardboard box. Installation tools should not have sharp edges

SCARRING

Scratches on the dynamic side
Scars on the rod or bore. Foreign material in fluid. Hone, polish, and de-burr metal parts. Flush system.
Swelling

SWELLING

Material soft and misshaped
Absorption of fluid. Fluid and seal are incompatible. Water in system. Change seal compound or system fluid. Flush system.
Deterioration

DETERIORATION

Cracks and loss of elasticity. Material easily crumbles.
High fluid temperature. Exposure to ozone or sunlight. Lower oil temperature. Store seals away from sunlight and arc welding area.
Grooving

GROOVING

Axial cuts on the dynamic side
Metal chips or other foreign material in system. Imploding air bubbles. Flush system. Bleed air from system.
Extrusion

EXTRUSION

Extruded material on dynamic side of heel
Gap between mating surfaces too wide. Worn bearings. Pressure extreme. Employ back-up ring. Replace bearings. Use alternative seal.

EXTRUSION

Extruded material on static side of seal.
Uneven support surface. Undersized back-up ring. Machine surface. Correct back-up size.
Fracturing

FRACTURING

Chunks of material torn from dynamic side
Excessive back pressure Check relief valves

FRACTURING

Pressure side of seal burned and broken.
Explosion of residual air at high pressure. "Dieseling" Check maximum pressure. Bleed air from system.

FRACTURING

Long cracks in the "V" portion of the seal
Frequent high pressure shocks or spikes. Low temperature start-up Use alternative style seal. Warm system before applying pressure.

FRACTURING

Breaking off of entire dynamic side
Deterioration of material and/or fluid Use alternative material or seal. Flush system.






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