Showing posts with label pipeline valves. Show all posts
Showing posts with label pipeline valves. Show all posts

Wednesday, September 19, 2018

What is an Industrial Gate Valve?

Industrial valves
Industrial valves come in a wide variety of types and styles.
 (Image courtesy of Crane)
Industrial valves are used for flow control in industrial processes at specific locations in a piping system. Valves start, stop, throttle, or divert the process fluid flow. Valve application characteristics are diverse, resulting in a broad array of possible valve choices. Valve styles and types have evolved based on their performance, safety, effectiveness, and longevity.

Valve type generally refers to the means employed to control fluid flow, specifically the body style and orifice design. These valve characteristics are used to determine whether a valve type may be suitable for your process application. The most common valve types include gate and globe valves (referred to as linear valves) and ball, plug, and butterfly valves (referred to as quarter-turn valves). All these types of valves have numerous variations and customizations occurring within each type.

The Gate Valve

Gate valve diagram
Gate valve diagram.

Gate valves utilize a movable wedge, often round or rectangular, that is positioned as to restrict the process flow path. This wedge, referred to as the gate or disc, is connected to a valve stem which extends to the exterior of the valve body. Linear motion of the stem will position the gate within the valve body to provide some degree of obstruction to the process flow path. Fully inserting the gate into the media path will shut off the flow, while successively withdrawing the gate will increase the opening through which fluid can pass and allows for increasing flow rates. Seals are provided along the planar surfaces where the gate contacts the valve body.

Gate Valve Advantages
  • When fully open, these valves provide little or no restriction to fluid flow. 
  • This valve type provides a straight through passage.
  • Gate valves can be employed bi-directionally, with flow control effectively available in both directions.
  • Installation space dimensions along the flow path are minimal.
  • Because the gate movement is perpendicular to the flow direction, the energy required to move the gate is generally low, allowing smaller actuators.
  • Closure of gate valves is comparatively slow to other types of valves, reducing the physical shock (hammering) in the piping system.
Additional Gate Valve Application Considerations
  • Valve seals are exposed to the fluid flow as the gate opens. The effects of the process media velocity and media corrosiveness on the seal material may cause deterioration at an unacceptable pace, particularly in throttling applications.
  • Gate valve stems generally extend substantially from the valve body, as they must accommodate the mounting of any required actuator and the entire range of motion of the gate. Some installations may not be able to provide the needed space for this arrangement.
  • The slower speed at which gate valves open and close may not be suitable for some applications.
  • Gate valves are generally not recommended for throttling the process flow, and using them in control applications could  result in gate vibration. There is also concern about expedited seal wear due to the exposure to higher process media velocities while throttling.

Wednesday, February 7, 2018

Plug Valves - Right For Your Application?

industrial plug valve with manual operating handle
Plug valves incorporate design features making them
a positive choice for many fluid process applications.
Image courtesy Fluoroseal, Inc.
There are common components to be found on almost every process system that involves fluid control. Regardless of the operation's scale, pumps, piping, tanks and valves are likely to be part of the 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.

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. This article will focus on one of the oldest valve types, the plug valve.

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 often 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 numerous variants of the basic plug valve which may make it suitable for particular applications. One common variant is the lined or sleeved plug valve, with an insert or interior lining of material that creates an isolating barrier between the valve body and the media. This allows use of less expensive materials for the body construction that may be otherwise subject to corrosion by exposure to aggressive media.

Positive attributes of plug valves.

  • 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.

  • 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.

Tuesday, November 28, 2017

Pipeline Cyber Security

binary stream representing industrial process control network data transfer and cyber security threat
Cybersecurity is a process control challenge that consistently evolves as new technologies come into use and new threats emerge. Since process control methods are constantly developing, the protective measures need to match the rate of change to ensure adequate levels of protection are in place. Pipelines used in the oil and gas industry, as well as in the transportation of a multitude of liquid and gaseous products, account for more than 2.3 million miles of process piping in the United States.  Natural gas pipelines are commonly monitored and controlled by, for example, programmable logic controllers or other microprocessor and communications based systems, responsible for flow regulation and various process conditions. Because of the prevalence of these systems, they are a target of increasing attacks, on both PLCs and other SCADA related devices, such as compressors, remote terminal units, communication networks, and other critical process infrastructure elements.

While developments in technology have provided operating advantages and improvements to the process industries, the more complex and advanced the systems may also increase the exposure to malicious penetration and mischief by unauthorized parties (hackers). Because of this, diligence by industry professionals, while always a strong component of protecting against outside threats, has been augmented via new guidelines meant to better prepare all process operators against more coordinated cyber-attacks.

Basic preventative measures, such as a firewall, are no longer a sufficient bulwark against the increasing threats. Instead, the entire process must be evaluated and monitored so that each individual piece of the network is understood fully. If a part of the system starts behaving in an abnormal way, then an understanding of what that specific PLC or component affects must be immediately known. The most effective protective programs will be able to function without needing any downtime, and will also be able to learn the network easily. Whenever the defense program gets triggered, it needs to not only provide a general alert to the process operator, but must also be able to provide context so that the previous knowledge of how the system works can be applied to mitigate the current problem.

Currently, the oil and gas industry has transitioned to what is being termed a ‘holistic’ approach to cyber defense. In order for the best security possible to be employed, the human element of process control must function in tandem with the autonomous programs. The human component of process operation, where it exists, can be unpredictable and present vulnerabilities that may not be known or anticipated. Everything must be considered.

Industrial process operation involves many areas of risk, with cyber attack being just one. The right kind of planning and response to risk can mitigate the potential impact. Security efforts, technology, and knowledge must keep pace with threats which emerge to process pipeline security. Mountain States Engineering and Controls participates in the oil and gas industry throughout the western U.S.

Wednesday, September 20, 2017

Trunnion vs. Floating Ball Valves

trunnion mount ball valve for industrial pipeline use
Trunnion mount ball valves have upper and lower support
points for the ball.
Image courtesy International Standard Valve, Inc.
The design, construction, and function of a ball valve is generally well understood in the industrial fluid processing arena. Ball valves provide reliable quarter turn operation, compact form factor, and tight shutoff capability, making the ball valve a preferred choice for many applications. Some ball valves also provide shutoff of fluid flow in either direction. A primary valve trim design feature permits grouping of the many variants of industrial ball valves into two categories, distinguished solely by the way in which the ball is mounted in the body.

Floating ball valves use the seats and body to hold the ball in place within the fluid flow path, with the force of directional flow pushing the ball against the downstream seats to produce a tight shutoff seal. Many floating ball valves are capable of flow shutoff in either direction. The ball is rotated by a shaft connected at the top which extends through the pressure enclosure of the valve for connection to a handle or automated actuator. The floating nature of the ball limits the applicability of this design to smaller valve sizes and lower pressures. A some point, the fluid pressure exerted on the ball surface can exceed the ability of the seats to hold the ball effectively in place.

Trunnion mount ball valves employ the stem shaft and, you guessed it, a trunnion to rigidly position the ball within the body. The shaft and trunnion, connected to the top and bottom of the ball, establish a vertical axis of rotation for the ball and prevent it from shifting in response to flow pressure. The trunnion is a pin that protrudes from the bottom side of the ball. It sits within a bearing shape, generally cylindrical, in the base of the body.

Because of their structural design, trunnion mount ball valves are suitable for all pressure ranges and sizes.They are used by many manufacturers as a basis of design for their severe service ball valve offerings. A trunnion mount ball valve can also be advantageous for applications employing valve automation. Since the ball is not held in place by a tight fitting seal arrangement, operating torque tends to be lower for comparably sized trunnion mount valves, when compared to floating ball valves.

On page 3 of the brochure included below, the exploded view of a trunnion ball valve shows the location of the trunnion assembly.

Whatever your valve application challenge, share it with an industrial valve expert. Leverage your own process knowledge and experience with their product application expertise to develop an effective solution.


Tuesday, November 10, 2015

Pipeline Strainers: Proper Selection and Application

Pipeline Basket Strainer Cutaway View
Basket Strainer
Courtesy Spirax Sarco
Pipeline strainers are one of those simple devices that perform a critical role in maintaining the smooth operation of any piping system. They are found in any operation that has fluid moving through a pipe, and their proper selection and application is the subject of a great tutorial authored by the experts at Spirax Sarco, a premiere manufacturer of specialties for industrial piping systems.

One of the basic tenets of industrial process control operations is to maintain a specified function or outcome, to keep things working. Reduced to its simplest, the function of a strainer is to trap materials flowing in the pipeline that should not be there. Rust, scale, joint compound, and particulate materials can impact the function of valves and other elements in the system. A strainer will trap and hold undesirable material, for removal at a later time.

The attached article is excerpted from the company's extensive tutorial library, which you can access by contacting an application specialist. That same application specialist can provide additional detail at any level you need, as well as work with you to meet application challenges and improve your industrial or commercial operations.


Tuesday, July 21, 2015

Selecting the Right Valve Type - Plug Valves

Valves are the primary fluid flow control device employed in the industrial process control arena. The widely varied applications and requirements have led to an almost daunting array of vendors. valves and options from which to choose. For your particular project or application, the selection candidate pool can be shrunk down to a manageable size if you first select the type of valve that will best suit your needs.

industrial plug valve internal part
The "Plug" in a Plug Valve
Courtesy Fluoroseal Inc.
Valves are generally used to start, stop, redirect, or throttle (control at some intermediate level) the flow of a fluid. They may also be tasked with preventing fluid flow from going in an undesirable direction or regulating pressure. Industrial flow control valve types are generally classified according to the structure or arrangement within the valve body that provides the 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 ball, butterfly, and gate valves. Let’s look at one of the oldest valve types, the plug valve.

Plug valves are similar to ball and butterfly valves, with their rotational movement of 90 degrees from the fully open to the closed positions. The “plug” in a plug valve is installed in the flow path within the valve body and rotated by means of a stem extending to the exterior of the body. Plugs are often tapered toward the bottom and are fitted to a seating surface in the valve body cavity. An opening through the plug, the port, can be shaped to provide particular flow characteristics. There are numerous variants of the basic plug valve which may make it suitable for particular applications. One common variant is the lined plug valve, with an interior lining of material suited to provide a measure of corrosion resistance for special media applications.

industrial plug valve
Industrial Plug Valve With Manual Operation Handle
Courtesy DHV Industires
What are the general positives for plug valve application?

  • 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.

What are some potential negatives for plug valves?

  • Higher friction in the closure mechanism may require comparatively higher operating torque than other valve types.
  • Generally not well suited for throttling applications without special design modifications.
  • Rapid shutoff may not be suitable for some applications where hammering may occur.

As part of your own assessment and selection process, share your application requirements and concerns with an experienced sales engineer. Their product knowledge and application experience can provide the additional input needed to make the best choice for your project.

Friday, June 26, 2015

Selecting The Right Valve Type - Ball Valves

Applications that can be characterized as industrial fluid handling or process control are vast in number and variety, each being highly specialized and customized to specific circumstances. It’s no surprise that, given the array of potential application conditions, there are countless different valve arrangements, types, and technologies to choose from.
Industrial Ball Valve
Large Industrial Ball Valve
Courtesy HS Valve Co.
Ball valves, like many valve types, are named for their closure mechanism. A spherical shaped element is placed in the fluid flow path, with the ability to rotate its position around an axis. The axis is a shaft or other device that connects to an actuator on the exterior of the valve and flow path. The actuator can be a simple handle or an element of a valve automation system. The “ball” in the ball valve has an opening through its center, usually round to mimic the shape of the connected pipe. As the ball is rotated, the opening aligns with the inlet an outlet of the valve body, allowing fluid to pass. A counter-rotation that aligns the opening with the sides of the valve body, away from the flow path, stops the fluid flow. So, compared with other valve technologies, when would a ball valve be a preferred application choice? Here are some points to consider.

Application advantages of ball valves:

  • Leak-proof service
  • Well suited for processes requiring only full flow or no flow operation.
  • Rapid open and close action, requiring only 90 degrees of rotation from fully open to fully closed.
  • Comparatively light weight and small size.
  • Wide range of construction material options for body, ball, and seals make them suitable for many applications.
  • Require only moderate force to control valve position.
  • Flow path opening in the ball will often be “full port”, providing same cross section as the connected pipe and adding very little restriction or pressure drop to the flow.
  • Low maintenance, with no lubrication required.

What considerations might be cause to consider a different valve type?

  • There can be some residual fluid trapped in the valve when it closes.The trapped fluid will be released when the valve is opened. Consider what impact, if any, this may have on your process.
  • Balls valves are generally not suited for throttling applications. When partially open, the seals that surround the ball are exposed to the flow velocity and can deteriorate quickly.
  • Valve seals are usually elastomeric materials. Verify seal materials are compatible with the fluid type, character and operating temperature.

These comments are general in nature and there are some specialized ball valve designs that have overcome some of the general disadvantages noted here. Have a conversation with a valve specialist about your application and benefit from their experience and knowledge.