Introduction

If you are involved in the industrial or manufacturing sector, you may have heard of plug valves. They are commonly used to regulate the flow of fluids and gases in pipelines. Plug valves come in two variants: lubricated and non-lubricated. In this article, we will explore the differences between these two types of plug valves and help you decide which one is best suited for your specific needs.

What is a Plug Valve?

Before we dive into the differences between lubricated and non-lubricated plug valves, let's first understand what a plug valve is. A plug valve is a type of valve that uses a cylindrical or tapered plug to control the flow of fluids or gases through a pipeline. The plug can be rotated inside the valve body to open or close the valve. You can learn more about plug valves by reading our previous content: Plug Valve

Lubricated Plug Valves

Lubricated plug valves, as the name suggests, are designed to use a lubricant to ensure smooth operation of the plug inside the valve body. The lubricant is applied to the sealing surfaces of the plug and the valve body to reduce friction and wear. The lubricant also helps to seal any gaps between the plug and the valve body, preventing leakage of the fluid or gas being transported.

Advantages of Lubricated Plug Valves

High sealing performance

Lower operating torque

Longer lifespan

Reduced risk of leakage

Disadvantages of Lubricated Plug Valves

High maintenance cost

Possible contamination of the fluid or gas with the lubricant

Limited temperature range

Limited chemical compatibility

Applications of Lubricated Plug Valve

• Pressures over 2500 psi (17250 kPa)

• Air

• Gas

• Acids

• Water

• Alkalis

• Steam

• Oil and fuel

Non-Lubricated Plug Valves

Non-lubricated plug valves are designed to operate without the need for a lubricant. Instead, they use a self-lubricating material, such as Teflon, to reduce friction and wear between the plug and the valve body. Non-lubricated plug valves are often used in applications where contamination of the fluid or gas being transported is a concern.

Advantages of Non-Lubricated Plug Valves

Low maintenance cost

No risk of contamination of the fluid or gas

Wide temperature range

High chemical compatibility

Disadvantages of Non-Lubricated Plug Valves

Lower sealing performance

Higher operating torque

Shorter lifespan

Increased risk of leakage

Applications of a Non-Lubricated Plug Valve

Nearly universal: Air, gas, and vapor applications

Oil or natural gas piping

Coal slurries, mineral ores, and mud

Sewage applications

Vacuum to high-pressure

Sealant/Lubricant Requirements

When using a lubricated plug valve, it is essential to match the sealant with the medium flowing through it. Otherwise, you could contaminate the fluid. The sealant also must be able to withstand high temperatures if required by the application.

Plastic sealants are used to lubricate plug valves. A suitable sealant has the following qualities:

• Proper elasticity

• Resistance to solvents and chemicals

• Ability to form an impervious seal under pressure

• Anti-corrosive

How to Choose Between Lubricated and Non-Lubricated Plug Valves

Both lubricated and non-lubricated plug valves have their own advantages and disadvantages. The choice between the two depends on the specific needs of your application. If high sealing performance is critical, lubricated plug valves may be the best choice. However, if contamination of the fluid or gas is a concern, non-lubricated plug valves may be the better option. We hope this article has helped you understand the differences between these two types of plug valves and aided you in making an informed decision.