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Coker Blocked In Furnace Incident Investigations and Preventative Measures

Presented By

Dale Wilborn - Chevron & AMPO Poyam Valves

Clay Vender Werff - Chevron & AMPO Poyam Valves

David Swensen - Chevron & AMPO Poyam Valves


A blocked Coker furnace outlet flow path is one of the most serious and relatively frequent incidents. The Salt Lake Coker experienced this situation last year; the root cause was a mechanical failure of a component in the resid isolation valve operator (or gearbox).

Even with Coker Structure Interlocks, the industry is still experiencing blocks in situations. The reason is the Interlocks program uses MOV motor turns to determine the open or closed valve position. If there is some mechanical damage or failure between the motor and the valve stem, the valve position will be false. The safety interlocks will give the operator permission to proceed even though the system is not in the required posture to rotate the switch valve.

This vulnerability can apply to a wide number of valve types or the switch valve in-self. We will examine types on MOV component failure, operator field verification steps, and potential for a future 2nd independent electronic valve position indication.

Online monitoring and predictive measurements to identify the problem before failure are desired. This is something that Chevron has not fully developed yet and would be interested in hearing if torque, amps, vibration or other types of monitoring is being used in the industry to prevent unplanned failures.

The Delayed Coker structure is extremely challenging for MOV reliability due to heat, stream quality, the need for steam purges, and the high frequency of valve movement compared to other refinery technologies. Delayed Coker units have made great progress with Structure Interlocks but more work is required to provide the needed level of safety.

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