Fixedcone (HowellBunger) valves have been in wide use for many years for flow control. These valves may face different types of damages and failures due to vibrational stresses during operation. In this study, a number of modal analyses of a HowellBunger (DN: 1000 mm) valve made by Mechanic AB Co, are conducted using the Finite Element Method (COSMOS/Works) and its natural frequencies with vibrational mode shapes in five cases including fullyopened, 20%, 40%,and 80% opening conditions were determined, then, the dimensionless coefficient "Mercer" was obtained for the valve. The result showed that the operating point of the valve is the flow rate of16 m3/s and valve opening degree of 40%, in this case due to reinforcement resulted from moving shell, the structure strength against vibration increases and as a result, natural frequency increases as well.
Failure, HowellBunger valve, Modal analysis, Natural frequency
