Although there are many different classifications of valves specific to their respective functions, there are standard parts or components of valves you may find regardless of the classification. They are the valve body, bonnet, trim, seat, stem, actuator, and packing.
The Valve Body is the primary boundary of a pressure valve which serves as the framework for the entire valve’s assembly. The body resists fluid pressure loads from connected inlet and outlet piping; the piping is connected through threaded, bolted, or welded joints.
The Valve Bonnet is the opening of the Valve Body’s cover. Bonnets can vary in design and model, is built using the same material as the Valve Body, and is also connected to the entire assembly through threaded, bolted, or welded joints.
The Valve Trim collectively refers to all the replaceable parts in a valve, e.g. the disk, seat, stem, and sleeves––all of which guide the stem as well.
The Valve Disk allows the passage or stoppage of flow. Disks provide reliable wear properties and differ in what they look like per valve type. For example, in the case of a ball valve, the disk is called a ball, whereas for a plug valve it is a plug.
The Valve Seat(s) or its seal rings provide surface seating for the disk. For example, a globe valve requires only one seat and this seat forms a seal with the disk to stop the flow.
The Valve Stem provides the proper position which will allow the opening and closing movement of the Valve Disk. Therefore, it is connected to the Valve Disk on one end and the Valve Hand Wheel or the Valve Actuator on the other.
The Valve Yoke is the final piece in the valve’s assembly; the Yoke connects the Valve Bonnet with the actuating mechanism. The Valve Stem passes through the top of the Yoke which holds the Yoke or stem nut.
There are countless variants of valve designs, sizes, and configurations. These basic parts will be found in most, but the particular form and arrangement of the part may provide an advantage when employed for a particular application. Share your industrial process valve requirements and challenges with a valve specialist. Combine your own process knowledge and experience with their product application expertise to develop an effective solution.