Valve

The valve, abbreviated as V, is a mechanism used to stop or open and regulate flow.  The type of valve used depends on the application.  In general, there are valves used for on-off (open-closed) applications, and throttling valves which can adjust flow.  All valves fall into two basic types: stop valves and check valves.

  • Stop Valves  -  Stop valves are used to shut off or partially shut off the flow of liquids.  Stop valves are divided into four basic types of valves: gate, globe, ball and butterfly.
  • Check Valves  -  Check valves are used to allow the flow of fluids in only one direction.  There are four basic types: diaphragm check, lift check, swing check, and tilting-disk check.
  • Valve Turns
    • Multi-turn Valves or Linear Motion Valves: Gate Valve, Globe Valve, Pinch Valve, Diaphragm Valve, Needle Valve
    • Quarter Turn Valve or Rotary Valve: Plug Valve, Ball Valve, Butterfly Valve
    • Self-activated Valves: Check Valve, Pressure Relief Valve

 

valve types

Ball Valve

  • Full Port Ball Valve, Reduced Port Ball Valve, Standard Port Ball Valve, Three-way Port Ball Valve, Trunnion Ball Valve

Butterfly Valve

  • Flange Style Butterfly Valve, Lug Style Butterfly Valve, Wafer Style Butterfly Valve

Check Valve

Control Valve

  • Back Pressure Valve, Choke Valve, Flow Control Valve, Level Control Valve, Pressure Control Valve, Temperature Control Valve

Diaphragm Valve

Gate Valve

  • Flap Gate Valve, Knife Gate Valve, Slide Gate Valve, Wedge Gate Valve

Globe Valve

  • Angle Globe Valve, Cross Globe Valve, Straight Globe Valve

Needle Valve

Pig Valve

Pinch Valve

Plug Valve

  • Conical Plug Valve, Cylindrical Plug Valve, Lift Plug Valve, Multi Port Plug Valve

Pressure Relief Valve

Specialty Valve

 

Valve Terms

  • Actuator  -  A device that moves the stem by electric, hydraulic or pneumatic to a open or close position.
  • Actuator stem  -  A part used to connect the valve plug with the piston actuator.
  • Adjusting screw  -  A part used to compress the actuator spring.
  • Angle valve  -  A body configuration with one port perpendicular to the other port.
  • Automatic control valve  -  Final control element used in process systems to regulate flow.
  • Ball  -  The closing element of a ball valve.
  • Ball check valve  -   A check valve that is much like a swing check valve but instead of having a gate or guided disk, uses a ball to control flow.
  • Ball valve  -  A quarter turn valve used for changing the direction of a process stream (divert or shut off).
  • Barstock valve -  Barstock valve has a body machined from a solid metal.
  • Bellows sealed valve -  A bellows is a sealing device which prevents line leaking between the stem and the body of a valve. It is a flexible metal, usually made of stainless steel used to seal the stem through the shafts.
  • Body -  The main casing container used for the flow of fluids and to hold the moving parts and seals of the valve.
  • Body rating (actual)  -  The interaction between being safe, acceptable flowing fluid pressure and temperature and the body, excluding all internals.
  • Body rating (normal)  -  The theoretical pressure rating of the body excluding all internals. 
  • Bolted bonnet  -  A bonnet that is connected to the body with bolts.
  • Bonnet  -  The top part of a valve that is attached to the body that contains guids, packing, and stem.
  • Bonnet bolts  -  Bolts that hold the bonnet to the body.
  • Bottom flange  -  A flange at the bottom of a valve or opposite the bonnet.
  • Butterfly valve  -  A quarter turn valve (90° or less) with a circular disk as its closing element. 
  • Check valve  -  These valves are designed to allow the process fluid to flow in only one direction to prevent backflow.
  • Choke Valve  -  Valves used in severe service valves designed for oil and gas applications.  They are used for controlling the flow rates or pressure on production, steam or water injection.
  • Cold box bonnet  -  A hollow extended bonnet which allows stagnated, moderate temperature gas to form, protecting the packing from cryogenic temperatures.
  • Clapper  -  The hinged closure of a check valve.
  • Close-off rating  -  The maximum pressure drop at which a valve can take without leaking when completely closed.
  • Closing pressure  -  The pressure at which a valve closes or reseats.
  • Control valve  -  This valve controls the flow capability by changing the flow passage size as directed by a signal from a controler.
  • Design pressure  -  The maximum pressure at which a valve can operate.
  • Direct pressure  -  Pressure applied by the flow against the back of the closure and/or opposite the seat end of the valve.
  • Disk  -  A valve assembly part that comes in contact with the seat to close off the flow.
  • Disk stroke  -  When the valve stem moves from a closed to open position.
  • Double-acting  -  Term used to describe supplying and exhausting air to both sides of the pistonsimultaneously.
  • Double block and bleed  -  When under pressure the valve has the capability to maintain a seal across both the upstream and downstream seat rings and have the body cavity bleed down to atmospheric pressure.
  • Double top-guided  -  A packing box configuration which uses two widely spaced guides, one at each end of the packing box, to guide the plug.
  • Drain plug  - A plug at the bottom of a valve, when removed it drains and flushes the body cavity.
  • Electric actuator  - It is mounted on a valve and receive a signal that moves the closing element to the desired position.
  • Eccentric ball  -  Similar to a ball valve except it usually contains a segmented ball or half ball.
  • Eccentric plug  -  Has an vertical rectangular opening in the body of a plug valve where the closure is rotated and seated against.
  • Expanded outlet  -  A body configuration with standard trim gallery and oversized ports.
  • Extended bonnet  -  A longer than normal bonnet which protects the packing and actuator from extreme heat or cold.
  • Extension  -  Equipment used to provide operating gear accessibility to a below grade valve.
  • Face-to face  -  The distance from end to end of the valve.  These dimensions are goverened by ANSI specifications.
  • Facing  -  The contact surface finish of a flange.
  • Fail-safe  -  A system designed to open, close, or hold in last position should the air supply fail.
  • Floating ball  - A closing element of a ball valve designed not to be held rigidly on a rotational axis but floats free between the seat rings.  When under fluid pressure the ball will be pushed against the downstream seat.
  • Floating ball valve  -  Used in low pressure or small bore processes.
  • Four-way (four-port)  -  These closure elements come with two seperate passageways in L shapes.  Each passageway connects to two different lines.
  • Full port (full bore)  -  A valve port opening that is equal to the pipe size or valve opening.
  • Handlever  -  A device attached to rotary-motion valve with preset positions to manually position, open or closed, the valve.
  • Handwheel  - A wheel operator used to turn the stem and open or close the closure elements.  Handwheels can be found on ball, gate, and globe valves.
  • High performance butterfly valve  -  HPBV is not a butterfly valve but its function and dimensions are equivalent.
  • Gasket  -  A seal between two components, usually bolted.
  • Gate valve  -  One of the most frequently used valve in piping systems and is classified as either "rising-stem" or "nonrising-stem" valves.
  • Gland flange  -  A part used to retain and control the compression force on the packing on the bonnet.
  • Globe valve  -  A type of valve used for regulating fluid flow, both on/off and throttling, it is a control valve.
  • Leakage  -  The amount of fluid that will pass through a control valve when it is fully closed at a given pressure and temperature.
  • Lever  -  A device used for quarter-turn valves.
  • Lift check valve  -  A check valve that is very much like a piston check valve where the flow lifts a disk when the valve is open.
  • Limit stop  -  A device attached to the actuator used to limit or restrict the motion of the actuator.
  • Limit switch  -  A switch used to indicate a valve's open, closed, or intermediate position.
  • Lock-up system  -  A system used to hold the actuator in last operating position upon air failure.
  • Lubricator  -  A device that supplies lubricant to the packing box.
  • Lug butterfly valve  -  Connects directly to the flanges by means of a lug or machine bolt.
  • Maximum pressure  -  The maximum pressire limitations of the fluid that a valve can withstand.
  • Maximum temperature  -  The maximum temperature limitations of the fluid that a valve can withstand.
  • Mixing valve  -  Has two inlet ports and one common outlet port.
  • Multiport  -  These valves can either be three-way or four way valves.
  • Offset globe body  -  Body configuration with inlet and outlet ports parallel but offset.  They are not in-line.
  • On-off valve  -  A type of valve that only has two positions, either open or closed and can not be a throttling valve.
  • OS&Y (outside screw and yoke)  -  A valve design in which the stem threads are above the packing gland or outside the valve body and there is a yoke to support the top or outer end of the stem.
  • Packing  -  Material uesd to seal the valve from leaking around the plug stem.
  • Packing box  -  Internal bore of bonnet which contains guiding and packing.
  • Pig valve  -  An alternative to conventional pig launchers with the capable of launching and receiving.
  • Piston  -  Part used to seperate two air chambers of piston actuator.
  • Piston actuator  -  Double-acting actuator design with piston inside actuator.  
  • Plug valve  -  A quarter turn valve that has a conical or cylindrical plug that is rotated within the valve body to stop flow when needed. 
  • Poppet valve (mushroom valve)  -  An oval, round, tapered plug, or disk shaped end with a shaft, used to control the closing and opening for gas and vapor.  
  • Port  -  A passageway that allow fluid to flow through the closure element / valve.
  • Position indicator  -  Any external device which helps you get a clear visually view of whether a valve is in the closed and open position.
  • Pressure drop  -  The difference in upstream and downstream pressure.
  • Quarter turn  -  A shut-off valve that turns one-quarter on the center vertical axis to close or open the valve.
  • Quick-opening  -  A two-way valve that creates the maximum flow capacity as soon as the stem raises.
  • Reduced port (reduced bore)  -  A valve port opening that is smaller than the pipe size or valve opening.
  • Reduced port ball valve (standard or regular)  -  A reduced bore valve has a smaller bore diameter in the ball than the internal diameter of the pipe.
  • Regulating valve  -  A valve that controls the flow rate or pressure in a process.  A flow regulating valve maintains a constant flow rate where a pressure regulating valve maintains a constant downstream pressure.  A regulating valve could be a flow control valve or a pressure control valve.
  • Reverse flow  -  When the flow moves in the oposite direction of the norman system operation.
  • Reverse pressure  -  The pressure applied against the face of a valve closure.
  • Rising stem  -  A stem that rises as the valve is opened.
  • Seat  -  The inner surface of the valve body which creates a tight shut-off.
  • Seat load  -  The contact force between the seat and the valve disk.
  • Seat retainer  -  Trim component that clamps the seat ring in place.
  • Seat ring  -  Creates a tight shut-off surface inside the body for the disk.
  • Set pressure  -  The set pressure is the point where a pressure relief valve (PRV) is set to start opening. The set pressure should be equal to or less than the maximum allowable working pressure (MAWP) of the vessel or piping that it is protecting.
  • Shaft  -  Component in a rotary valve that connects the closure member to the actuator.
  • Shut-off pressure  -  The differential pressure against the closure when closed.
  • Shut-off valve  -  A block valve that only has two positions, either open or closed and can not be a throttling valve.  Sometimes used for emergeny shutdown of the system.
  • Stem (shaft)  -  A shaft that is connected to the handwheel or gear operator and then to the closing element of the valve.
  • Stem extension  -  An extension of the valve stem used to provide operating gear accessibility to a below grade valve.
  • Stem nut  -  A threaded nut that surrounds the valve stem threads and causes the stem to move when rotated.
  • Stop-check valve  -  Essentially, two valves built into one.  It can act as a globe valve to isolate or control the flow rate.  It also acts as a check valve by preventing reverse flow.
  • Stop Valve  -  Used to shut off or partially shut off the flow of liquids.
  • Stroke  -  The distance the valve piston, plug, or stem, moves from a fully closed to fully open position or vice versa.
  • Stuffing box  -  The chamber surrounding the stem where it emerges from a pressurized space used to contain the packing.
  • Swing check valve  -  It is inexpensive and simple to operate and repair.  A check valve that has a disk that pivots about a hinge pin. 
  • Three-way (three-port)  -  These closure elements come in T or L shaped passageways.  The passageway connects to two or three different lines.
  • Torque  -  The rotational force used to move a shart.
  • Transducer  -  A device used to transfer an electrical signal to a pneumatic signal.
  • Transfer case  -  Component in a ball and butterfly valve that converts linear actuator motion to rotary shaft motion. 
  • Trim  -  Valve trim is the inner components of the valve that are exposed to the process fluid.  Because they are exposed to the process, they are more likely to wear out than other components like the valve body or the bonnett.  Because of this, valve trim is usually designed to be removed and replaced when necessary.
  • Trunnion ball  -  You can tell the difference between the floating and trunnion ball valve by the fixed shaft on the bottom of the body and grease injection fitting.
  • Trunnion ball valve  -  Trunnion design is simply the use of upper and lower supports to retain the ball under pressure.
  • Two-way (two-port)  -  These closure elements come in straight through passageways.  The passageway connects to one line. 
  • V port  -  The ball closure element has a V shape opening turned on its side.  This allows the closure to be opened and closed so to control the flow much better.
  • Vena Contracta  -  The point immediately downstream from an orifice or valve seat which is the point of lowest pressure and highest velocity.
  • Volume booster  -  A device used to increase the actuator stroking speed.
  • Volume tank  -  Air tank used to supply additional air to stroke the valve upon air failure.
  • Wafer butterfly valve  -  A valve that is sandwiched between two flanges.
  • Wedge  -  The closure element of a gate valve.  A wedge is opened and closed by the stem.
  • Yoke  -  A bracket to support the top or outer end of the stem and stem bearing used in gate and globe valves.

 

Valve Standards

ASME Standards

  • ASME B16.10 - Face to Face and End to End Dimensions of Valves
  • ASME B16.34 - Valves Flanged, Threaded and Welding End

ISO Standards

  • ISO 15848-1 - Industrial valves -- Measurement, test and qualification procedures for fugitive emissions -- Part 1: Classification system and qualification procedures for type testing of valves
  • ISO 15848-2 - Industrial valves -- Measurement, test and qualification procedures for fugitive emissions -- Part 2: Production acceptance test of valves

MSS Standards

  • MSS SP-6 - Standard Finishes for Contact Faces of Pipe Flanges and Connecting-End Flanges of Valves and Fittings
  • MSS SP-25 - Standard Marking Systems for Valves, Fittings, Flanges and Unions
  • MSS SP-88 - Diaphragm Type Valves

 

Valve Datasheets

Valve TypeDatasheets
Valves All Valves, ANSI (in)
Ball Ball Valve, ANSI (in)
Butterfly Butterfly Valve, ANSI (in)
Check Check Valve, ANSI (in)
Gate Gate Valve, ANSI (in)
Globe Globe Valve, ANSI (in)
Plug Plug Valve, ANSI (in)

 

Valve Associations

 

Valve Drawings

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Valve Related Articles

Display #
Title
Actuator
Back Pressure Valve
Ball Check Valve
Ball Valve
Bibb
Bonnet
Butterfly Valve
Check Valve
Check Valve Standards
Choke Valve
Crack a Valve
Extended Bonnet
Extended Outlet
Gate Valve
General Valve Standards
Glade Flange
Globe Valve
Handwheel
Lift Check Valve
Limit Stop
Limit Switch
Lock Closed
Lock Open
Normally Closed
Normally Open

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