What Is A Plug Valve, And What Is It Used For? Complete Guide

What-is-a-plug-valve-and-what-is-it-used-for

Plug valves are quite commonly used in many industries because of their excellent features, and they allow a perfect flow of fluid or gas through them the way desired.

Industries like food and beverages, pharmaceuticals, oil and gas, chemical, and many more are dependent on plug valves.

However, if you want to know more about the plug valves, you must read the article below; in this guide, we have highlighted every detail about these valves and their different types.

So, let’s walk through this article below and you will learn everything about plug valves.

Overview of Plug Valves

The most important thing at first is to know what a plug valve is, how they work, and the pros of using these valves; this will make it easier for you to decide on their purchase.

Definition of Plug Valves

A plug valve comprises a manual working mechanism and offers a quarter-turn rotary movement allowing the flow to move in a straight direction.

This valve has a cylindrical plug-shaped disc and is the essential part of the valve body, allowing the fluid to pass through without turbulence.

The plug valve is suitable for use in every direction, either fully open or fully closed, supporting controlled regulation.

How Plug Valves Work

A plug valve has a hollow passage in the body, and the motion in the quarter turn allows the creation of alignment between pipe and hole, which leads to opening the valve.

When the valve is again turned to 90 degrees angle, it aligns with the pipe and makes it stand closed.

The main components of the plug valve involve the valve body, valve disc, and stem, it has a parallel seating as well, and when it is rotated, the plug fits into this seating.

The hollow shape cylinder in this valve allows the regulation of flow, and when the flow and cavity of the valve are parallel, the valve is open, and when these are perpendicular, the valve is closed.

A plug valve consists of various kinds of ports like multi-ports, standard openings, round openings, rectangular openings, and diamond openings.

In the case of multi-port, multiple pipes can be attached to allow any material to flow through the valve.

Characteristics and Advantages of Plug Valves

Plug valves have various characteristics that prove to be quite advantageous; some of these advantages offered by these valves are provided below:

  • The plug valves are very straightforward; they have lesser components and are very easy to operate.
  • They are suitable where immediate opening and shut are needed for liquid flow.
  • Plug valves have one pattern consisting of a multi-port design that allows for multiple flows; hence changing the flow direction becomes easier.
  • The plug valves can be shut off very tightly and don’t cause any leakage.
  • Plug valves are very easy to maintain and clean.
  • They allow almost all materials to pass through, including gas, liquid, slurries, and even fluids with particles.
  • Plug valves support all kinds of applications and comprise many types.
  • These valves allow for throttling and are suitable for multiple flow directions.
  • Plug valves are manufactured in different materials like metals and plastics; these valves can be used in plastic materials for corrosive flows.
  • In the case of sticky components, plug valves can be manufactured in special and customizable designs.
  • There are multiple sizes to choose from, and these could be selected according to the diameter of the pipe.

Types of Plug Valves

There are many types of plug valves, and the most common types of plug valves are discussed below:

Lubricated Plug Valves

As the name suggests, a lubricated plug valve comprises a lubricant inside, allowing the valve’s function to ease a little.

● Construction

The lubricated plug valve has a cavity and contains a sealant; there is an injection at the top where the sealant is introduced into the cavity.

This sealant protects the valve from corrosion and also eases the task of opening and closing the valve.

● Working

The lubricated plug valve moves the same way as other plug valves do; when the flow and hole of the plug are in line, the flow moves, and when it is rotated to 90 degrees, the flow stops.

However, it contains a lubricant that controls the flow and makes it easier for the valve to be rotated to turn it on or off when needed.

● Application

The lubricated plug valve is suitable for liquids containing particles within the fluid and is usually used in gas pipelines and dirty upstream systems.

Non-lubricated Plug Valves

Non-lubricated plug valves, as the name suggests, are such plug valves that consist of no sealant and have other mechanisms to work efficiently.

There are three types of non-lubricated valves, and this includes the following:

  1. Lift-type Plug Valve

As the name suggests, this plug valve has a lifting mechanism that disengages the plug from the seat so the flow may pass through.

  • Elastomer Seat Plug Valve

This type of valve comprises a plug covered with an elastomer that acts as a lubricant on its own, making the plug’s working easier to let the valve function.

  • Fully Lined Plug Valve

This non-lubricated plug valve has a Teflon-coated plug and body that allows for self-lubrication and makes the valve opening easier.

● Construction

The non-lubricated plug valves have different materials used in making the cavity that act as a lubricant and allows easy rotation and opening and closing of the valve through the plug.

● Working

The working mechanism of a non-lubricated valve involves rotating the valve handle, and the plug’s hole is in line with the fluid or gas flow.

To shut the valve off, the handle must be rotated back so that the plug becomes perpendicular to the valve seat and shuts off.

● Application

Non-lubricated valves are used where minimum maintenance is needed, and materials like fluoride, sulfur, and hydrogen must be passed.

Eccentric Plug Valve

The eccentric plug valve is used in isolated applications and comprises the mechanisms of half-plug closure.

● Construction

The eccentric plug valve has a body made using cast iron and a removable bolted cover; the plug is coated to act as a sealing, and there is a welded nickel seat on the body.

The valve shaft rotates in the bearings in the button of the valve’s body, allowing the flow to pass or stop.

● Working

In an eccentric plug valve, to open or close the valve, the plug rotates; this plug makes the eccentric seat raise a little.

The eccentric seat is raised when the plug is rotated in the open position and moves down when it is rotated in the closed position.

● Application

Eccentric plug valves are suitable for isolating applications like sewage lines, separating clean and dirty water, slurries, etc.

Expanding Plug Valve

Expanding plug valves are suitable for use where contamination needs to be avoided; hence, they do not offer an isolation mechanism.

● Construction

These valves consist of a double shut-off for upstream and downstream applications and are also frictionless.

The components of this plug valve consist of a stem, seat, bonnet, valve body, and a handle on the other side, allowing the valve to be opened or shut.

● Working

The expanding plug valve has a rotary mechanism that seals the flow path upon rotation, and there is no contact between the seat and the body.

This working mechanism of this valve prevents any contamination in the material flowing through the valve.

● Applications

The expanding plug valve is used in measuring stations, water storage tanks, and multiproduct distributors.

They are suitable in applications where contamination needs to be avoided. However, they do not provide for double isolation.

Soft-Sealed, Fire-safe Plug Valve:

Highly toxic environments may require soft-sealed plug valves as they can resist such an environment.

● Construction

The soft-sealed valve is a fire-safe valve that comprises the same parts as the standard plug valves have, but it contains a fire-proof soft seal that is Teflon made and elastic.

This elastic material is a ring between the body cavity and the valve seat.

● Working

This plug valve works when the handle is rotated, and the cavity and flow become parallel; the material passes through it, whereas when the cavity is perpendicular to the valve body, the water flow stops.

● Applications

A soft seal plug valve is used where high temperatures and corrosive materials pass through the pipelines.

The common applications of these valves consist of boiling systems, fuel control of gas and fluid, steam with low pressure, etc.

Selection Criteria for Plug Valves

Plug valves are quite convenient and very much suitable for various industrial applications, but some factors must be taken into consideration when choosing a plug valve, and this comprises of the following:

Flow Rate

When gasses and liquids pass through the valves, every kind of material has a different flow rate, some have a very fast rate, and some have a slow rate depending upon the nature of the material.

For instance, in the case of slurry, they are thick and hence have high viscosity; therefore, they flow very slowly, similar to the case of oil.

On the other hand, gas and less viscous liquids flow very fast; therefore, it is important to see how the material flows through the valve when choosing it.

Some valves are suitable for viscous materials, and some aren’t, so flow assessment is critical.

Pressure and Temperature Requirements

Some plug valves are perfect to go with a highly corrosive and abrasive environment like the soft seal valves, and some might not be suitable because of their nature of making.

So, the temperature and pressure the valve must face must be assessed beforehand so that the valve can be chosen accordingly.

If the wrong valve is chosen, it won’t fulfill the installation purpose and might be damaged.

Materials of Construction

The two common materials used in the construction of plug valves are metal and plastics; when it comes to these materials, metals are suitable for environments where abrasive materials pass through pipelines.

However, plastics are suitable for environments that are not very abrasive but may be outdoors, and protection against corrosion and rusting is needed.

Hence, where the valves are to be installed must be assessed when choosing them so that the relevant material of the valve can opt.

Valve Type Compatibility with Process Requirements

Every industrial application has a different type of material passed through the valve. Some industries require valves that offer immediate opening and closing, whereas some don’t.

Hence, it is imperative to ensure that the type of valve chosen offers compatibility with the process and application so that it proves to be the right selection.

In cases where bubble-tight plug valves are needed, the ones with the regulatory movements might not be the suitable valves to choose from.

Automation and Control Requirements

How much control you will have over the valve or if you need it over is a matter that requires attention.

You can choose between the automated, semi-automated, and manual valves; however, this decision depends on the industry they are installed.

Maintenance and Repair Considerations

Plug valves are usually very easy to use and maintain, but they have various types too, and lubricated valves need more maintenance.

So, when choosing a plug valve, it must be assessed whether this maintenance level will be possible because if not maintained properly, these valves might end up working and get jammed.

How To Choose the Right Plug Valve for Your Industrial Process?

The proper plug valve selection plays a critical role in allowing the flow of material to pass efficiently.

The material of the valve, the size and diameter of the pipe, everything must align, and the function needed to serve the purpose of application must match with the valve.

Industrial applications are critical, and one wrong selection could disrupt the entire process of production.

Therefore it is essential to choose a suitable valve that is not only made out of premium quality materials but is also capable of serving the purpose of the installation.

Conclusion

At INOXCN, you get a wide variety of plug valves for your industrial applications, and these valves are of prime quality and reasonable price.

We always offer customization and diversified options to our clients, keeping their budgets in mind, so get in touch with us today and discuss the valve details, and we will guide you.

You will always feel great dealing with us; our efficient team and highly trained engineers have been designing and manufacturing these valves for years and have a very long-term experience.

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