Three-Way Valve Incident - ejected stem during changeout of Duplex Filter

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Average: 4 (2 votes)
Alert ID: 
Description of Process: 
Three way valve on the lube oil system is designed to permit change out of duplex filter whilst the system remains online.
Description of Incident: 

Operation technicians were attempting to change filter banks by operating a three way valve. In act of trying to “loosen” the valve, the pin through the shaft had sheared and the lifting jack nut backed out to the point where the threads were no longer sufficiently engaged. Pressure within overcame any remaining hold on the stem from the packing, and the stem and oil was ejected.

Good Practice Guidance: 
Immediate controls implemented to isolate equivalent valves. 

Valve operating instructions shared among operations and maintenance teams to ensure valve is set up, operated and maintained in the correct manner.


Causes and consequences of incident or accident: 
Moving, flying or falling object
Uncontrolled release of a flammable gas or liquid
Cause and consequence of incident or accident, if not listed above: 
Mechanical failure. Requirement for improved understanding of three-way valve design, function and operation.
Contributing factor: 
Change management
Control of work