Category Archive: Check Valves

PDC^® Valves vs. Piston Check Valves

Pulse-dampening check valves, or PDC^® valves, are designed for installation on the discharge side of a gas or air reciprocating compressor and feature a pulse-dampening chamber. With this pulse-dampened design, during the momentary pressure and flow increases and reductions that occur with a reciprocating compressor’s cycles, the PDC^® valve’s disc remains in the open position, accommodating flow variations and eliminating chatter.

Allowing for either horizontal or vertical installation, these spring-assisted, nozzle-style check valves are used for air or gas and come in line sizes of 2″ to 26″ and ASME Classes 150 to 1500. As for material composition, the one-piece body of this flanged valve is available in either carbon steel or stainless steel, while the center guided trim is composed of stainless steel. You can choose between RF flanged ends or RTJ ends.

These high-performance silent check valves comply with API 6D, a specification set forth by the American Petroleum Institute to govern valve design, production, and testing for natural gas and petroleum applications. They also adhere to the standard ASME B16.10 face-to-face dimensions, as specified by the American Society of Mechanical Engineers.

Compared to piston check valves, PDC^® valves offer multiple advantages. Read on to learn more about these valve types and how they differ to determine which is the best option for your needs.

Piston Check Valves

Another variety of check valves is the piston check, which can be used in gas or liquid piping systems. This valve type functions by using a weighted piston, gravity, and backflow pressure. The piston rises up as a result of forward fluid flow within the valve, but when it experiences backflow pressure, spring force pushes the piston seal into the seat to prevent reverse flow.

Some differentiating factors are that with the fluctuations in pressure, such as from a reciprocating compressor, the constant hammering of the piston is not only quite noisy, but over time, the continuous wear the valve incurs can reduce its performance and ultimately lead to premature wear, constant maintenance, or even failure. The internal flow of the piston check is considered a tortuous path, which affects pressure drop. Additionally, the piston check has multiple pressure-retaining components (leak paths), whereas the PDC^® is a one-piece body.

DFT^®’s PDC^® Valves Are Built to Handle Reciprocating Compressor Discharge

At DFT^® Inc., we manufacture our PDC^® silent check valves for longer service life and quieter operation. The dampening chamber mitigates a compressor’s pulsed discharge for significant reductions in the wear and tear a piping system will experience. The valve’s unique shape offers the additional benefit of normalizing fluid flow exiting the check valve.

When you’re operating a piping system with an integrated reciprocating compressor, for example, this can cause high-frequency pressure cycling. An installed piston check valve would experience greater wear, impacting additional down-line systems, whereas the PDC^® valve offers better protection and more dependable functionality for your application and equipment.

Learn More About Our PDC^® Valves

Choosing PDC^® check valves from DFT^® over piston check valves can enhance the performance, reliability, and longevity of your piping system. This generally equates to a better return on your investment over the lifetime of the valve.

As a world-class manufacturer of control and check valves, DFT^® has the multi-industry experience, the resources, and the commitment to excellence and innovation required to produce high-quality valves that address the challenges of each of our customers. We offer an extensive catalog of silent check valve options for solving problems such as water hammer. In addition to our PDC^® model, we also have the following available:

• Threaded/socket weld check valves
• Wafer check valves
• Flanged check valves
• Butt weld check valves
• Sanitary check valves
• Restrictor check valves
• Vacuum breaker check valves
• Nickel-aluminum bronze (NAB) check valves

Whatever your application, DFT^® is here to help you find the right valve for your unique requirements. Contact our team today to learn more about the PDC^® silent check valve difference. You can also explore our PDC^® product page or view a 3D animation of the PDC^® pulse-dampening effect.

Join Us for an Exclusive Webinar on Check Valve Applications for LNG Service

Title: Check Valve Applications for LNG Service
Presented by: DFT Inc.
Hosted by: GlobalSpec
Date: September 18, 2024
Time: 10:00 AM EDT (7:00 AM PDT / 4:00 PM CEST)

REGISTER HERE

As the demand for Liquid Natural Gas (LNG) continues to rise, understanding the infrastructure behind this vital energy resource is critical for engineers and industry professionals. LNG is a key player in today’s energy markets, known for its efficiency in storage and transport, making it an attractive option for power generation, industrial use, and transportation.

LNG’s operating conditions — including cryogenic temperatures, high pressures, and flow dynamics — place specific requirements on the equipment used in its processing systems. That’s why selecting the right check valve is paramount for ensuring system reliability and avoiding costly disruptions.

This webinar, presented by DFT and hosted by GlobalSpec, will provide valuable insights into the application of spring-assisted non-slam check valves within LNG service. The session will feature Arie Bregman, a seasoned valve industry expert with decades of experience in valve engineering, as he explores how check valves function within LNG processes and why their proper installation and sizing is critical for efficient system performance.

Why Should You Attend?

The webinar is geared toward valve professionals, engineers, and plant managers who are involved in LNG systems and valve selection. Attendees will gain practical insights that can be directly applied to improving operational reliability and efficiency.

Key Topics to be Covered:

• Understanding LNG Fundamentals: A brief introduction to the basics of LNG, its properties, including the processes and equipment used in liquefaction, storage, and transportation.
• Check Valve Applications in LNG: Gain insights into where and how check valves are used within LNG systems, focusing on key applications that optimize system efficiency and prevent flow disruptions.
• Optimal Valve Placement: Learn how strategic valve placement within LNG systems can significantly reduce wear, tear, and potential failures.
• Importance of Valve Sizing: Sizing check valves correctly can prevent common operational issues such as chattering and improper flow control. We’ll guide you through the critical considerations in valve sizing to ensure valves perform optimally.
• Industry Standards & Compliance: Familiarize yourself with the latest industry standards and specifications, ensuring your projects meet regulatory requirements and adhere to best practices.

Meet the Expert: Arie Bregman

Our speaker, Arie Bregman, brings nearly five decades of experience in the valve industry. From his beginnings with Nibco to significant roles at Jamesbury, Metso/Valmet, and DFT, Bregman has established himself as a respected voice in valve engineering. He holds a Master’s Degree in Mechanical Engineering from Worcester Polytechnic Institute and has served in leadership roles within the Valve Manufacturers Association of North America. His technical expertise and commitment to industry education make him the perfect guide to walk you through check valve applications in LNG service. DFT is pleased to welcome him back to present this special webinar on Check Valve Applications for LNG Service!

Don’t Miss Out!

Whether you’re a seasoned professional optimizing your current systems, or a valve professional seeking to deepen their understanding of valve applications within LNG processes, this webinar will provide insights about proper selection and application of check valves within LNG services. By attending, you’ll walk away with actionable knowledge to improve the efficiency and reliability of your operations.

Register now to secure your spot in this must-attend webinar on September 18, 2024. 

Can’t make the date? Register and you will be notified when the webinar is available to watch on-demand.

Severe Service Check Valves

DFT® manufactures check valves for many applications, including severe service applications. Typically, when engineers think of severe service, they think of high temperatures and/or high pressures.  However, severe service applications also include high cycling applications. We are going to explore two high cycling applications, including the challenges and DFT®’s severe service valve solutions.

Digester Service

The paper pulp digester is the primary equipment used in the production of chemical pulp. It is used to cook raw materials for papermaking (e.g., wood, grass, bamboo, and others) to produce pulp mainly containing cellulose by chemical interaction with the cooking liquor.

This process includes steam injection at up to 150 PSIG. The steam is pulsed into the digester several times per hour. While 150 PSIG is not considered severe, the constant pulsing can take a toll on equipment.

Digester Solutions

Several end users have experienced premature failure of traditional swing-type check valves in this application. When the swing check valves fail, the black liquor used to break down the pulp and the pulp itself would migrate upstream past the failed swing check and damage upstream piping and equipment.  

The end users reached out to DFT® to develop an Axial Flow Non-Slam Check Valve solution to this problem. DFT® developed several styles of severe service check valves with special construction to handle this high cycling application. The DFT® solutions include the GLC® SS short-pattern flanged check valve, the Excalibur® SS a B16.10 long-pattern flanged check valve, and the WLC® SS wafer-style check valve.

All of these check valve styles have upgraded internal materials selected to withstand constant high cycling. The upgraded materials include 17-4 trim with a Xylan-coated one-piece welded disc stem assembly, 17-4 bushings, and an X-750 spring.

Compared to only getting several months of service life with the swing check valves, end users now get extended years of service life with the DFT® Axial Flow Non-Slam Digester Severe Service Valve solution.

Boiler Feedwater Service

All power plants—including natural gas-fired, coal-fired, and nuclear power plants—have boilers. The boilers generate steam to power turbines that generate electricity. Water must be heated in boilers to generate steam. The water is delivered to the boilers by boiler feedwater pumps. 

Boiler feedwater is typically in the range of 180 °F to 225 °F.  These temperatures would not be considered severe. However, depending on the design of the system in power plants, the temperature may be even higher, often 300°F to 350°F , especially if feed water is preheated by economizers or heaters using steam from the turbine or other heat recovery processes. Feedwater pump discharge pressures can vary between 700 and 1400 psi depending on boiler demand.

Check valves are installed between the outlet of the boiler feedwater pumps and the inlet of the boilers and/or deaerators. The check valves are installed to prevent backflow out of the boiler that can damage expensive feedwater pumps and other upstream equipment. Not only is this a high-cycling operation, but it is also a high-pressure application with varying pressures depending on boiler load. This is a very demanding application. As with the digester application, traditional swing checks typically experience a high failure rate in this application.

Boiler Feedwater Solutions

DFT® developed the WLC® BF specifically for boiler feedwater applications. The WLC® BF has upgraded hardened materials selected to withstand high pressure, pressure swings, and high cycling. The upgraded materials include a WL9 body, a 4 ribbed body construction, greater wall thickness, 410 trim, a one-piece welded disc stem assembly with Colmonoy-coated stem, carburized bushings, and an X-750 spring.

Compared to only getting several months of service life with the swing check valves, end users now get extended years of service life with the DFT® Axial Flow Non-Slam Boiler Feedwater Severe Service Valve solution.  

Valve Types

DFT® offers the following valve types for digester, boiler feedwater, and other severe service applications. These valves are constructed from high-quality, heavy-duty materials with tight seals to withstand the harsh operating conditions of their application:

• DFT® Model WLC® BF (Boiler Feed): The DFT® Model WLC® BF wafer style check valve is for severe duty boiler feed service applications and other severe duty applications.
• DFT® Model GLC® SS: The DFT® Model GLC® SS is a severe service short-patterned flanged silent check valve designed for digester applications and other severe service applications. 
• DFT® Model WLC® SS: The DFT® Model WLC® SS is a severe service wafer style check valve for digester applications and other severe service applications.
• DFT® Excalibur SS: The DFT® Excalibur SS is a severe service flanged silent check valve for digester applications and other severe service applications. This valve is B16.10 and a  direct replacement for a swing check valve.

Severe Service Check Valves by DFT® Inc.

Severe service applications require specialized valve solutions. DFT® Inc. offers an extensive product line of robust severe service silent check valves specifically designed for these high-pressure and high-temperature environments. We are certified by ISO 9001:2015 and many other valve standards such as 3-A Sanitary Standards, Manufacturers Standardization Society (MSS), American Petroleum Institute (API) SPEC 6D, and European Pressure Equipment Directive (PED) to provide quality, long-lasting valves you can depend on.

Request a quote for your severe service valve solution today.

Check Valve Selection 101: Types & Applications

Check valves, sometimes called non-return valves, are valves with two openings or ports that allow fluid flow in only one direction. Fluid enters through one port and exits the valve through the other. Industrial fluid systems in power plants, chemical plants, water and wastewater treatment facilities, oil fields, refinery applications, and other industries rely on check valves to prevent fluid flow back to the source. For instance, check valves are often used to transfer fuel and an oxidizer in separate lines to a mixing vessel without the fuel or oxidizer flowing back into the initial gas or oxidizer cylinders. 

Selecting the right check valve for a specific application is essential to achieving optimal performance, reliability, and service life. Here, we will explore the various check valve types and applications to help you decide on the best option for your project.

Important Check Valve Selection Criteria

When selecting a check valve for an application, consider the following:

• Initial Costs: Consider the cost of the valve and any installation costs associated with the check valve.
• Maintenance Costs: The cost of maintenance or repairs can vary depending on the complexity of the valve. Improper, oversized check valves can add dramatically to life cycle maintenance costs.
• Head Loss and Energy Costs: Head loss is a characteristic of check valves determined by the internal valve design and degree of opening. Restriction in the valve opening (compared to the pipeline opening) will result in increased head loss, which can lead to higher energy costs.
• Non-Slam Characteristics: Proper valve selection is critical in preventing water hammer and slamming during operation. Consider a check valve that offers compatible closing characteristics to the dynamics of the pumping system.
• Fluid Compatibility: Certain valves are designed for different fluid viscosities, sediment, and particles. Select the valve that is compatible with the medium passing through it.
• Sealing Ability: Consider the proper sealing for your application, whether it’s gas-tight, bubble-tight, or drop-tight sealing.
• Flow Characteristics: Every check valve has its distinct flow characteristics. Matching the right characteristics to your needs can minimize the potential for reverse flow or surges on sudden pump shutdown.
• Valve Size and Pressure Rate: Check valves come in a variety of sizes and pressure classes. Ensure your valve is sized appropriately for the system’s flow rate and can withstand the operating pressure. Undersized or oversized valves may lead to inefficiencies or even system failure.
• Materials Selection: Based on certain criteria such as compatibility of the fluid type, temperature, and corrosiveness, material selection is crucial for the reliability of the valve.
• Installation Orientation: Consider the orientation of the check valve installation. Some check valves cannot be installed both horizontally or vertically.
• Application Considerations: Different applications have unique requirements, such as sanitary standards for food or fire safety for oil and gas. Ensure your check valve complies with any specific industry regulations.

Types of Check Valves and Their Applications

There are several types of check valves designed for distinct applications. Some of the most common check valves include lift, swing, and ball check valves.

Lift Check Valves

Lift check valves are economical, automatic valves with no external moving parts for reliable operation. Specific types of lift check valves include nozzle check valves, in-line check valves, and piston check valves. The main closure mechanism in a lift check valve is typically a disc that lifts off the valve seat when subject to inlet pressure, allowing normal fluid flow past the disc and seat, then through the outlet port. The motion of the disc is guided in a straight line, so the valve can later reseat properly. A spring or gravity moves the disc back into the seat when the upstream fluid pressure drops, stopping the fluid flow. DFT® check valves can be installed in any orientation: horizontal, vertical flow up, or vertical flow down. These types of valves are commonly found in applications where backflow prevention is critical.

Swing Check Valves

Swing check valves are one of the most common types of check valves due to their low cost. Because the valve operates entirely from flow pressure and gravity, it relies on the change of flow direction to close. This means swing check valves can only be used for horizontal or vertical “up” lines and are very susceptible to slamming and water hammer. These types of valves are commonly used in wastewater, sewage systems, and predictable flow water pumping applications.

Ball Check Valves

Ball check valves are often very small and simple in that the closing member is a spherical ball and the valve has no external components. The rotation of the ball during operation prevents particles from getting stuck on the ball. Some designs are spring-loaded and some do not have springs, instead relying on reverse flow to move the ball to the seat for sealing. Ball check valves are used in many applications and are often found in liquid or gel mini-pump dispenser spigots, hydraulic systems, and sprayer devices.

Contact Our Experts for Your Check Valve Needs

With many check valve types to suit various applications, it is vital to consider your fluid system’s needs when selecting the best check valve. Some of these deciding factors include cost, fluid compatibility, sealing, non-slam characteristics, and installation orientation. DFT® manufactures world-class silent check valves and severe service control valves for critical industries, from oil and gas to food and beverage to wastewater processing. We pride ourselves on collaborating closely with customers to solve their unique challenges. Our check valves are world-renowned for eliminating or preventing water hammer issues in diverse fluid systems. 

Browse our catalog of check valves to find the best product for your system. Additionally, you can download our eBook, Design for Flexibility: Key Considerations to Make When Designing Fluid or Gas Flow Systems. Contact us or request a quote to speak with a specialist about your check valve needs. 

Webinar Q and A: Carbon Capture and Role of Engineered Check Valves

As a follow-up from our webinar “Carbon Capture & the Role of Engineered Check Valves“, we are sharing, in this post, a few of the questions received from the audience.

During the webinar, we discussed what carbon dioxide is and how it impacts the environment, the critical methods of capturing carbon dioxide, how carbon dioxide is transported from producers to storage sites, technologies involved in carbon dioxide sequestration (storage), and how carbon dioxide is used for enhanced oil recovery.

We also explored the selection of appropriate check valves within the different carbon capture processes, including valve materials and pressure classes, highlighting their importance in maintaining optimal system performance and efficiency.

This webinar was presented by Stephen O’Neill, Director of Sales & Marketing at DFT^® Inc.

If you missed this webinar, you can now view it on demand from the DFT^® website, just click this link.

Below, our host answers a variety of questions that came in during the webinar:

Q: What is the difference between WLC^® BF and WLC^®?

A: The WLC^® BF was engineered for the extreme conditions of boiler feed applications. The WLC^® BF body comes standard as WC9 material with 410 trim in class 600 and 900/1500, 2 1/2″ to 10″. The WLC^® materials available are Carbon Steel or Stainless Steel and sizes range from 1″ to 10″ in classes 150 to 2500.

Q: DFT^® PDC^® valve, is this designed to be used entirely without a pulsation dampener or does DFT^® still recommend the use of a separate device?

A: The PDC^® has a built in pulse dampening chamber so there is no need for a separate pulsation dampening devise.

Q: What are the primary advantages of Excalibur^® over GLC^® designs?

A: The primary differences between the Excalibur^® and the GLC^® are that the Excalibur has a 2-piece body and ASME B16.10 face-to-face dimensions, a direct replacement for a swing check valve. The GLC^® has a short patterned body, therefore a lesser weight than the Excalibur^®. The GLC^® also meets API6D and is available in a larger range of sizes than the Excalibur^®.

Q: Which plant absorbs co2

A: In general plants remove carbon dioxide from the air naturally, and trees are especially good at storing CO2 removed from the atmosphere by photosynthesis.

Q: Do you have any mining applications with DFT^® Valves?

A: Yes, DFT^® has installations of check valves in many mining applications such as Autoclaving, mine dewatering, pump isolation, discharge, along with many others. We have the following resources on Mining that can be downloaded from our website:

An application guide with a section on Mining here:
DFT-Check-Valve-Application-Guide-2.pdf

Also, you can find success stories on dewatering and water hammer in mining here:
DFT_Mining-AppGuide_1-1.pdf

Q: Can the springs on the non-slam axial flow check valves be modified by factory to crack at a higher DP?

A : Yes, DFT^® is able to custom size the internals of our valves to your application, which does include being able to modify cracking pressures as needed.

Q: What is the value of stiffness of springs

A: Spring rate (K) is the proportion of a spring’s force (pounds or newtons) to one unit of travel (inch or millimeter). It is a constant value which helps to calculate how much load you will need with a specific distance traveled and it will also help you calculate how much travel you will achieve with a certain load.

Q: Is there a standard guideline on where to install check valves in piping systems?

A: In keeping with generally accepted piping and valve installation guidelines, the DFT^® Axial Flow, Nozzle Check Valve should be installed a minimum of 5 diameters downstream of a flow impediment, i.e. valve, reducer or bend etc, to ensure a good flow pattern at the entry to the check valve. The DFT^® Axial Flow, Nozzle Check Valve should also be installed at least 5 diameters upstream of a bend or reducer to allow flow to even-out and avoid choked flow conditions which can prevent the full opening of the check valve.

DFT^® has a technical sheet with diagrams that is available on our website in the resources section that can be downloaded. Go to WWW.dft-valves.com to download

Q: What advantages do axial flow non-slam check valves have versus swing check in reducing the effects of water hammer?

A: Swing checks rely on gravity or reverse flow to close and these conditions contribute to water hammer. Axial flow check valves are designed to close upon decreasing differential pressure, not reliant on reverse flow. This reduces or eliminates the likelihood of it slamming shut.

Axial flow, spring assisted, non-slam check valves can be installed horizontally or vertically flow up or flow down, whereas swing checks cannot be installed vertical flow down.

Q: What does Sweetened natural gas mean?

A: Gas Sweetening is a process that removes Hydrogen Sulfides (H2S) and is sometimes referred to as amine treating.

Resulting in Sweet Gas, which is non-corrosive, less acidic, and requires little refining.

Whereas Sour Gas must be sweetened to remove H2S and CO2, which have a corrosive effect on gas pipelines and is toxic to humans.

Q: Why is valve sizing important?

A: The most appropriate-sized valve must be chosen in order to render the best service. An undersized valve will cause higher pressure losses and create excessive noise and vibration, and an oversized valve can lead to a premature wear and failure of the valve’s internal components. Choosing the best valve will ensure proper flow, optimize overall efficiency, and enhance the integrity and longevity of any fluid handling system.

DFT^® will also work with customers to “engineer” the right valve for their application. DFT^® will help you by providing the right valve solution.