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Your Position: Home - Hardware - The strongest introduction about gate valves

The strongest introduction about gate valves

Author: Clarissa

Jul. 06, 2021


Gate Valve Working Principle

Gate valves are mainly include slab gate valve, wedge gate valve and so on that consist of three major components: body, bonnet, and trim. The body is generally connected to the piping by means of flanged, screwed, or welded connections. The bonnet, containing the moving parts, is joined to the body, generally with bolts, to permit cleaning and maintenance. The valve trim consists of the stem, the gate, the wedge, or disc, and the seat rings. The main operation mechanism is very simple. When the hand-wheel is turned, it rotates the stem, which is translated into the vertical movement of a gate via threads. They are considered multi-turn valves as it takes more than one 360 ° turn to fully open/close the valve. When the gate is lifted from the path of the flow, the valve opens and when it returns to its closed position, it seals the bore resulting in a full closure of the valve. 

gate valve design parts.jpg

Different Gate Valve Design

  • Wedge Gate Valve

Wedge gate valves differ from slab gate valves in that the closure member is wedge-shaped instead of slab. The purpose of the wedge shape is to introduce a high supplementary seating load that enables wedge gate valves to seal not only against high, but also low, fluid pressures. The degree of seat tightness that can be achieved with wedge gate valves is therefore potentially higher than with conventional slab gate valves. Efforts to improve the performance of wedge gate valves led to the development of a variety of wedge designs; the most common ones are described in the following section. 


  • Slab Gate Valve

Slab gate valves have a slab faced gate like closing member. This closing member may consists of a single disc or twin discs with a spreading mechanism in between. The force that presses the disc against the seat is controlled by the fluid pressure acting on either a floating disc or a floating seat. Because the disc slides across the seat face, slab gate valves are also capable of handling fluids, which carry solids in suspension. 

  • Rising Stem Gate Valve

Rising stems are fixed to the gate and they rise and lower together as the valve is operated, providing a visual indication of the valve position and making it possible to grease the stem. A nut rotates around the threaded stem and moves it. This type of valve has an inside screwed stem and the packing is subjected to wear because of the up and down movement and turning motion of the stem. This type is only suitable for above-ground installation.

  • Non Rising Stem Gate Valve

Non-rising stems are threaded into the gate, and rotate with the wedge rising and lowering inside the valve. Rotation of the wheel operates the valve, but the stem does not come out of the housing. They take up less vertical space since the stem is kept within the valve body. Non-rising valves are almost always fitted with a local visual pointer which indicates the position of the valve. Gate valves with non-rising stems are suitable for both above-ground and underground installations. 

  • Resilient seated gate valve

Resilient seated gate valves have a common valve bottom that allows sand and pebbles to pass freely through the valve. If impurities pass through when the valve is closed, the rubber surface will close around the impurities when the valve is closed. When the valve is closed, the high quality rubber compound will absorb the impurities, and when the valve is opened again, the impurities will be washed away. The rubber surface will return to its original shape to ensure sealing. This is where the resilient seated gate valve differs from the metal seated gate valve, which will lose its fastening ability much faster because on how thoroughly the pipe is flushed during installation or maintenance, sand and pebbles will be embedded in the bore and the conical wedge coincides with the depression in the bottom of the valve and eventually any metal wedge will eventually lose its fastening ability.


Gate valves meet the majority of valve requirements in process piping and are considered one of the most used valves of all the valves employed in refineries, petrochemical, and gas processing plants where pressure remains relatively low, but temperature may be very high. They are suitable for most fluids including steam, water, oil, air, and gas. Gate valves of any type can not be used for regulation or throttling because the flow rate of the fluid is not proportional to the opening of the valve and therefore the flow of the fluid can not be precisely controlled. In order to be able to use the gate valve for a long time to reduce replacement costs, the shear force of high velocity flow d should be reduced, which can cause the gate valve to open partially due to vibration, which can damage the seat surface and prevent a tight seal. Maintenance and replacement of gate valves should be inspected regularly. 






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