A Process Industry Stalwart - The Plug Valve

Lubricated plug valve.
(Flowserve Durco)

This article will focus on one of the oldest and most reliable (when properly applied) industrial valve types - the plug valve.

Fluid process control operations commonly employ pumps, piping, tanks and valves as the means of transporting, containing and controlling the fluid movement through a system.

Valves, of which there are many types, provide control over the flow rate, direction and routing of fluids in a processing operation. Flow can be started, stopped or modulated between zero and full rate using a properly sized and configured valve. Some valves enable media flow to be diverted to a selection of outlets, in lieu of a single inlet and outlet pair. Specialized valves regulate inlet or outlet pressure, or prevent fluid flow from going in an undesirable direction. All of these capabilities are packaged into differing valve product offerings that present a very large selection array to a process designer or engineer.

Non-lubricated plug valve.
(Flowserve Durco)

Industrial flow control valve types are generally classified according to the structure or arrangement contained within the valve body that provides obstruction to fluid flow. Some of the common types are ball, butterfly, gate, globe, and plug. Surely, there are more valve types, and this article is not intended to list them all. Some of our previous blogs have discussed selection considerations for gate, ball and butterfly valves.

Plug valves, like ball and butterfly valves, span from fully open to fully closed positions with a shaft rotation of 90 degrees. The “plug” in a plug valve is installed in the flow path within the valve body and rotated by means of a stem or shaft extending to the exterior of the body. Plugs are tapered toward the bottom and are fitted to a seating surface in the valve body cavity that prevents fluid from bypassing the plug. An opening through the plug, the port, can be shaped to provide particular flow characteristics. There are two main types of basic plug, lubricated and non-lubricated. Lubricated plug valves have a cavity into which a sealant is injected. The sealant provides a renewable seal between the plug and the body, prevents internal leakage, and protects the seating surfaces against corrosion. Non-lubricated plug valves utilize an elastomeric body liner or a sleeve in the body cavity that is pressed in to the body of the valve by the plug's wedge-like shape,  with the result of reducing the friction between the plug and the body.

Plug valve considerations:

• 90 degree rotation from open to closed provides fast operation.
• With proper configuration, can be well suited for frequent operation.
• Availability of corrosion resistant liner may provide comparative cost savings because valve body can be constructed of less expensive material.
• Design is simple and employs a low parts count.
• Valve can be serviced in place.
• Generally, low resistance to flow when fully open.
• Reliable leak-tight service due to tapered plug wedging action, replaceable sleeve, and injection of lubricant in some variants.
• Potential issues of concern for plug valve application include a short list of items.
• Higher friction in the plug closure mechanism may require comparatively higher operating torque than other valve types.
• Without a specially designed plug, generally not well suited for throttling applications.
• Rapid shutoff delivered by plug design may not be suitable for some applications where hammering may occur.

Share your fluid control application challenges with a valve and automation specialist. Leverage your own knowledge and experience with their product application expertise to develop an effective solution.

A Peek Inside a Valtek Mark One Control Valve with Piston Actuator

The video below provides a look inside the Flowserve Valtek Mark One control valve and identifies its major components.

The Flowserve Valtek® Mark One globe control valve is designed for liquid and gaseous services, and for permitting easy, fast and inexpensive maintenance.

The spring-cylinder actuated Mark One valve provides stiffness and maintains high positioning accuracy, repeatability, controlled high speed, and faithful response. The Mark One valve handles up to 150 psig supply air and has the thrust to shut off against much higher fluid pressures.

The Mark One valve is designed so the spring, supply air pressure and fluid pressure itself combine to produce exceptionally tight shutoff. A self-aligning seat ring further enhances the shutoff capability of the valve.

https://swansonflo.com
800-288-7926

Jorlon™ Structurally Modified Pure PTFE Diaphragm for Control Valves and Gas Regulators

Jorlon™ Diaphragm

Jorlon™ is structurally modified pure PTFE. It is manufactured by a proprietary technique where PTFE layers are combined and formed in a unique process to reduce the creep and cold flow associated with conventionally formed solid, or laminated PTFE or Teflon.

Jorlon™ is featured in all of Steriflow's valve product lines:

• Mark 978 Control Valves
• JSHM Manual Metering Valve
• Mark 96 Pressure Regulating Valves
• Mark 95 Back Pressure Regulating Valves
• Mark 96A, 96AA, 95A, 95AA Air Loaded Regulators
• J Series Clean Gas Pressure and Back Pressure Regulating Valves

Lifetime Warranty
Jorlon™ is warranted for a lifetime of use on our Mark 95, Mark 96, Mark 96AA, Mark 95AA regulators, MK978 Series control valves, J-series regulators, and the JSHM metering valve.

Product Applications
JorlonTM has been specified in biopharm applications including WFI, clean steam (up to 100 psig), buffers, acids, cryogenic liquids, clean utility gas, biological intermediates and final process fluids.

Customer Use
Since its inception, thousands of Steriflow valves with Jorlon™ diaphragms have been installed in systems which have been validated by the FDA.

Cycle Testing
Jorlon™ has been tested on a variety of Steriflow control valves on 45 psig (3 bar) continuous steam service to over 1 million full stroke cycles. One of those valves was further tested with an additional 100 Steam and vacuum cycles without failure.

Lab Testing
Lab tests comparing Jorlon™ to 316L diaphragms have shown continued life after exceeding the SST failure cycle count by more than 100 times.

Jorlon™ Material
Jorlon™ has been used by Steriflow for over 15 years. To date, not one valve has been returned due to diaphragm failure when operating within its use parameters. Jorlon™ has been nitrogen pressure tested to over 1200 psi without failure.

Flowserve Control Valve Product Guide (Valtek, Kammer)

Flowserve Control Valve

Flowserve general service control valves combine platform standardization, high performance, and simplified maintenance to deliver a lower total cost of ownership.

Flowserve delivers a broad range of general service control valves – linear and rotary – with pressure ratings of ANSI Class 150 to 4500/PN 10 to PN 640. These high-performance control valves offer greater reliability, precision control, and flow capacity, with significantly reduced cavitation, flashing, and noise. Quality production ensures increased process yield and throughput.

Because Flowserve general service control valves are constructed on global platforms using standardized parts and components, up-front engineering is held to a minimum. Simplified operation, maintenance, and service further ensure lower total cost of ownership.

Download your own copy of the Flowserve Control Valve Product Guide here or browse through the embedded document below.

Flowserve Control Valve Product Guide (Valtek, Kammer) from Swanson Flo

Wireless Process Control Instrumentation

Wireless Process Control Instrumentation Diagram

Manufacturing plants are continually under tremendous pressure with demands for safety, reliability, and efficiency. Unplanned shutdowns and outages have a huge impact effects on plant performance. Lost production, escalating energy costs, unexpected maintenance costs, and heightened safety concerns are the real outcomes of equipment failure. New, developing process technologies must mitigate these plant control realities.

Wireless process control technology is a serious contender in the ongoing effort to improve plant efficiency,  mitigate risk, and increase productivity. Today's wireless transmitters are available for monitoring virtually any process control variable including flow, pressure, level, temperature, pH, Dissolved Oxygen, etc. Very notably, in the harshest environments, these devices reliably transmit critical control data back to central control areas around the clock and without the need for human presence.

The argument for wireless instrumentation is very compelling when you consider installation convenience and cost savings.  Some cost savings estimates run as high as 70%  by eliminating wires and cables, as opposed to the cost when using cables for the same application. And most remarkably, wireless instruments provide additional safety and compliance benefits by keeping maintenance personnel out of dangerous or hazardous areas.

All manufacturing industries are faced with the realities of cost cutting as plant managers endeavor toward continuous process improvement. The need for better solutions is always present, and wireless process instruments certainly appear to fit the bill. But before widespread adaptation of wireless occurs, concerns about reliability, user comfort, and integration must be overcome. However, as plant managers see the downward pressure on deployment and maintenance costs, and as they see improved employee safety and smoother environmental compliance, adoption of wireless instrumentation will accelerate and eventually become ubiquitous in process control.

DelVal Flow Control - Ball Valves, Butterfly Valves, Actuators

DelVal Flow Control offers high quality butterfly valves, ball valves, and quarter turn actuators that provide smooth, controlled and dependable flow of fluids through pipelines in process plants.

Products Include:  

• Resilient seated butterfly valves 
• Lined butterfly valves 
• High-performance butterfly valves (double and triple offset) 
• Trunnion mounted ball valves 
• Floating ball valves
• Actuators

https://swansonflo.com 

800-288-7926

Valve Actuation 101: The Three Basic Types of Pneumatic Valve Actuator

Pneumatic valve actuators come in three basic design varieties:

1. Scotch-yoke
2. Rack & pinion
3. Rotary vane

All three types provide the same function - converting air pressure to rotational movement intended to open, close, or position a quarter-turn valve (ball valves, plug valves, butterfly valves, or other 90 degree rotational valves).

All three styles are available in either direct acting or spring return versions. Direct acting actuators use the air supply to move the actuator in both directions (open and close). Spring return actuators, as the name implies, uses springs to move the actuator back to its "resting" state. Converting from direct acting to spring return is done through simple modifications, typically just adding an external spring module, or removing the end caps from rack and pinion actuators and installing several coil springs.

Scotch yoke (Limitorque)

Scotch-yoke actuators use a pneumatic piston mechanism to transfer movement to a linear push rod, that in turn engages a pivoting lever arm to provide rotation. They come in a wide variety of sizes, but are very often used on larger valves because they are capable of producing very high torque output. Spring return units have a large return spring module mounted on the opposite end of the piston mechanism working directly against the pressurized cylinder.

Rack and pinion (Delval)

A rack & pinion pneumatic actuator uses opposing pistons with integral gears to engage a pinion gear shaft to produce rotation. Rack & pinion actuators (sometimes referred to as a lunch box because of their shape) tend to be more compact than scotch yoke, have standardized mounting patterns, and produce output torques suitable for small to medium sized valves. They almost always include standard bolting and coupling patterns to directly attach a valve, solenoid, limit switch or positioner. Rack and pinion actuators use several smaller coil springs mounted internally and provide the torque to return the valve to its starting position.

Vane actuators generally provide the most space savings when comparing size-to-torque with rack and pinion and scotch yoke. They have a reputation for long life because then contain fewer moving parts than rack and pinion and scotch yoke actuators. Vane actuators use externally mounted, helically wound "clock springs" for their spring return mechanism.

The practical difference between these three types of pneumatic actuators comes down to size, power, torque curve and ease of adding peripherals. For the best selection of valve actuator for any quarter turn valve application, you should seek the advice of a qualified valve automation specialist. By doing so your valve actuation package will be optimized for safety, longevity, and performance.