Gate Valve Type, Advantage and Disadvantage, Applications

06 Aug.,2024

 

Gate Valve Type, Advantage and Disadvantage, Applications

Gate Valve Type, Advantage and Disadvantage, Applications

Gate valves are widely used for all types of applications and are suitable for both above-ground and underground installation. Not least for underground installations, it is paramount to choose the right type of valve to avoid high replacement costs.

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Gate valves are designed for fully open or fully closed service. They are installed in pipelines as isolating valves, and should not be used as a control or regulating valves.

Operation of a gate valve is performed doing an either clockwise to close (CTC) or clockwise to open (CTO) rotating motion of the stem. When operating the valve stem, the gate moves up- or downwards on the threaded part of the stem.

History of a gate valve

The term Gate Valve originated from the words gatan, gap, gasse and gat, and implies a passage with a barrier, which can be hinged on one side, allowing it to be OPENED and CLOSED.

Some of the first known gate valves were used by the Egyptians, Greeks, and Romans when irrigating fields with water. These were simple wooden barriers, but they were well-suited for the requirements of the task.

In the 19th century, intensive development of gate valves moved quickly forward due to their increasing use in industrial operations. Over time the materials involved in their manufacture were improved and modified to suit different applications.

In addition, there were significant improvements in the efficiency of both internal and external sealing methods.

 

Type of Gate Valve

There is a different type of gate valve, such as:

Standard

Wedge Types

Solid Tapered Wedge

Solid Pliable Wedge

Double Disc type

Bellow Design

Cryogenic Design

Knife Plate

Hulk Plate

The closing feature is very good.

These valves can be used both ways in the circuit

They provide laminar flow, the pressure loss is minimum

Disadvantages of Gate Valves

They cannot be opened and closed quickly.  To fully open or closed wheel or gearbox actuators, the shaft should be rotated as many as the full open revolution number.  The full open revolution number is equal to the pitch

Assembly, start-up, and maintenance require large space.

In the fully closed position, the slow movement of the slide causes high flow speed.  Due to vibration and collision, abrasion and deformation occur in the seating surfaces and the surface gets damaged from friction.

In systems where high-temperature changes irregularly, due to the load in the pipe at the valve end, leakages in gate valves occur.

At the place of operation, repair and maintenance of seating surfaces are difficult.

Application of Gate valve

Socket or butt-welding end-gate valves in air, fuel gas, feedwater, steam, lube oil, and other systems are typical applications. Threaded-end gate valves may be used in air, gaseous, or liquid systems.

Concern for leakage from threaded connection can be addressed by seal welding the threaded connection or by using thread sealants, as appropriate. In low-pressure and low-temperature systems such as fire protection systems&#; water piping or water distribution pipelines, flanged gate valves are commonly used.

Refrences:

https://www.avkvalves.eu

http://www.schuf.de

http://www.pipingguide.net

https://www.ksb.com

 

A Gate Valve and Its Advantages

A gate valve is a wedge disc for opening and closing. The movement direction of the brake is required to be perpendicular to the direction of the fluid. It can be opened and closed completely, and cannot be adjusted or throttled. The gate valve is sealed by the contact between the valve seat and the gate. Usually, the metal material is sealed and welded to improve the wear resistance. The gate is divided into rigid and elastic gates and is widely used in chemical, petroleum, light industry, hospitals, environmental protection, etc.

 

&#;. How does a gate valve work

 

How does a gate valve work? The opening and closing disc of the gate valve is the wedge disc, which has two sealing surfaces. The most commonly used mode is that the two sealing surfaces of the gate valve form a wedge. The wedge angle depends on the valve parameters, which is usually 5°, and is 2°52' when the medium temperature is not high. The gate of the wedge gate valve can form a whole, which is called a rigid gate. It is possible to manufacture gates that can produce slight deformation so as to improve the manufacturability, and compensate for the deviation of the sealing surface angle during processing. This kind of gate is called an elastic gate. After the gate valve is closed, the sealing surface can only be sealed by the pressure of the medium. In other words, according to the media pressure, the sealing surface of the gate can be pushed into the other side to ensure the sealing of the sealing surface, which is called self-sealing. Most gate valves adopt the method of forced sealing.

 

&#;. Advantages of gate valves

 

1. The flow resistance is small. The media channel inside the valve is straight, and the flow resistance is small.

 

2. It is easier for it to do the opening action. Because compared with the shut-off valve, the movement direction of the gate valve is perpendicular to the direction of the medium flow, whether it is open or closed.

 

3. High and long opening and closing time. The opening and closing stroke of the gate is relatively large, and the elevator is carried out by screws.

 

4. Water hammer is not easy to occur.

 

5. The two sides of the channel are symmetrical, and the medium can flow in any direction from both sides, which is convenient for installation.

 

6. The structure length (the distance between the two connecting end faces of the system shell) is small.

 

7. The gate valve has simple body shape, short structure, good manufacturing technology and wide application range.

 

8. The gate valve boasts compact structure, good valve rigidity, soft channel, small flow resistance, long sealing surface between stainless steel and hard alloy, long service life, PTFE packing, reliable sealing, light and flexible operation.

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How to Select the Right Valve (with Pros & Cons)

The suitability of a valve for a specific application is defined by the materials used in relation to the transported fluid as well as its mechanical design. Here is Indelac Valve Selection Guide.

 

 

Valve Selection Table

The tables below can be used as a valve selection guide taking into consideration the state of material, its nature and the function of the valve.

Conveyed Fluid

Nature of Fluid

Valve Function

Type of Disc

Liquid Neutral (Water, Oil, etc) On/Off Gate Rotary ball Plug Diaphragm Butterfly Plug gate Control valve, modulating Globe Butterfly Plug gate Diaphragm Needle Corrosive (Acid, alkaline etc.) On/Off Gate Plug gate Rotary ball Plug Diaphragm Butterfly Control valve, modulating Globe Diaphragm Butterfly Plug gate Hygienic (Food, beverages, drugs etc) On/Off Butterfly Diaphragm Control valve, modulating Butterfly Diaphragm Squeeze Pinch Slurry On/Off Rotary ball Butterfly Diaphragm Plug Pinch Squeeze Control valve, modulating Butterfly Diaphragm Squeeze Pinch Gate Fibrous Suspensions On/Off, Control valve, modulating Gate Diaphragm Squeeze Pinch

 

Conveyed Fluid

Nature of Fluid

Valve Function

Type of Disc

Gas Neutral (Air, Steam etc) On/Off Gate Globe Rotary ball Plug Diaphragm Control valve, modulating Globe Needle Butterfly Diaphragm Gate Corrosive (Acid vapors, chlorine etc.) On/Off Butterfly Rotary ball Diaphragm Plug Control valve, modulating Butterfly Globe Needle Diaphragm Vacuum On/Off Gate Globe Rotary ball Butterfly

 

Conveyed Fluid

Nature of Fluid

Valve Function

Type of Disc

Solids Abrasive Powder (Silica, etc) On/Off, Control valve, modulating Pinch Squeeze Spiral sock Lubricating powder (graphite, talcum, etc) On/Off, Control valve, modulating Pinch Gate Spiral sock Squeeze

 

 

Valve Type Pros and Cons

BSTV Product Page

Because everything is easier to understand with a table, here is another one summarizing pros and cons for the most common valves.

Valve

Advantages

Disadvantages

Butterfly

Quarter turn

Difficult to clean

Open port

Difficulty with slurries

Used with chemical or corrosive media

Throttling limited to low differential pressure

Compact, lightweight design

Potential for cavitation and choke

Available in large sizes

Unguided disc movement is affected by flow turbulence

Low pressure drop and high-pressure recovery

 

High coefficient of flow

Ball

Superior ease of operation

 Poor throttling characteristics

Maintains and regulates high volume,

 Difficult to clean, leads to contamination

high pressure, and high temp flow

 

Rugged construction and long service life

Low purchase and maintenance cost

Able to function without side loads

Permits inspection and repair of seats and seals without removing the valves' body from the line

Does not require lubrication

Diaphragm

Extremely clean

Can only be used in moderate temperature (-60 to 450ºF)

Leak proof seal

Can only be used in moderate pressures (approximately 300psi)

Tight shut-off

Cannot be used in multi-turn operations

Easy maintenance

No industry standard face-to-face dimensions

Repairs can be made without  interrupting pipe line

The body must be made of corrosive resistant material

Reduce leakage to the environment

 

Gate

Available in large sizes

Low pressure limitations

Can be used with slurries and viscous liquids

Slow open and close time

Used as a shut off valve

Erosion of the seat and disk can occur

Easy to maintain and disassemble

Poor throttling characteristics

Inexpensive

Difficult to repair

Inherently fire-safe (when used with a metal sheet)

Should not be used in sanitary applications

Bidirectional

 

Globe

Can be fast-acting

High head loss

Precise control

Large opening for disk assembly

Can be used in high-pressure systems

Heavier than other valves

 

Cantilevered mounting of the disk to the stem

Low coefficient of flow

Not good for clean or sterile applications

Pinch

Very Clean

Cannot be used in high temperature applications

Excellent drainage

Cannot be used in high pressure applications

Minimal turbulence

Cannot be used with gas media

Low airborne contaminants

 

Low maintenance

Low weight

Can be used in explosion-proof lines

Inexpensive

Once the right valve has been selected, it is time to select the right actuator! See link below to Indelac Actuator Selection Guide: