Trim Parts in a valve

Dear Rajkumar

Its a normal understanding that all wetted parts come under trim . . .

If you take above statement correct then even body , bonnet, disc should also come under trim. . . which is not so

Trim basically consist consist of those parts which undergo some sought of rubbing action . . . eg. body seat, disc seat, stem and backseat.

If you observe these are the only part which undergo wear either because of rubbing or erosion due to fluid flow. thats why these parts are normally made harder than other parts of valve.

In nutshell Trim are parts with higher hardness to sustain wear / erosion

KAILASH GAEKWAD

• Valve Trim
• The internal elements of a valve are collectively referred to as a valve's trim. The trim typically includes a disk, seat, stem, and sleeves needed to guide the stem. A valve's performance is determined by the disk and seat interface and the relation of the disk position to the seat. Because of the trim, basic motions and flow control are possible. In rotational motion trim designs, the disk slides closely past the seat to produce a change in flow opening. In linear motion trim designs, the disk lifts perpendicularly away from the seat so that an annular orifice appears.

Dear Raj

ANSI/ISA-S75.05-1983 "Control Valve Terminology" defines trim as "the internal parts of a valve which are in flowing contact with the controled fluid".

The Control Valve Handbook edited by Fisher is more specific and define trim as "the internal components of a valve that modulates the flow of the controlled fluid. In a globe valve body, trim would tipically include closure member (plug), seat ring, cage, stem and stem pin".

Cashco has a broader definition and "includes all the parts that are in flowing contact with the process fluid except the body flanges and gaskets. The plug, seats, stem, guides, bushings and cage are some of the parts included in the term trim".