O-Ring Failures

Below is a list of typical failures for o-rings. This is by no means a complete list of possible failures. If you are experiencing o-ring failures in your application, ERIKS technical services team can help diagnose and reccommend a solution. Contact us for help.

EXTRUSION AND NIBBLING Failures due to extrusion and nibbling are usually associated with dynamic rod or piston seals, but can also occur with a static application with pressure pulsations.
	Causes: Clearance is too largef Too large of a seal selected System pressure is too high Increase in clearance gaps due to excessive system pressure Incorrect material (too soft) Corners of gland are too sharp	Prevention: Closer metal fits Reduce machining tolerances Use backup rings Increase hardness of seal Correctly size seal Break edges of gland
SPIRAL FAILURE Spiral failures are usually associated with long stroke piston seals, but can also occur with dynamic rod seals. The seal will exhibit a deep spiral cut (usually about 45°) into the cross section.
	Causes: Segments of the o-ring slide while other parts roll simultaneously Inadequate or improper lubrication Improper o-ring installation (pinched) A portion of the seal hangs up or gets pinched No uniform surface finish	Prevention: Improve surface finish Improve lubrication Change cross section of seal Use backup rings
ABRASION Failures associated with abrasion are usually associated with dynamic applications. The seal with have a flat area on one side of the cross-section where the moving contact is made and can also show wear lines parallel to the direction of motion.
	Causes: Too rough or too smooth metal surface Poor lubrication Excessive temperatures Fluid contamination	Prevention: Use recommended surface finish Provide adequate lubrication Select correct material Use a material with a higher abrasion resistance Eliminate fluid contamination
COMPRESSION SET Compression set failures can occur in both dynamic and static applications and are characterized by a flat area on both sides of the seal cross-section in the area being squeezed.
	Causes: Temperature too high Operating temperature Operating temperature + frictional heat Gland overfill (improper gland design) Volume swell Excessive squeeze Material with poor compression set properties	Prevention: Select correct material (compatible with fluid and compatible with temperature) Evaluate squeeze on seal Examine gland dimensions Reduce system temperature Use a material with a low compression set
WEATHER OR OZONE CRACKING SET Failures associated with weather or ozone cracking normally occur in both dynamic and static applications under stress and exposed to ozone and are characterized by many small cracks perpendicular to the direction of stress.
	Causes: Ozone attacks and breaks the double bond points in a polymer chain of some polymers	Prevention: Select correct material Change storage conditions
INSTALLATION DAMAGE Failures associated with installation damage occur in both dynamic and static applications.
	Causes: Inproper use of installation tools Sharp corners on mating parts and threads Insufficient lead-in chamfer Too large/too small sized seal Incorrect gland dimensions	Prevention: Change dimensions of metal components to eliminate pinching of seals Use lead-in chamfers ~20° Break sharp corners Use installation tool correctly
CHEMICAL DEGRADATION Failures associated with chemical degradation occur in both dynamic and static applications and may be characterizied by blisters, cracks, voids or discoloration.
	Causes: Inproper material selection	Prevention: Select correct material
EXPLOSIVE DECOMPRESSION Explosive decompression failures occur with the sbsorption of gas at high pressure and the subsequent rapid decrease in pressure causing the absorbed gas to blister and rupture the seal as the pressure is rapidly removed. With this type of failure, the seal can exhibit blister, pits or pocks on the surface.
	Causes: Absorption of gas or liquiefied gas under pressure with lack of escape on decompression	Prevention: Increase time lapse for decompression Use higher modulus rubber or other materials that will resist rupture