From Stem to Seat: An In-Depth Look at the Different Parts of a Valve

Valves are essential components used in a wide range of industries to control the flow of fluids, gases, or other substances. They consist of various parts that work together to regulate, start, or stop the flow. Let's take an in-depth look at the different parts of a valve:

1. Body: The valve body serves as the main outer casing that houses the internal components. It provides the structural integrity and connection points for attaching the valve to the pipeline or system. The body is typically made of materials such as brass, cast iron, stainless steel, or other suitable alloys, depending on the application and fluid being controlled.

2. Bonnet: The bonnet is the cover or top portion of the valve that protects the internal parts and provides a seal. It is usually bolted or screwed onto the valve body. In some cases, the bonnet also houses components like the stem, packing, and actuator. The design of the bonnet can vary based on the type of valve and its operating conditions.

3. Disc or Closure Element: The disc, also known as the closure element, is the component that moves inside the valve body to open, close, or regulate the flow. It can take different forms depending on the valve type, such as a gate, ball, plug, butterfly, or globe. The disc is typically connected to the valve stem and is responsible for controlling the fluid flow through the valve.

4. Stem: The stem is a rod-like component that connects the actuator (if present) to the disc. It transmits the motion or force from the actuator to open or close the valve. The stem extends through the bonnet and often has a packing arrangement to prevent leakage around the stem. In some valves, the stem may have additional features like a handle or handwheel for manual operation.


Stainless Steel Stem