A Comparative Evaluation of Square VS Round Cross-Section Circular Seals Using Stress Relaxation Data to Predict the Useful Life of a Seal

Nitrile, silicone and fluorocarbon polymers were evaluated in square and round cross-section rings using stress relaxation to determine retained sealing force under static conditions at elevated temperatures. Stress-relaxation data were combined with a stress-decay formulation to predict the life of the seals while examining the effect that squeeze, cross-sectional shape, and state of cure have on performance.

Regardless of material used, square cross-section rings exert a greater sealing force than their round counterparts for a longer time period. This improvement in seal life is due to cross-sectional shape and state of cure.