The operating parts of a valve which are normally exposed to the process fluid are referred to as 'valve trim'. Usually these parts are subject to wear and degradation and hence are replaceable. Usually parts like stem, closure member, seating surface etc. are called as valve trim. The parts such as body, bonnet, yoke etc. are not considered as trim.
Following table represents a list of parts, which can be considered as trim for different types of valves.
|Type of Valves||Valve Trim|
|Angle Valves||Stem, Seat, Disc, Disc nut, back-seat bushing|
|Disc Valves||Disc, Disc nut, back-seat bushing|
|Gate Valves||Stem, Seat, wedge, back-seat bushing|
|Globe Valves||Stem, Seat, Disc, Disc nut, back-seat bushing|
|Lift type check Valves||Seat ring, Disc, Disc guide|
|Swing type check Valves||Seat ring, Disc, Disc holder, Disc holder pin, Disc nut, Disc nut pin, side plug, carrier pin|