Packing Adjustments and Maintenance
Ball valves are packed valves and all packed valves have plastic (PFA, PTFE, PEEKTM, PCTFE, etc.) components to maintain a seal along the stem shaft
to isolate the media from the atmosphere. Stem shafts on packed
valves are dynamic, which means the shaft-to-packing seal is
constantly moving. All plastics cold flow and distort affecting their
sealing ability, particularly in high duty-cycle applications, thermal
cycling, and at elevated temperatures. If an actuated ball valve
cycles more frequently than a manual one, it will require more
packing adjustments.
Frequency of packing adjustments and maintenance procedures
directly impact cost of ownership.