Spiral FailureFailure Pattern: Generally found on long stroke, hydraulic piston seals, the surface of the O-ring exhibits a series of deep, spiral 45 degree angle cuts. Problem Sources: Caused when some segments of the O-ring slide while other segments simultaneously roll. At a single point on its periphery, the O-ring gets caught on an eccentric component, or against the cylinder wall, causing twisting and development of 45 degree angle, surface cuts. Contributing Conditions Include: Eccentric components... Wide clearance combined with side loads... Uneven surface finishes... Inadequate lubrication... Excessive O-ring material softness... Too slow stroke speeds. Suggested Solutions: Check for out-of-round cylinder bore...Decrease clearance gap... Machine metal surfaces to 10-20 micro-inch finish... Improve lubrication (consider internally-lubed O-rings)... Increase O-ring material hardness and/or cross section... Employ anti-extrusion back-up rings. 
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