Prediction of Extrusion Failures of O-Ring Seals

Abstract

It is generally recommended by most manufacturers to keep working pressures of O-ring seals below 10 MPa (20 MPa with backup rings) and clearances below 0.15 mm, or else they might fail by extrusion. For many applications, and especially for large one-shot impact devices, these limits are much too low, and more realistic limits may be set through better understanding of the failure modes. A theoretical analysis of the O-ring elastic and plastic extrusion process is developed and test results up to 350 MPa are shown to support the analysis. The resulting extrusion fail-loads are examined as function of seal geometry, material properties, and load rates. Some design recommendations and further research efforts are discussed.