Measurements of Contact and Leakage in a Pipe Flange Gasket

Leakage from gaskets and seals is a major concern in the process industry. In this work we investigate an ultrasonic means of determining the degree of contact between a pipe flange and compressed gasket. This is related to the leakage rate through the gasket. A simple pressure vessel with a flange and gasket assembly has been constructed. Ultrasonic transducers were mounted on the flange. Reflected pulses and leakage rates were monitored simultaneously for a range of gasket contact pressures and internal pressures. The reflected ultrasonic wave can be used to determine the stiffness of the gasket-flange interface. Interface stiffness was found to correlate closely with the applied gasket clamping load. In this way the ultrasonic signal could be correlated with leakage rate.