Lubchem Incorporated is excited to invite you to join our extended online community. This is your opportunity to connect with us as we offer you extra snippets of our knowledge, experience, and expertise in the form of daily articles, videos, and other information. Here’s a glance at what you can expect: 

Your Source for Biodegradable Lubricants

We spend most of our time taking care of our valued clients like you and don’t always have the opportunity to dig a little deeper in conversation. Our blog is that opportunity. You will find original content covering a wide range of topics and information useful and interesting for you. Our original articles will fall into one of the following categories: 

1) Valuable information and resources

We strive to provide you with information that’s useful to you about biodegradable lubricant products and equipment. Accordingly, the bulk of our content will fall into this category.  

Here we will cover a broad range of topics, giving you the benefit of our expertise and valuable experience in the chemical manufacturing industry. Articles in this category are designed to address topics you may have questions about, will find interesting, or important things you may not have yet encountered. This is your opportunity to stay informed.

2) Industry updates

Every once in a while there may be changes, advancements, or other updates specific to the broader manufacturing industry that you may want to know about. These articles will be designed to give you a breakdown of what’s happening and what it means for you. They will be low in frequency, but full of important information.

3) Company news

Sometimes we may have company changes, improvements, and enhancements that you may be interested to hear about. These blog posts are intended to make you aware of our growth and progress and how it will benefit you. They’re also intended to give you an inside look at our company values and culture. They will also be fewer in frequency but will help you stay connected.

Follow Us On Social Media

In addition to our original articles, we also share a wealth of other information and videos of interest from various sources across several social media platforms. Connect with us on Facebook, Twitter, and Linkedin to receive invaluable information and updates for you and your friends and family. Stay tuned for more exciting content from our team!

Have questions about our products and equipment? Contact us for more information about biodegradable lubricant solutions.


This year we mark the 70th anniversary of Lubchem! We are celebrating 70 years of manufacturing and delivering world-class pressure-tested lubricants, and greases especially for the oilfield industry, with 70 years of leadership and innovation.
By delivering our wide range of lubricants and greases and related products we changed the world of the oilfield industry and ensured that you never halt even for a fraction of a second.
We are excited about all that we have achieved in that time to better serve our all the valuable clients and the oilfield industry, as well as create new innovative ways to help business, making the case for robust standards across all oilfield industry outputs, and enabling the expansion of your business in America and around the world.

At Lubchem we pride ourselves on being American and all our products are proudly made in the USA. We work every day to continuously improve our world-class services and the quality of our lubricants and greases that we produce, and we are looking forward to the future and all the possibilities that bring.



We have expertise in the petrochemical and oilfield industry and that’s why after understanding the needs of the industry we have manufactured all the solutions to help.
We have expertise in petrochemical and oilfield industry products, which is why we manufacture all the solutions for resolving all the types of issues that you face while working. The wide range of our life easing solutions for the petrochemical and oilfield industry include:

-Valve lubricants
-Valve cleaners and flushes
-Lubricants for equipment and maintenance
-Wireline greases and sprays
-Pipeline cleaning fluids
-Rust and corrosion inhibitors
-Drilling fluid toll blending
-Downhole lubricants
-Private label blending

That’s not all! We got a whole range of all the products that you ever need while performing your job. Browse our official product catalog to read everything about the products that you need.


Thanks for staying with us with this whole journey of 70 continuous years of leadership and innovation. This won’t be possible without your love and supports to complete this long journey that we will keep continuing till we get support from you. Lubchem will keep delivering you everything that we promised since that first day you chose us.


Polyalphaolefin (PAO) is by far the most common major synthetic base oil used in industrial and automotive lubricants. It is a synthetic hydrocarbon (SHC) that mimics the best hydrocarbon (branched) structure found in mineral oils.


Characteristics Of Polyalphaolefin

Polyalphaolefin does not contain ring structures, double bonds, sulphur, nitrogen components, or waxy hydrocarbons. The absence of these structures and materials results in a very non-polar base oil with a high viscosity index (of approximately 130), excellent low-temperature flow and pour-point characteristics, good oxidation stability, and compatibility with mineral oils, paints, and seals commonly found in lube oil systems. Because of their controlled structure, PAOs do not contain lighter, more volatile (small) hydrocarbons. This lowers their volatility, creates less hydrocarbon tailpipe emissions, and raises the flashpoint.


PAOs are used extensively in automotive fluids as well as hydraulic, gear, and bearing oils, working in extremely cold climates or hot applications. They are also employed as base fluids in some wide temperature range greases. One application in which they have not worked well is in high-temperature (high-pressure) reciprocating air compressors where valve deposits have been an issue.


However, nothing is perfect, and polyalphaolefin base oils do have a few negative characteristics. These include the tendency to shrink seals and trouble dissolving common oil additives. Therefore, they are commonly blended or combined with organic ester synthetic base oils to provide a blended base oil that does not have these negative characteristics. Polyalphaolefins also have poor fire resistance and biodegradability.


Synthetic Hydrocarbons (SHC)


The term synthetic hydrocarbon (SHC) is a general term. Several synthetic base oil types fall into the SHC category. These include PAOs and relatively common polyisobutenes (PIB), which are sometimes used as oil additives or as base oils in two-stroke engines.

Read our blog: What are Oil Solenoid Valves?


Strengths of Polyalphaolefin

  • Low volatility
  • Compatible with mineral oils
  • High viscosity index (VI)
  • High thermal oxidative stability
  • Good flow properties at low temperatures
  • Non-toxic

Weaknesses Of Polyalphaolefin

  • Limited biodegradability
  • Limited additive solubility
  • Seal shrinkage risk

History And Facts Related To Polyalphaolefin


  • Developed in the 1930s; first commercial engine oils in 1970s
  • Made from ethylene gas; still crude oil/natural gas-dependent
  • Higher temperature resistance than mineral oil (PAO up to approximately 160°C (320°F) continuous service; 270°C (520°F) intermittent)
  • No wax content, therefore the best low temperature of all synthetics (approximately minus 50°C to minus 60°C or minus 70°F)
  • Higher VI (approximately 130 to 140) than mineral oil (nearly 100)
  • Less volatile than mineral oil (higher flash point, less flammable, lower hydrocarbon emissions)
    • Lower natural lubricity than mineral oil (Polyalphaolefin base oil not necessarily less wear than mineral base oi)
  • Compatible with mineral oil
  • Problems – very non-polar (low natural solvency, additive solubility, lower lubricity, and film strength)
  • Forms hard deposits in reciprocating compressors
  • Must blend in 5 to 20 percent ester base oil for seal swell, additive solubility, and lubricity
  • Not biodegradable
  • Costs four times more than mineral oil, less than other synthetics

Buy It From LubChem


You can buy these and related types of products from LubChem. We provide all types of Lubricants and Greases that you might require for your industry. You can contact our distributors. To locate LubChem product distributors just visit our site or call us. Do it now to find the best lubrication solution for you.

The Lubchem Engine Oil Drain’s spring-assisted ball valve replaces your standard issue oil drain plug and makes oil changes easier, cleaner, and less time-consuming. The consumer will be able to clearly feel the difference in the performance while using the Lubchem’s Engine Oil Drain Valves as compared to its old standard Engine Drain Valves. These are the easiness consumers can expect from us after using our products:

  • One-Touch Operation saving your valuable time
  • Allows for clean and mess-free oil changes so ease up the oil change process
  • Safely change your oil without contacting hot oil for extra protection
  • Eliminates stripped threads and frozen plugs
  • Simple to install and operate for saving time
  • Reduces time to complete an oil changing process
  • Ideal for sampling analysis as a small amount of oil can be drawn without shutting off the engine

Installation and Operation

Visit our website or contact us by calling us at our always available [(800)%20929-0244]toll free number to know more in detail about the installation and operation process for all Lubchem Engine Oil Drain Valves. We always love to answer your queries and resolve them. Just contact us and feel the experience.


  1. Always drive carefully, and if you run over any foreign object on the road pull over and check the valve for any damage or leak for increasing its life.
  2. N-Series valve (with nipple to accept hose) is not recommended for passenger cars with low clearance.

Lifetime Limited Warranty

We offer a LIFETIME LIMITED WARRANTY on all our manufactured products, in case of faulty workmanship and/or material to the original purchaser (with proof of purchase). For any defective product, Lubchem will replace the product at no extra charge. This warranty does not cover any damages due to misuse, abuse, negligence, or accident. This warranty is valid only in the United States and Canada.

Know more about our other products

To know more about other products please visit our website and explore it to get familiar with all the products and services that Lubchem provides.

For many years, electrically powered solenoid valves have been employed in the oil heat business. They have a beneficial purpose and give several advantages.

Benefits of Using a Solenoid Valve

At shutdown, the quick-acting solenoid almost eliminates smoke. The burner airflow and static pressure are still sufficient to complete combustion of any leftover oil vapors in the combustion region before the engine coasts to a stop by promptly ceasing the oil supply to the nozzle. This quick shutoff has been proved in tests to remove smoke during shutdown and lead to less heat exchanger fouling.


In addition, the solenoid offers a secondary cut-off that works in tandem with the pump cut-off. With gravity-fed oil supply systems or setups where the storage tank is positioned above the burner, this is advantageous. In the event that the pump cut-off fails, the solenoid acts as a backup until the next repair call.


The solenoid valve offers an electrically controlled, immediate cut-off. This is especially useful if specific programs cause rumbles or pulsations when shutting down. The somewhat slower hydraulic pump cut-off, which is based on the engine coast-down rpm, is preferable.


The burner may be utilized with either pre-purge or post-purge control systems with the help of a solenoid valve. Until the purge phase is through, it prevents oil from flowing to the nozzle. A valve-on delay feature is possible with a delayed solenoid valve. Temperature is, nevertheless, a factor. Its delay is reduced by heat from the environment or fast cycling, but it is enhanced by cold. As a result, it’s a one-size-fits-all solution.


Construction of a Solenoid Valve

When the coil is de-energized, the conventional solenoid valve used on home burners closes. The device might be built for either direct action or delayed opening. Solenoid valves can be categorized as non-delayed or delayed.

Operation of a Solenoid Valve

Let’s look at how a solenoid valve works from the start of a cycle to the end. We’ll go through a typical system that uses a conventional intermittent duty oil burner main control in this example.


The main control relay pulls in, linking line voltage to the orange lead when the thermostat requests heat. The motor, ignition, and solenoid valve are usually linked in parallel, so they are all turned on at the same time.


A magnetic field is created when the valve coil is activated, forcing the spring-loaded steel valve piston to overcome the resistance of the spring and draw into the stem. The valve seat will now be farther away from the cut-off opening. The valve is now open.


The pump and the motor are approaching maximum speed. The pump rpm quickly rises when the valve is opened, generating enough pressure to propel the regulator piston to the open position. The oil then flows to the intake of the valve, via the aperture, and out the nozzle.

As it travels through the nozzle, the high-pressure oil is atomized, mixed with the blower air supply, and ignited by the electrode spark. The burner primary control is de-energized when a flame is formed and maintained until the temperature controller is satisfied.


The main control’s relay is de-energized, and line electricity to the orange lead is promptly turned off. The solenoid coil’s magnetic field diminishes almost instantaneously, and the spring-loaded valve piston closes, cutting off oil flow to the nozzle. The fire has gone out.


The motor speed quickly drops as a result of this action, allowing the pump regulator piston to shut. The shafts of the engine and pump come to a halt. This is the end of the cycle.


The oil solenoid valve is a flexible device that may be fitted to the fuel pump or the burner housing in a variety of combinations. Always verify the valve’s pressure rating to be sure it’ll work with the pump pressure you’re using. When correctly placed in situations where it is required, the solenoid valve may give a number of advantages that can help to ensure dependable and effective oil heating.

A quarter-turn on-off valve is known as a plug valve. The plug comes in several port types and can be cylindrical or tapered. Plug valves come in both lubricated and non-lubricated versions.

Non-Lubricated Plug Valve

A polymeric body liner or sleeve is put in the body cavity of non-lubricated plug valves. The polished, tapered plug serves as a wedge, pressing the sleeve against the body. The friction between the plug and the body is reduced by the non-metallic sleeve.


When little maintenance is required, non-lubricated plug valves are utilized instead of lubricated plug valves. Because they do not have a body cavity in open contact with the flow while switching, fouling liquids cannot be trapped or hardened, possibly clogging the valve, they can be utilized in particular services. There is no torque sitting on these valves.

Lubricated Plug Valve

Only inverted pressure balance lubricated plug valves will be utilized if the product permits the use of lubricant. The base oil and a viscosity improver, such as amorphous or fumed silica, are required in lubricants. They work effectively in procedures with mildly abrasive particles in the fluid. The tapered bores of the plug and body are matched to provide a reasonably large seat area. The plug bore is usually decreased, but the full port is accessible for slurry functions with significant solid content, where these valves are especially well suited. Full port valves are far more costly than reduced port valves, and they’re not usually utilized in hydrocarbon applications.


The lubricant or sealant creates a seal between both the plug and the body, protects the seating surfaces from corrosion, and functions as a lubricant, all of which helps to reduce the force necessary to open or shut the valve. The sealant is injected regularly, possibly every twenty procedures or after long periods of inactivity. It is possible to install an automated lubrication system. If the valve is not lubricated, it may become inoperable.


In most configurations, a jacking screw may be manually adjusted to elevate the plug off the seat. After such intervention, solids may become lodged between the plug and the seat, obstructing dependable shut-off. The sealant facility can occasionally be used to repair damaged seats back to service.


Lubricated plug valves are commonly utilized in filthy upstream applications where process fluid contamination is not a concern. The valves are, however, more costly, and heavier than ball valves. They’re also commonly employed as bypass valves for mainline ball valves, blow-down valves on valve stations, and kicker valves in gas pipeline systems. They can be made of unusual materials like duplex stainless steel and Inconel atop Inconel.


There is no torque sitting on these valves.


Double isolation plug valves may be used instead of two valves in series for double block and bleed non-piggable upstream applications when size and weight are a concern.

Eccentric Plug Valve

A plug valve with the plug sliced in half is known as an eccentric plug valve. The benefit of this design is that it provides a larger sitting force while reducing friction from the open to a closed state. Without a large increase in working torque, shut-off capabilities are increased. Torque is used to seat these valves.

Expanding Plug Valve

This expanding plug valve is a unique design wherein the plug is made up of many components that allow it to expand mechanically onto the cylindrical body by a wedging motion. Although pricey, these valves provide a real double block and bleed function in a single valve, which is great for preventing product contamination. These valves should not be utilized for maintenance reasons as a way of “double isolation,” as a single failure is still likely to impair both blocking functions.

Key design characteristics

As we know plug valves are the double valves with a cavity between the seats , or both above and below the stopper, and must satisfy the cavity relief requirements.


Non-metal-seated plug valves and non-lubricated plug valves with non-metallic sleeves used to handle combustible fluids might be equipped with an antistatic mechanism that ensures electrical continuity between the plug, stem, and valve body.

The engine lubricating system relies heavily on oil filters. These oil filters eliminate all the types of pollutants that might harm your motor engine in the long run


If left unfiltered, motor oil can get saturated with small, hard particles that can damage the surfaces of internal parts.


Bypass-Relief-Valve (BPRV) is included in all current oil filtering systems to prevent “extra oil usage” if and when the filter becomes blocked. A spin filter, in which the valve is an integrated component of the filter, and a cartridge filter, in which the valve is primarily part of the housing, are the two types of filters.


When the filter becomes clogged and the lubricant is unable to flow through the filter’s media, the Bypass-Relief-Valve is constructed with a predetermined opening pressure to enable free passage of oil. Pressure might build up without a bypass valve or if the valve doesn’t open correctly, causing the filter to break and the oil to flow. If the valve opens too fast or too frequently, tainted oil will flow into the engine, speeding up the wear of the engine’s surfaces. If the valve opens too late, the oil flow may get impeded, resulting in inadequate lubrication.


To ensure the longevity of your engine, the opening pressure is properly calibrated.


All aspects of LubChem, including the bypass relief valve, are supplied by LubChem to satisfy OEM specifications. It’s ideally suited to current engines’ high oil flow rates. Simply putting LubChem guarantees, that your engine is adequately protected by providing the proper quantity of clean lubricant.


Learn more about LubChem


LubChem provides high performance, high quality, and long-lasting lubricants and greases for extreme pressure or heavy duty. Along with our services we provide belief that you receive the best quality product for needs. Contact us now.

Plug Valves: Parts, Working, Types, Symbol, Applications, Advantages, and Disadvantages (With PDF)

A plug valve is a quarter-turn rotary motion manual valve. It uses a cylindrical or tapered plug (plug-shaped disk) to permit or prevent straight-through flow through the body. Plug valves offer a straightway passage through the ports so that fluid can flow through the opening plug with a minimum of turbulence. Flow can be in either direction with fully open or fully closed. The plug valves have been used in many different fluid services. Their performance is good in slurry applications. They are used in bubble-tight services as an on-off stop valve. They are used in air, gaseous & vapor services, Natural gas & oil piping systems, food-processing, nonabrasive slurry, vacuum, pharmaceutical services, and vacuum to high-pressure applications. They are good for on-off valves, diverting services, and moderate throttling. Initially, Plug valves were designed to replace gate valves as plug valves with their quarter-turn action can easily open and close against flow as compared to a gate valve. Plug valves are usually preferred for low-pressure–low-temperature services. Plug valves having body lining with materials like polytetrafluoroethylene (PTFE) can be used for corrosive chemical services. To handle abrasive and sticky fluids, special designs are required. Plug valves are usually found in sizes up to 18 in (DN 450) and in the lower-pressure classes [ANSI Classes 150 and 300 (PN 16 and 40)]. In this article, we will explore the parts, working principle, types, symbol, advantages, and disadvantages of Plug Valves.

Components of a Plug Valve

Plug valves have all the general parts such as stem, body, disc, and bonnet. It is different from other valves due to its plug disc design. The Plug Valve Body: The valve body has all the internal components of the valve. The body connects to the pipes through an end connection. The Plug valve Stem: The stem of the valve connects the disc (or disk) to the actuator. This helps in transferring the movement of the actuator to the plug disc thereby opening or closing the plug disc. The plug valve has a little stem that connects to the disc. The Plug valve disc The plug disc which is known as the tapered disc acts as a plug hence differentiating the plug valve and the globe valve. Out of all the valves, the plug valve, ball valve, and globe valve have some similarities. The major difference is in the way that how the disc looks like. The Globe valve has a cylindrical disc. The plug valve has a solid metal piece with tapered ends.

Plug Valve Ports

An important feature of a plug valve is its easy adaptation to multiport construction. In general, Multiport plug valves are used widely. They provide various benefits like:
  • Simplified piping and installation
  • More convenient operation than multiple gate valves.
  • Elimination of costly pipe fittings.
Depending upon the number of ports in the plug valve, a multiport plug valve can eliminate four conventional shutoff valves.
Plug valves has the following port patterns:
  1. Round opening: It has round ports in both plug and body.
  2. Rectangular opening: It has rectangular ports of the full bore section.
  3. Standard opening: In this, the area through the valve is less than the area of the standard pipe.
  4. Diamond opening: It has a diamond-shaped opening through the valve.
  5. Multi-port: with three or more pipe connections used for transferring services.
  6. Venturi design: It has reduced area opening with Venturi flow through the body.

Plug Valve Working Principle

Plug valve comprises a body with tapered or parallel seating into which a plug fits. The plug is formed with a port, the position of the port controls the amount of opening through the valve. Ports are known as the openings in the valve body through which fluid can enter or leave. A 90 degree of plug fully opens or closes the fluid flow. Plug valve is not as efficient as ball valves and can only operate fully open or closed. When the opening in the plug is in line with the inlet and outlet ports, flow continues through the valve. A pressure drop occurs through the reduced area of the plug port. However, with a full-area cylindrical plug the pressure drop is minimal. When the hand operator is turned to the full quarter-turn position (90°), the plug’s opening is turned perpendicular to the flow stream, with the edges of the plug rotating through the sealing device (sleeve, lubricant, etc.). When the full quarter-turn rotation is reached, the port is completely perpendicular to the flow stream, creating complete shutoff. In throttling situations, where the plug is placed in a midturn position, the plug takes a double pressure drop. The inlet port’s flow area is reduced by the turning of the plug away from the full-port position, taking a pressure drop at that point. The flow then moves into the full-port area inside the plug, where a pressure recovery takes place, followed by another restriction at the outlet port. Leakage is prevented through the seat by the compression of the plug against the sleeve or other sealing mechanism, while the packing or the collar–diaphragm assembly prevents leakage through the stem. With three-way valve arrangements requiring diverting flow, flow enters at the inlet and moves through the plug, which channels the flow to one of the other two outlets. When the plug is moved 90°, the flow is channeled to the other outlet. At a midway position, flow may be equally diverted to both outlets. With combining flow, flow is directed from two inlets to a single outlet. In order for some of these arrangements to occur, the plug must be turned by half-turn (180°) instead of the typical quarter-turn action. With larger plug-valve sizes [3 in (DN 80) or larger], the torque required for seal breakout may become somewhat excessive. This is caused by the larger contact surface between the plug and sealing device as well as any adverse operating conditions, such as a high process pressure, temperature extreme, corrosion deposits, etc. In this case, hand-levers are typically replaced with geared handwheels, which reduce the torque requirement significantly. The simple plug valve is suitable for low pressure, low-temperature applications and is made in large sizes of 250 to 300 mm. The main limitation of the plug valve is that if wide variations in fluid temperature are involved then differential expansion is inevitable, leading either to undue stiffness of operation or loss of pressure-tightness. The plug may be tapered, parallel and the movement may be plain or lubricated. Another variation is known as the ball plug valve, in which the plug is spherical, having circular ports rotating between circular seats of the concave section.

Types of Plug Valves / Plug Valve Types

In general, there are four types of plug valves. They are:
  1. Lubricated Plug Valves
  2. Non-lubricated Plug Valves
  3. Eccentric Plug Valve, and
  4. Expanding Plug Valve

Lubricated Plug valves:

These valves use lubricants or sealants to ease their operation over a wide range of operating pressure. The lubrication film which is used between plug and body provides a seal and that requires periodic lubricant injection. The sealant must be like that it does not get washed away with the fluid as the fluid can get contaminated and it should be able to withstand line temperature. These lubricants in plug valves are mostly plastic sealants. The use of effective sealant with properties such as proper elasticity, resistance to chemicals, and its ability to form an impervious seal around each body part is essential. The lubricating film also protects the metal surfaces between the plug and body from corrosion. Lubricated plug valves are manufactured in sizes ranging from DN 15 to DN 900. They are used in applications with pressures over 2500 psi.

Non-Lubricated plug valves:

These plug valves are usually used for lower pressure lines. These valves contain an elastomeric body liner or sleeve installed in the body cavity. The plug that is tapered and polished acts like a wedge and tends to press the sleeve against the body. Thus the sleeve reduces the friction between the plug and the body. There are three types of non-lubricated plug valves:
  • Lift-type plug valve
  • Elastomer sleeved plug valve
  • Fully lined plug valve
Lift type plug valve provides a mechanically lifting arrangement to disengage tapered plug from the seating surface to permit easy rotation. The lifting can be achieved by an external lever. The elastomer sleeved plug valve has an elastomer sleeve. It is a TFFE sleeve which surrounds the plug completely. The elastomer sleeve is engaged and locked in place through a metal body. This sleeve has less coefficient of friction and is also self-lubricated. Fully lined plug valve: These types of valves use inexpensive ductile iron or cast iron body. The body and plug of the valve are fully lined with Teflon in a way giving the valve the ability to resist corrosive fluids using iron as the body material.

Eccentric Plug Valve

This type of plug valve design uses a half plug. This design helps in applications requiring a higher seating force with minimal friction from open to closed position. Improved shut off capabilities is the main feature of the the torque seated valves. Eccentric plug valves find application in a wide range of flow control and isolation services. Some of the typical applications of eccentric plug valves are clean and dirty water, sewage, sludge and slurries, air, and other services.

Expanding Plug Valve

Expanding plug valves are complex in design. They use multiple components allowing the plug valve to expand mechanically and give it a true double block and bleed function in one valve. This types of plug valves uses a mechanism that rotates between the open and closed position and protects both seals from the flow path. The body and seals does not contact each other during rotation which avoids wear or abrasion to the seals. For applications not requiring double isolation, expanding plug valves are often used to prevent product contamination.

Plug Valve types by Pattern

Based on patterns, plug valves are categorised as follows:
  • Round opening- Full-bore round ports in both plug and body.
  • Rectangular opening with rectangular shaped ports of full-bore section.
  • Standard opening where the area through the valve is less than the area of the standard pipe.
  • Diamond port where the opening through the valve is diamond shaped.
  • Multiport with three or more pipe connections.
  • Venturi design with reduced area porting and featuring venturi flow through the body.
  • Short plug valves with reduced area ports and reduced face to face dimensions.
  • Vertical plug valves with reduced area seating ports and the plug passages reduced in section to form a throat.

Plug Valve Materials

Plug valves can be produced from a variety of materials; both metallic and plastic. The most common plug valve materials are
  • Steel
  • Stainless Steel
  • Bronze
  • Brass
  • Plastic, etc

Plug Valve Symbol

In P&ID the following plug valve symbol is used for identification and differentiating from other valves.
Fig. 3: Plug Valve Symbol

Pressure Balanced Taper Plug Valves

In larger taper-plug valves, pressure balanced plugs are fitted for very high static pressure applications. With a non-pressure balanced plug, line pressure in an open valve can find its way into the larger end chamber that exists below the plug. This creates a resultant force that tends to push the plug into its tapered seat causing a danger of taper locking. With a pressure balanced plug valve, the live line pressure replaces the sealant pressure by allowing the line to pressurize the small end chamber. A balancing force is generated which prevents the taper lock. The pressure balanced system consists of two holes in the plug connecting chambers at each end of the plug with the line pressure. The hole in the small end of the plug contains a non return valve. This enables sealant pressure to be built up if necessary, while allowing access of the line pressure to the small end chamber. Thus the pressure in the large end chamber always equals the line pressure and the pressure in the small end chamber is always equal to or greater than the line pressure which prevents the taper locking.

Advantages of plug valve

The main advantages of a plug valve are:
  1. It has a simple design and fewer parts
  2. It can be quickly open or close.
  3. This valve offers minimal resistance to flow.
  4. The use of multi-port designs helps in reducing the number of valves needed and permits a change in the flow direction.
  5. It provides a reliable leak-tight service.
  6. They are easy to clean which can be done without removing the body from the piping system.

Disadvantages of plug valve

The limitations or drawbacks of a plug valve are:
  1. As a large amount of friction is required to rotate the plug, which results in greater force to operate these valves.
  2. Actuators are required for larger valves.
  3. These plug valves cost more than ball valves which have a similar design.
  4. Pressure drop is more due to reducing port.

Codes and Standards for Plug Valve Design

The industry codes and standards governing the plug valve design, test and inspection are:
  • ASME B16.10-Face to Face and End to End Valve Dimensions
  • API 599 – Metal Plug Valves – Flanged, Threaded, and Welding Ends
  • API 6D – Specification for Pipeline valves
  • API 598 – Valve Inspection and Testing
  • API 6FA – Fire Test for Valves
  • BS 5353 – Specification for steel plug valves
  • BS 5188 – Specification for cast iron plug valves
  • MSS SP 61 – Pressure testing of steel valves
  • MSS SP 25 – Standard marking system for valves, fittings, flanges & unions
  • MSS SP 78- Gray Iron Plug Valves, Flanged and Threaded Ends

Applications of Plug Valves

As stated earlier, Plug valves are suitable for a wide range of services like Air, gas, vapor, slurry, mineral ore, sewage applications, oil piping systems, etc. They are suitable for vacuum as well as high pressure applications even though Plug valves are usually used in low-pressure-low-temperature services. The majority of plug valves are used:
  • for directional flow control, even in moderate vacuum systems.
  • for efficient handling of gas and liquid fuel.
  • for safe handling of extreme temperature flow, such as boiler feed water, condensate, and other such elements.
  • to regulate the flow of liquids containing suspended solids like slurries.

Plug Valve vs Ball Valve

Even though both the Plug valve and the Ball valve are quarter-turn rotary valves, they have few dis-similarities. The major differences between a plug valve and ball valve; i.e, Plug valve vs Ball valve is listed below:
Plug Valve Ball Valve
The disk of a plug valve is cylindrical or conical The disk shape in a ball valve is spherical
The disk size is comparatively larger. Disk size is smaller.
The Sealing surface is larger in plug valves. The Sealing surface is comparatively smaller in ball valves.
More torque requirement for plug valve operation. So, limited application of bigger size plug valves Ball valves provide torque free operation and suitable for all sizes.
Plug valves are heavier as compared to ball valves of the same size and rating. Lighter in weight.
Ease of maintenance. Difficulty maintenance.
Lifespan of plug valves is normally less than ball valves More lifespan.
Cost of plug valve is less. Comparatively expensive as compared to plug valves.
Plug valves are full port, thus allow full flow. Ball valves are available in full and reduced port.
Construction is simple. Ball valve construction is complex.
Plug valves provide better flow control as compared to ball valves.

Extended Reach Drilling in Alaska — Worth the wait

Hear about the historic firsts and challenges of preparing for and moving an innovative 9.5-million-pound rig 2,400 miles from Canada to Alaska and across the North Slope with the work completed in the midst of a pandemic and global economic crisis. The rig is currently planned to start drilling the Fiord West Kuparuk field in June 2021.