Control Valves body and Basic Parts of Control Valves

 Control Valves body

Valve Body

The body, sometimes called the shell, is the primary pressure boundary of a valve. It serves as the principal element of a valve assembly because it is the framework that holds everything together.

The body, the first pressure boundary of a valve, resists fluid pressure loads from connecting piping. It receives inlet and outlet piping through threaded, bolted, or welded joints.

Valve bodies are cast or forged into a variety of shapes. Although a sphere or a cylinder would theoretically be the most economical shape to resist fluid pressure when a valve is open, there are many other considerations.

For example, many valves require a partition across the valve body to support the seat opening, which is the throttling orifice. With the valve closed, loading on the body is difficult to determine. The valve end connections also distort loads on a simple sphere and more complicated shapes.

Ease of manufacture, assembly, and costs are additional important considerations. Hence, the basic form of a valve body typically is not spherical, but ranges from simple block shapes to highly complex shapes in which the bonnet, a removable piece to make assembly possible, forms part of the pressure-resisting body.

Narrowing of the fluid passage (venturi effect) is also a common method for reducing the overall size and cost of a valve. In other instances, large ends are added to the valve for connection into a larger line.

Control Valve Body materials

The control valve user normally specifies the body material. Which is often the same material as the pipe. The most common choices of body material are carbon steel, chrome molybdenum steel and stainless steel. Carbon steel is the most commonly used for bodies. It handles most non corrosive liquids and gases up to 800oF for continuous service or to 1000oF for occasional service. Carbon steel can be used for most condensate and steam services. Chrome – moly steel is used for higher temperatures and pressures than carbon steel, including such services as high pressure steam or flashing condensate which requires corrosion and erosion resistance. This is stronger than carbon steel and in some cases is as strong as stainless steel. It costs less than SS but not as corrosion resistance.

SS is specific for higher temperature services (1000oC and above) or in corrosive application.

Special alloys such as Super Duplex, Duplex, Hastalloy B or C, monel, nickel and titanium are also available.

The valve body can be cast, forged, wrought or fabricated. Castings are the first choices in standard sizes and ratings. Forgings are used for smaller sized bodies (generally these are high pressure ratings). Barstock are recommended when the delivery is critical and a casting or forging is not available. Fabricated type is a convenient way to manufacture large angle valves. Bonnets are manufactured from barstock of the same material as the body. Exception is the smaller low pressure chrome moly valves where SS bonnet is the standard.

Basic Parts of Control Valves

A valve is a mechanical device that controls the flow of fluid and pressure within a system or process. A valve controls system or process fluid flow and pressure by performing any of the Following functions.

  • Stopping and starting fluid flow
  • Varying (throttling) the amount of fluid flow
  • Controlling the direction of fluid flow
  • Regulating downstream system or process pressure
  • Relieving component or piping over pressure

There are many valve designs and types that satisfy one or more of the functions identified above. A multitude of valve types and designs safely accommodate a wide variety of industrial applications.

Basic Parts of Control Valves

Regardless of type, all valves have the following basic parts: the body, bonnet, trim (internal elements), actuator, and packing. The basic parts of a valve are illustrated in Figure.

Control Valves mainly have Two parts

  • Actuator Part
  • Body Part for easy understanding.

Actuator Part

For valve control, it will be classified as either a Phenumatic, Motorized and Hydrolics but is commonly used in our industry, it is Phenumatic Actuator Actuator or controlled by the wind itself. For easy maintenance Actuator simple structure which will include the Yoke, too.

Various components of the Actuator

Rain Cap 

Rain Cap I pray for them not to let water flow into the Actuator for Action of the Air to Open Actuator is that the wind will be from the bottom of the Actuator so the holes are left blank. Find something else to disabled To keep water when it rains. And must be taken off the air valve at the back.

Eye Bolt 

Eye Bolt for use on the hook. Moving the valve

Diaphragm 

Diaphragm is flexible. To change the incoming wind power and power passed to Diaphragm plate to make Actuator Stem Cell.

Spring

Spring is in the Yoke Actuator Case or, depending on the design of the manufacturer. It will act as a force for Actuator Stem Cell and a strong wind from the opposite direction to the plate Diaphragm.

Actuator Stem

Actuator Stem is interconnected with Actuator Valve Stem.

Diaphragm Case 

Diaphragm Case are the parts that are used for packing Diaphragm plate consists of two parts: the upper and lower sections.

Scale Plate 

Scale Plate is based on the position of the valve between 0-100%.

Stem Connector

Stem Connector is the link between them for Actuator Stem and Plug Stem.

Yoke

Yoke is a component that is used for connecting sections of the Actuator and Valve Body.

Body Part

Part of Body Valve is included in the Bonnet valve with which this segment is exposed to the fluid (fluid) directly, so choosing the required qualifications material (material) as well as Fluid type, Temp, Pressure and. etc

Packing Flange

Packing Flange is used for compression of the stud bolt to make the most of all the Gland Packing tight and fluid can not leak out of the neck Bonnet.

Packing Follwer

Packing Follwer is the strength of Packing Flange Gland Pakcing tightly compressed to tighten over time.

Yoke Claim Nut
Gland Packing

Gland Packing is important that we prevent the leakage of fluid up to the neck and is in direct contact with Bonnet Plug Stem The choice of material and type to fit so there is a huge need.Most of the material used is PTFE or Graphite and maintenance each time. The need to change the Gland Packing all times.

Valve Stem

Valve Stem is the strength of the Actuator and connected to Plug.

Bonnet 

Bonnet was primarily used for supporting the position of the Plug-time scroll up, scroll down to find it. No left and right But some manufacturers cut output to reduce the Bonnet Cost for the production and sale of the valve. The maintenance is also difficult. It is not to come and support the position of the Plug and Seat to meet constantly Lapping.

Stud Bolt and Nut
Gasket

Gasket is a device used to prevent leaks during the assembly of iron and steel as well as between the Body and Bonnet.

Guide Ring

Guide Ring is located in Bonnet order to align Plug straight up. Another reason for having Guide Ring Bonnet, instead of doing all the reason to reduce maintenance time Cost. Because this section is always exposed to Stem Plug sometimes wear if not Guide Ring may be a whole instead of only replacing Bonnet Guide Ring.

Guide Bushing

Guide Bushing is used for supporting Guid Ring again.

Valve Plug

Valve Plug is essential to use the force of fluid flow. And determine the flow properties as Linear, Equal Percentage or Quick Openning.

Seat Ring

Seat Ring is a component that is part of Valve Body and given the size of the Rated Cv of the valve and which supports Plug and Plug and Seat Ring must be close together. To be able to follow the Class Leakage as needed.

Valve Body

Valve Body , a major component of the round and get direct contact with the fluid. The connection to the pipeline Therefore, the size and material must be chosen accordingly. Read more at PT Rating by Valve Body structure is a frequently encountered

  • Single-Ported is a 1 plug with 1 seat
  • Double-Ported is a 2 plug with 2 Port
  • Two-Way Valve is. There will be two connections (one inbound and one outbound)
  • Three-Way Valve is to have three connections (one or two inbound and two outbound, inbound and one outbound).

Trim Set

Trim Set the control valve (Trim Control Valve) is the word of Plug Stem Seat Ring, which collectively set trim (trim set) itself.

Positioner or position

Positioner or position will be the key to control of the control valve. The industry standard device that converts the signal (signal standard), such as 4-20 mA, 3-15 psi as wind power to propel Actuator head movements.

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