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.

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