Modeling of an Actuator Stem Failure

Problem Description
–An actuator stem that operates a gate valve in an MTBE line in a petrochemical plant has failed.
–This hydraulically powered actuator is used to open and close the valve in a specific pattern.
–Visual inspection revealed a penetration mark on the opposite flange face caused by a too long coupling stud at the end of each opening sequence of the valve. This coupling connects the actuator stem to the valve stem.
–Ansys Workbench is used to perform stress and fatigue analyses to determine the fatigue life.
–Fatigue analysis is needed to identify the maintenance period in which the oversized stud was installed.

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