Design review and predictive maintenance using ultrasonic techniques on swing check valves

Failure of swing check valves during normal operation prompted the development of a simple, yet effective in-plant test for measuring and recording the operating characteristics of swing check valves. A major cause of failure has been excessive wear of the hinge pin, hinge pin bushings and disc stud, caused by disc oscillations such as free flutter. In addition, disc tapping at the backstop leads to fracturing of the disc stud. In the past, theoretical formulas were derived to determine the correct flow velocities for minimizing disc oscillations in swing check valves. A system is now available to measure and quantify the actual instability during in-plant testing under all operating flow velocities. With proper use of this equipment, potential problem valves are identified based on their actual operating characteristics making it possible to implement design changes or maintenance prior to failure