The strength of the pressure O-ring The strength of the pressure O-ring johncaboth (Mechanical) (OP) 6 Feb 15 05:19 What contact pressure passes the rubber ring when the fluid pressure on it? RE: The strength of the pressure O-ring btrueblood (Mechanical) 6 Feb 15 15:25 If you are looking to do a hydro-test calc., assume the o-ring essentially fills the groove, i.e. the contained pressure is felt at all groove surfaces. RE: The strength of the pressure O-ring Compositepro (Chemical) 6 Feb 15 19:08 Your question is very vague. There is a gradient in contact pressure depending on location on the o-ring. The only requirement for a good seal is that the peak contact pressure is greater than the fluid pressure. In a well designed seal the average contact pressure is not much greater than the fluid pressure.