Updated: Nov 20, 2020

In this article, we will learn part of the sliding stem control valve used in the process industry extensively.

A sliding stem type control valve actuates in linear motion. A stem comes with a single port or double port arrangement.

Single port means it has only one plug is there to restrict the flow of the fluid and double port means it has two plugs to throttle the flow of the fluid.

Sliding stem type of valve has a travel length of less than 3/4" except in some case it has a travel length requirement of more than 3/4".

Have a look into the below figure to know the difference between two assemblies.

You can clearly see the difference between a single port and a double port control valve assembly.

Now have a look at the different internal parts of the sliding stem control valve.

Let learn about each part definition of the sliding stem valve:

1. valve plug stem: It connects the plug with the actuator part and provide strength to the actuator.

2. Packing Flange: It compresses the stud bolt to make the gland packing tight and prevent the process leak.

3. Actuator Yoke Nut: Used to connect the actuator and the valve body stem.

4. Packing: It prevents leakage of the process from the valve body.

5. Bonnet: It supports the position of the plug and prevent it to move left and right.

6. Valve plug: It is the main part of a valve body which is used to restrict the flow of the fluid.

7. Cage: Used to reduce cavitation by reducing the pressure drop around the valve body.

8. Seat ring gasket: It is used to support the seat.

9. Valve body: It comprises of the valve plug, trim and valve seat.

Mainly the control valve consists of two-part. One is a valve actuator and the second one is the valve body.

A valve actuator provides a thrust to move the valve body to control the flow of the fluid.

Valve body consists assembly in which it contains plug to throttle the flow of the fluid. It also contains a seat on which plug seat and also a trim part.

You can check out the article on control valve body and actuator by clicking on the same word.

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