Door Valve:


How Do Gate Valves Work?

A linear motion valve used to start or stop fluid flow is called a gate valve. The name "gate" comes from how the disc appears in the flow stream.


Gate valve diagram:


When a gate valve is fully open, the disc is entirely withdrawn from the flow stream. When the valve is fully closed, a disk-to-seal ring contact surface is present on all sides. If a disc and seal ring are properly mated, very little or no leakage occurs across the disc when the gate valve is closed.

A gate valve can be utilised with a wide range of fluids and, when closed, offers a tight seal.


Significant drawbacks of a gate valve

  • Applications involving throttling are not appropriate.
  • In the partially open state, it is susceptible to vibration.
  • Compared to a globe valve, it is more susceptible to seat and disc wear.
  • Repairs, such as lapping and grinding, are often more difficult to do.

Disk Gate Valve Design


A number of discs are offered for gate valves. The type of disc utilised is typically used to classify gate valves:

  • strong wedge
  • supple wedge
  • broken wedge

concurrent disc

In valves with inclined seats, solid wedges, flexible wedges, and split wedges are employed. A gate valve can be used for a wide range of fluids and offers a tight seal when closed. Parallel discs are utilised in valves with parallel seats.

Gate valve

No matter what kind of wedge or disc is employed, the disc is often replaceable. These components should have a high surface hardness and replacement seats as well as discs for applications where solids or high velocity may cause rapid erosion of the seat or disc. If the seats cannot be replaced, seat damage necessitates either removing the valve from the line for seat refacing or refacing the seat while it is still in place. Replaceable seats should often be specified for valves used in corrosive service.


Design of a gate valve stem

  • Gate valves can either have a rising stem or a non-rising stem. The stem is threaded into the gate on the bottom end for non-rising stem gate valves. The gate moves up or down the stem on the threads as the hand wheel on the stem is turned, but the stem remains motionless vertically. To show valve position, this kind of valve almost invariably has a pointer-style indicator threaded onto the top of the stem.



  • The non-rising stem arrangement isolates the stem threads from the environment by keeping them inside the perimeter created by the valve packing.With this setup, there is little chance that the stem will accidentally drag dirt from the outside of the packing into the interior.



  • When the valve is opened, rising stem gate valves are made to elevate the stem out of the flow stream. There are two primary designs for rising stem gate valves. While the stem of some valves rises through the hand wheel, the stem of other valves is threaded to the bonnet.




Design of a gate valve seat




  • Gate valve seats are either built into the valve body itself or in the form of a seat ring. The seats in seat ring construction can be threaded into place or pressed into place and seal welded to the valve body.For applications that require greater temperatures, the latter type of construction is advised.


  • While pressed-in or threaded-in seats allow for variation, integral seats offer a seat made of the same material as the valve body. For the application that calls for them, rings with hard facings may be provided.


  • Small, forged steel gate valves with hard facing seats that are pressed into the body are available in some series and are rated for 2500 psig steam service in diameters ranging from 1/2 to 2 inches. Large gate valves frequently have solid wedge discs with seat rings that are threaded, welded, or pushed in. Since they may be taken out and changed, seat rings that are screwed in are regarded as replaceable.



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