Possible Causes of Seal Failure

Examples of Seal Failures & Their Causes
Type of Failure	Visible Condition	Probable Cause	Possible Cure
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	Dynamic face is worn to glossy mirror-like finish	Insufficient lubrication	Check oil viscosity. Use alternative seal device.
	Wear on dynamic lip is egg-shaped	Rod or piston bore not concentric	Hone to within seal specs. Replace worn rod or cylinder tube.
	Abnormal wear on one side of the dynamic lip	Worn bearing or wear ring. Excessive lateral load	Replace bearings. Increase bearing area.
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	Material soft and misshaped	Absorption of fluid. Fluid and seal are incompatible. Water in system.	Change seal compound or system fluid. Flush system.
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	Axial cuts on the dynamic side	Metal chips or other foreign material in system. Imploding air bubbles.	Flush system. Bleed air from system.
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	Chunks of material torn from dynamic side	Excessive back pressure	Check relief valves
	Pressure side of seal burned and broken.	Explosion of residual air at high pressure. "Dieseling"	Check maximum pressure. Bleed air from system.
	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.
	Breaking off of entire dynamic side	Deterioration of material and/or fluid	Use alternative material or seal. Flush system.