Order this important seat leakage set and save on FCI 70-2-2013 and 70-3-2016 FCI 70-2-2013: This standard establishes six classes of seat leakage for control valves. Also defined are specific test procedures to determine the appropriate class. Included are classes commonly associated with double-port, double-seat or balanced single-port control valves with a piston ring seal or metal-to-metal seats; commercial unbalanced single-port, single-seat and balanced single-port valves with extra tight piston rings or other sealing means and metal-to-metal seats; valves for critical applications where the control valve may be required to be closed, without a blocking valve, for long period of time; and resilient seating control valves with "O" rings or similar gapless seals, among others. FCI 70-3-2016: The standard applies to pilot operated and direct acting pressure reducing, pressure relieving (back pressure), differential pressure and temperature regulators. The FCI has periodically updated the standard since the standard's development in 2001. Responding to the industry's request, the FCI has recently updated the standard to include Class VIII, which is a "no permissible leakage" or "bubble tight" standard generally associated with resilient seating regulators either balanced or unbalanced with "O" rings or other gapless seals.