18” Metaltite ball valve (full-bore, fail-close), from KTM, cannot be operated (cannot command to open), even though the equalize valve was already opened and the differential pressure across the valve was already 0 bard. Please be noted that there was no fault in actuator system. Normally, this valve is always left open, while its operating condition (gas pressure) is around 70 barg. However, when we tried to reduce some gas pressure, we found that this valve can be opened. After checking and comparing with other valve with the same size and type (also same actuator type), we found that some valves have tubing connection from the valve’s drain port to one side of differential pressure transmitter (low-pressure side). Tyco/KTM valve with Metaltite seats- no luck there. Nothing about a balancing port on their web page. If anything, pressure trapped inside the cavity should UNLOAD the seat(s). I'm thinking JLS has a pretty valid guess that the valve is just seized. Max pressure in the actuator, some big-strong guys, >pushing< on a big cheater bar. ( Use appropriate care: Don't let anybody get in front of it 'cause once the valve starts to move it will likely go fast and it could cause an ouchie.)

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