Gate Valves


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Gate Valves: Purpose & Functionality

Gate valves are useful for fully open and fully closed service functions. Ideal for installation in pipelines as isolation components, the valve opens when lifting a gate out of the pathway of the fluid, and closes when the gate returns to its position. They are not an appropriate component for controlling or regulating flow in valves. Compact in design, gate valves require little space along the pipe axis and don’t restrict the flow when the gate in opened fully. They are known as a multiturn valve and operate by doing an either clockwise to close or clockwise to open rotating motion of the threaded stem. 

BENEFITS:

  • Compact design
  • Lower cost point than ball valves
  • Available in many sizes, materials, temperature and pressure ratings, and gate and bonnet designs
  • Little resistance to flow

Gate Valve Applications

Suitable for above-ground and underground installation, gate valves are useful in a wide variety of applications. It's vital to choose the correct valve dependent on its application, so there are no high replacement costs. Gate valves are often used when minimum pressure loss and a free bore is needed. 

They’re suitable for the following disciplines:

  • Agricultural
  • General industrial
  • Steam
  • HVAC
  • Boilerhouse
  • Water treatment and distribution (WRAS)
  • Compressed air and oil
  • Marine 

Types of Gate Valves

Gate valves have different kinds of characteristics that are useful for various applications, but the two main types are parallel and wedge-shaped.

Parallel Gate Valves

Compact in its structure, with reliable closing and sealing performance, a parallel gate valve uses a flat gate between two parallel seats. Mainly used in the chemical, petroleum and natural gas field, it’s the ideal valve to provide isolation when closed. 

Wedge-shaped Gate Valves

Wedge-shaped gate valves feature a disc that is in the shape of a wedge that seats between two inclined seats. Used in high flow or aggressive applications, it minimizes the vibration and chatter of the valve. 

Rising Stem & Non-rising Stem Gate Valves

Made from a range of materials, their characterization can be seen by their rising or non-rising stem. A rising stem gate valve is only useful for above-ground installation. The stem fixes to the gate, and as it rises and lowers during operation, it indicates the valve position and the possibility to grease the stem. Suitable for both above-ground and underground installations, non-rising stems are embedded onto the gate, rotating with the wedge rising and lowering inside the valve. It’s ideal for a valve with limited space as they are more compact in design.

Types of Gate Valve Material:

Gate valves come in a variety of different materials depending on the environment and application used. You can choose from the following materials:

  • Brass
  • Bronze
  • Cast Iron
  • Ductile iron
  • Stainless steel
  • Duplex
  • Carbon steel
  • Exotic alloys

FAQS:

What are gate valves used for?

Generally, gate valves are used to completely shut off fluid flow or provide full flow in a pipeline. They are installed in pipelines as isolation valves and perform by moving clockwise to close or clockwise to open along the stem. They function in the fully closed or fully open positions and consist of a valve body, seat and disc, a spindle, gland, and a wheel for operating the valve.

How many types of gate valves are there?

There are three ways to classify a gate valve, by the type of disk, body bonnet joint and stem movement. 

Types of disk include:

  • Solid taper wedge
  • Flexible wedge
  • Split wedge or Parallel disks Valve

Types of Body Bonnet Joint include:

  • Screwed Bonnet
  • Bolted-Bonnet
  • Welded-Bonnet
  • Pressure-Seal Bonnet

Types of Stem movement include:

  • Rising Stem
  • Non-rising Stem

What is the difference between a ball valve and a gate valve?

They both essentially serve the same function, however, the main difference is in the operation. While gate valves open by lifting a round or rectangular gate out of the path of the fluid, ball valves have a stem and a ball that turn horizontally. 

Why do gate valves fail?

Wear and corrosion are the most common cause of a faulty gate valve. They can wear out over time, with corrosion causing the disc to stick in either the open or closed position. If the handle is forced, it usually leads to the stem breaking and making the valve useless.