Valves are mechanical devices that control flow and pressure in a system or process. They are an important part of pipeline systems for transporting liquids, gases, steam, slurries, etc. Valves: gate valve, ball valve, ball valve, butterfly valve, check valve, diaphragm valve, pipe pinch valve, pressure reducing valve, control valve, etc. There are many types of each of these types, each with a different function and utility. Some valves are automatically operated, while others are manually operated or operated using actuators or pneumatic or hydraulic. Let air compressor accessories supplier talk to you about the various parts and valve accessories of the valve.
The functions of the valve are: stop and start the movement, reduce or increase the flow, control the movement direction, adjust the flow or process pressure, and release a certain pressure of the pipeline system.
There are many valve designs, types and styles with a wide range of industrial uses. All meet one or more of the above functions. Valves are expensive items, and it is important to specify the correct valve for the function and must be constructed of the correct material for handling the liquid.
The valve body is the first pressure divider of the valve and can resist the fluid pressure load of the connecting pipeline. It accepts inlet and outlet pipes via threaded, bolted or welded joints. The valve body ends are designed to connect the valve to a pipe or equipment nozzle through different types of end connections, such as butt or socket welds, threads or flanges. Valve bodies are cast or forged in various forms, and each component has a specific function and is constructed from materials suitable for that function.
The disc is the part that allows, throttles or suspends activity, depending on its orientation. In the case of a plug or ball valve, the disc is called the plug or ball. Disks are the third most important primary pressure divide. With the valve closed, the entire system pressure is exerted on the disk, so the disk is a pressure dependent component. Discs are generally forged, and in some designs, hard surfaces to provide excellent wear resistance. Most of the valves are named after the design of their disks.
The valve seat or sealing ring provides the disc with a seating appearance. The valve can have one or more seats. In the case of a ball or swing check valve, there is typically a seat that forms a seal with the disc to resist movement. In the case of a gate valve, there are two seats, one on the upstream side and one on the downstream side. The gate valve disc has two valve seat surfaces that touch the valve seat to form a seal for resisting movement.
In order to improve the wear resistance of the seal ring, the surface is generally hardened by welding and then machining the touch surface of the seal ring. A fine surface treatment of the seat area is necessary for a good seal when the valve is closed. The seal ring is generally not considered a pressure divider component, since the body has sufficient wall thickness to accept the programmed pressure independent of the seal ring thickness.
The cover of the valve body opening is the hood, which is the second most important divide for the pressure valve. Like valve bodies, there are many designs and types of bonnets to choose from. The bonnet is used as a cover on the valve body and is cast or forged from the same material as the valve body. It is generally attached to the body through a threaded, bolted or welded joint. In the process of making the valve, the internal components (eg stem, disc, etc.) are placed into the valve body and then the bonnet is attached to hold all the components together. In all cases, the bonnet-to-body connection is considered a pressure gap. This means that the welded joints or bolts that connect the bonnet to the body are the pressure holding parts. Valve bonnets, while a necessity for most valves, are a cause for concern. Bonnets can complicate valve manufacture, increase valve size, represent a significant cost component of valve cost, and are a source of potential leakage.
The removable and replaceable valve internals that come into contact with the active medium are collectively referred to as valve trims. These components include seats, discs, glands, gaskets, guides, bushings and internal springs. The valve body, bonnet, packing, etc. are also in contact with the active medium and are not considered valve trim. The adjustment function of the valve depends on the disk and seat interface and the relationship of the disk orientation to the seat. Due to the decoration, basic movement and flow manipulation are possible. In a rotary motion fitout plan, the disc slides tightly over the seat to create a change in the active opening. In a linear motion trim design, the pan is raised vertically away from the seat, presenting an annular hole. Valve fittings can be constructed from a variety of materials, as different properties are required to withstand different forces and conditions. Bushings and packing glands are not subject to the same forces and conditions as discs and seats. Active media properties, chemical composition, pressure, temperature, flow rate, velocity and viscosity are some of the important considerations in choosing the right finishing material. The trim material may or may not be the same material as the valve body or bonnet.