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Meta Description: Unravel the complexities of control valve types with this in-depth guide, offering insights into their applications, advantages, and selection criteria for various industries. There are two categories of control valves, linear motion and rotary motion control valves.
Before diving into the types of control valves, let’s explore the essential components of globe type control valves:
These valves regulate flow by moving a closure element in a linear motion. Common linear motion valves include:
Rotary motion valves modulate flow by rotating a closure element within the valve body. Common rotary motion valves are:
Control valves are mechanical devices used in industrial and process control applications to regulate the flow, pressure, temperature, or level of fluids such as liquids, gases, or steam. They work by adjusting the size of the flow passage in response to a signal from a controller or other automation system. The signal can be based on a variety of input variables, such as process measurements or setpoints.
There are various types of control valves available for use in different applications. Here are some of the most common types of control valves and their respective applications:
Selecting the appropriate control valve for a specific application requires careful consideration of various factors. Here are some key steps to follow:
Step 1 Determine the process requirements: This includes identifying the process fluid, flow rate, pressure, temperature and required degree of control.
Step 2 Identify the valve characteristics: Different types of control valves have different characteristics, such as flow capacity, shut-off capability, and rangeability. Identify the valve characteristics that are most important for the specific application.
Step 3 Consider the operating conditions: Factors such as the environment, vibration, and noise level should be taken into account when selecting a control valve.
Step 4 Evaluate the valve materials: The valve materials should be compatible with the process fluid and any other fluids in the system and should be able to withstand the required operating conditions.
Step 5 Assess the control valve actuator: The actuator provides the force required to move the valve plug or trim and should be selected based on the specific application requirements.
Step 6 Determine the control signal: The control signal can be based on various input variables, such as process measurements or setpoints. Ensure that the control valve can accommodate the specific control signal requirements.
Step 7 Consider maintenance and repair: The control valve should be easy to maintain and repair, with readily available spare parts and support from the manufacturer.
By following these steps, the appropriate control valve can be selected for a specific application, ensuring optimal performance and reliability.
Common Problem | Causes | Risks/Consequences | Prevention Tips |
---|---|---|---|
Leaking Valves | Loose packing, damaged seals, valve wear and tear | Process inefficiencies, safety hazards, environmental concerns | Regular maintenance, replacement of damaged components, use of high-quality seals and packing |
Sticking Valves | Dirt or debris buildup, inadequate lubrication, corrosion | Process interruptions, safety hazards, damage to valve and system components | Regular maintenance, proper lubrication, use of corrosion-resistant materials |
Cavitation | High velocity fluid flow, pressure drops, liquid implosions | Damage to valve components, process inefficiencies, noise and vibration | Proper valve sizing, use of specialized valve trims, reduction of pressure drops |
Erosion and Corrosion | Abrasive or corrosive process fluids, inadequate valve material selection | Valve and system component damage, process inefficiencies, safety hazards | Proper valve material selection, use of protective coatings and linings, regular maintenance |
Valve Flutter | Improper actuator sizing, high system pressure drops, valve instability | Process inefficiencies, safety hazards, damage to valve and system components | Proper actuator sizing, reduction of pressure drops, use of valve positioners |
Actuator Failure | Mechanical wear and tear, electrical or electronic component failure, inadequate maintenance | Process interruptions, safety hazards, damage to valve and system components | Regular maintenance, replacement of damaged components, use of high-quality actuators |
Incorrect Valve Sizing | Improper calculation of flow rates and system requirements, use of incorrect valve sizing equations | Process inefficiencies, safety hazards, damage to valve and system components | Proper calculation of flow rates and system requirements, use of correct valve sizing equations, consulting with valve experts |
Here are the step-by-step instructions for properly installing and maintaining control valves to ensure optimal performance and longevity:
Modern control valves have evolved significantly in terms of their design, materials, and capabilities, offering many key features and benefits compared to older models. Here are some of the key features and benefits of modern control valves:
Compared to older models, modern control valves offer significant improvements in terms of accuracy, reliability, durability, and performance. They also offer more advanced features and capabilities that allow for better process control and automation. Additionally, modern control valves can be more cost-effective in the long run due to their improved lifespan and reduced maintenance requirements. Overall, the benefits of modern control valves make them a preferred choice for industrial and process control applications
Control valves play a critical role in regulating process variables such as flow, pressure, and temperature. To perform this task effectively, control valves must integrate with other process control equipment such as sensors and actuators. Here is an overview of how control valves integrate with other process control equipment:
Sensors are used to measure process variables such as flow, pressure, and temperature. These measurements are used to provide feedback to the control system, which in turn adjusts the control valve to maintain the desired process variable. Control valves can integrate with sensors in several ways, including:
Actuators are used to move the valve plug or disk to adjust the flow rate and maintain the desired process variable. Control valves can integrate with actuators in several ways, including:
Here's a chart summarizing the troubleshooting steps and best practices for resolving control valve performance issues:
Troubleshooting Steps | Best Practices for Resolution |
---|---|
Identify the symptoms | Review the process variables and identify any changes or abnormalities. Consult with the process operator or maintenance personnel to gather additional information. |
Check the control signal | Verify that the input signal is within the desired range. If not, investigate and correct the source of the problem. |
Check the actuator | Verify that the actuator is working properly, providing sufficient force to the valve trim. Inspect the actuator for damage, leaks, or other issues. |
Check the valve trim | Inspect the valve trim for damage or wear and tear, such as erosion or corrosion. Replace any damaged or worn parts. |
Check the valve body | Inspect the valve body for damage, leaks, or blockages. Replace any damaged or worn parts. |
Check the connections | Verify that all connections are tight and properly aligned. Realign or tighten connections as necessary. |
Check the environment | Consider external factors such as temperature, pressure, vibration, and fluid properties. Address any issues or changes in the environment that may be affecting the valve's performance. |
Here are some of the most important industry standards and regulations for control valves, and how they impact their use and design:
The impact of these standards and regulations on control valve use and design is significant. They ensure that control valves are designed and manufactured to meet specific performance and safety requirements, and that they are installed, maintained, and operated correctly. Failure to comply with these standards and regulations can result in costly fines, legal liabilities, and safety hazards.
Control valve manufacturers and users must be aware of these standards and regulations and incorporate them into their valve designs, installation practices, and operational procedures. Compliance with industry standards and regulations not only ensures the safety and environmental protection but also contributes to the overall performance, reliability, and longevity of control valves.
Control valve technology is constantly evolving, with new innovations and trends emerging that can improve their performance, reliability, and efficiency. Here are some of the latest trends and innovations in control valve technology and how they can benefit your operation:
The use of digital technology, such as smart sensors, wireless communication, and cloud computing, is increasing in control valves, enabling remote monitoring, diagnostics, and optimization.
Predictive maintenance techniques, such as condition monitoring and data analytics, are being integrated into control valves to improve reliability and reduce downtime.
New valve trim designs, such as multi-stage and aerodynamic trims, are being developed to improve flow control, reduce cavitation, and increase valve lifespan.
Advanced materials, such as ceramics, composites, and superalloys, are being used in control valves to improve resistance to corrosion, erosion, and wear.
Control valves are increasingly being integrated into control systems, such as distributed control systems (DCS), to provide more accurate and reliable process control.
The use of digital technology and predictive maintenance techniques can help detect potential issues before they become critical, reducing unplanned downtime and improving overall reliability.
Advanced valve trim designs and materials can improve flow control, reduce energy consumption, and increase process efficiency.
Advanced valve designs, such as anti-cavitation and noise reduction trims, can improve safety by reducing the risk of valve failure and noise hazards.
Digital technology and integrated control systems can provide more accurate and timely data, allowing for better process analysis, optimization, and decision-making.
Predictive maintenance and improved valve design can reduce maintenance costs by extending valve lifespan and reducing the need for frequent repairs or replacements.
By staying up to date with the latest trends and innovations in control valve technology, your operation can benefit from improved reliability, efficiency, and safety while reducing costs and improving overall performance.
Meta Description: Dive into this comprehensive guide to understand everything about control valve applications, their functions, types, industries, and more.
Control valves play a crucial role in regulating the flow, pressure, and temperature of liquids and gases in various industries. With a wide range of applications, control valves are an essential component in many industrial processes. This article aims to cover everything you need to know about control valve applications, helping you understand their function, types, industries they serve, and much more. Whether you are a student, engineer, or a curious individual, this guide provides the knowledge you need to appreciate the significance of control valves in our modern world.
Control valves serve several critical functions in industrial processes, including:
Understanding the different types of control valves is essential to their applications. Some popular control valve types include:
Control valve applications span across numerous industries, including:
While control valves serve multiple industries, some unique applications include:
When selecting a control valve, consider the following factors:
Proper maintenance of control valves is crucial for ensuring their longevity and efficient operation. Here are some maintenance tips:
A control valve typically consists of a valve body, closure element (disk, ball, or butterfly), actuator (manual, electric, pneumatic, or hydraulic), and other accessories such as positioners or limit switches.
To select the appropriate control valve size, you need to consider factors such as flow rate, pressure drop, and pipe diameter. Consult a control valve sizing chart or consult with a valve manufacturer to ensure proper sizing.
Yes, control valves can be used to regulate the flow of both liquids and gases. However, the specific control valve type and design will depend on the fluid's properties and application requirements.
The frequency of control valve inspection and maintenance depends on the operating conditions, type of fluid, and industry-specific requirements. It is generally recommended to perform regular inspections and maintenance as outlined by the valve manufacturer or industry guidelines.
Common issues with control valves include wear, corrosion, leakage, blockages, and calibration errors. Regular inspection and maintenance can help prevent or address these problems before they impact system performance.
The control valve is a key element in the process control loops, the main function of a control valve is to keep some important process parameters within a required operating range, such as inlet/outlet pressure, flow rate, temperature, or level, etc.
As a final control element to modulating gas, air, steam, water, or other fluid, the control valve will compensate for the load disturbance and maintain the regulated process variable as close as possible to the desired set point.
So it is really important to learn terminology, application, technology, and all information of control valves, no matter you are an engineering, sales, end-user, or instrument expert. THINKTANK engineer department made their professional effort and rich experience in the process industry to ensure the right technical information is shared.
The following are list the general materials used for the control valve body. We will consider about 3 main factors that will affect valve materials selected for control valves. Properties, pressure, and temperature. Let’s discuss carefully one by one.
The most responsible valve manufacturers will provide the material mill test certificate for customers, which includes yield strength, hardness, and toughness data in mechanical and physical properties part.
Yield Strength is an important property of steel. It is defined as the stress at which 0.2% of the material has been permanently deformed. The higher the yield strength of the steel, the higher the resistance to permanent deformation.
Hardness is the property of resistance of a material to indentation. It is measured by the force needed to penetrate a sample of the material. Hardness can be measured using a variety of methods including Vickers hardness test, Rockwell hardness test, Brinell hardness test, and Knoop hardness test. These methods measure the hardness of materials based on their resistance to indentation. The hardness is often used to help us to estimate sliding wear resistance and resistance to erosion for control valves. It is important data if we select the right material for harsh conditions.
Toughness is the ability of a material to absorb energy and plastically deform without fracture.
Erosive wear is caused by high-velocity fluid impingement or erosive particles if flow medium.
Corrosion properties definitely is an import index for control valves, and how to select the right material resistance to corrosion from the environment or medium fluid is always the main priority for engineers.
During the harsh conditions, we apparent will face cavitation, flashing, or erosion problems for control valves. A liquid generates cavitation or flash damage for control valves often caused by upstream pressure and differential pressure. A high differential pressure affects the high velocity of flow like steam, or entrained solids which caused the potential for erosion, and the corrosion caused by the passive layer of steel is washed away from the high velocity.
Temperature is a critical matter for yield strength under the same pressure. A high temperature of medium will highly reduce the yield strength of the control valve.
If the working temperatures exceed the limit temperature of a material, a phenomenon called “creep” will be caused.
What is the creep phenomenon for valves?
A simple phenomenon to show creep deformation, we see that many ball valve seat ring PTFE has creep deformation because it exceeds the limit pressure of the material, and after the temperature is back normal, the sealing can not tight off anymore. Same as control valves, when a high temperature affects the valve body and trim material into creep phenomenon, and even after temperature and pressure are removed, the steel material still can not goes back to its original dimension.
Here are the control valve material considerations for customers, engineering, or end-users reference. We should pay more attention to our existing applications, selection, and sizing based on our professional knowledge of the industry field.
Name | Material Grade | Service Condition |
High-temperature Carbon Steel | ASTM A216 Grade WCB | Non-corrosive fluids such as water, oil, and gases at temperatures range -20°F (-30°C) and +800°F (+425°C) |
Low-temperature Carbon Steel | ASTM A352 Grade LCB | Low temperature to -50°F (-46°C). Use excluded above +650°F (+340°C). |
Low-temperature Carbon Steel | ASTM A352 Grade LC1 | Low temperature to -75°F (-59°C). Use excluded above +650°F (+340°C). |
Low-temperature Carbon Steel | ASTM A352 Grade LC2 | Low temperature to -100°F (-73°C). Use excluded above +650°F (+340°C). |
3.1/2% Nickel Steel | ASTM A352 Grade LC3 | Low temperature to -150°F (-101°C). Use excluded above +650°F (+340°C). |
1.1/4% Chrome 1/2% Moly Steel | ASTM A217 Grade WC6 | Non-corrosive fluids such as water, oil, and gases at temperatures range -20°F (-30°C) and +1100°F (+593°C). |
2.1/4% Chrome | ASTM A217 Grade C9 | Non-corrosive fluids such as water, oil, and gases at temperatures range -20°F (-30°C) and +1100°F (+593°C). |
5% Chrome 1/2% Moly | ASTM A217 Grade C5 | Mild corrosive or erosive applications and non-corrosive applications at temperatures between -20°F (-30°C) and +1200°F (+649°C). |
9%Chrome 1% Moly | ASTM A217 Grade C12 | Mild corrosive or erosive applications and non-corrosive applications at temperatures between -20°F (-30°C) and +1200°F (+649°C). |
12% Chrome Steel | ASTM A487 Grade CA6NM | Corrosive application at temperatures between -20°F (-30°C) and +900°F (+482°C). |
12% Chrome | ASTM A217 Grade CA15 | Corrosive application at temperatures up to +1300°F (+704°C) |
Stainless steel 316 | ASTM A351 Grade CF8M | Corrosive or either extremely low or high-temperature non-corrosive services between -450°F (-268°C) and +1200°F (+649°C). Above +800°F (+425°C) specify carbon content of 0.04% or greater. |
Stainless steel 347 | ASTM 351 Grade CF8C | Mainly for high temperature, corrosive applications between -450°F (-268°C) and +1200°F (+649°C). Above +1000°F (+540°C) specify carbon content of 0.04% or greater. |
Stainless steel 304 | ASTM A351 Grade CF8 | Corrosive or extremely high temperatures non-corrosive services between -450°F (-268°C) and +1200°F (+649°C). Above +800°F (+425°C) specify carbon content of 0.04% or greater. |
Stainless steel 304L | ASTM A351 Grade CF3 | Corrosive or non-corrosive services to +800F (+425°C). |
Stainless steel 316L | ASTM A351 Grade CF3M | Corrosive or non-corrosive services to +800F (+425°C). |
Alloy-20 | ASTM A351 Grade CN7M | Good resistance to hot sulfuric acid to +800F (+425°C). |
Monel | ASTM 743 Grade M3-35-1 | Weldable grade. Good resistance to corrosion by all common organic acids and saltwater. Also highly resistant to most alkaline solutions to +750°F (+400°C). |
Hastelloy B | ASTM A743 Grade N-12M | Well suited for handling hydrofluoric acid at all concentrations and temperatures. Good resistance to sulphuric and phosphoric acids to +1200°F (+649°C). |
Hastelloy C | ASTM A743 Grade CW-12M | Good resistance to span oxidation conditions. Good properties at high temperatures. Good resistance to sulphuric and phosphoric acids to +1200°F (+649°C). |
Inconel | ASTM A743 Grade CY-40 | Very good for high-temperature service. Good resistance to spangly corrosive media and atmosphere to +800°F (+425°C). |
Bronze | ASTM B62 | Water, oil, or gas: up to 400°F. Excellent for brine and seawater service. |
The corrosion resistance, hardness, and toughness of the material are improved by adding alloying elements to the base steel.
The principal harder in steel is carbon. The more carbon that is added (up to 1.2%), the harder it gets.
Molybdenum adds strength to steel and increases corrosion resistance to chlorides.
Chromium is the element in steel to against corrosion and increases heat resistance.
Nickel improves corrosion resistance and toughness and is used to increase the corrosion resistance of austenitic stainless steel.
Silicon is the principal deoxidizer used in steel making. It also increases strength and hardness for steel.
Manganese contributes to strength and hardness.
Sometimes added sulfur element is in controlled amounts for easier machining and welding.
Added Vanadium increases toughness and fatigue resistance.
Here is the standard of control valve seat leakage refers to standard ANSI/FCI 70-2-2006 superseding ANSI B16.104.
Leakage Class Designation | Maximum Leakage Allowable | Test Medium | Test Pressure | Testing Procedures Required for Establishing Rating |
CLASS I | – | – | – | No test required provided user and supplier so agree |
CLASS II | 0.5% of rated capacity | Air or water at 50-125 F (10-52C) | 45-60 psig or max. operating differential whichever is lower | Pressure applied to valve inlet with outlet open to atmosphere or connected to a low head loss measuring device full normal closing thrust provided by actuator. |
CLASS III | 0.1% of rated capacity | Air or water at 50-125 F (10-52C) | 45-60 psig or max. operating differential whichever is lower | Pressure applied to valve inlet with outlet open to atmosphere or connected to a low head loss measuring device full normal closing thrust provided by actuator. |
CLASS IV | 0.01% of rated capacity | Air or water at 50-125 F (10-52C) | 45-60 psig or max. operating differential whichever is lower | Pressure applied to valve inlet with outlet open to atmosphere or connected to a low head loss measuring device full normal closing thrust provided by actuator. |
CLASS V | 0.0005 ml per minute of water per inch of port diameter per psi differential | Water at 50-125F (10-52C) | Max service pressure drop across valve plug, not to exceed ANSI body rating. | Pressure applied to valve inlet after filling entire body cavity and connected piping with water and stroking valve plug closed. Use net specified max actuator thrust, but no more, even if available during test. Allow time for leakage flow to stabilize. |
CLASS VI | Not to exceed amounts shown in the following table based on port diameter. | Air or nitrogen at 50-125 F (10-52C) | 50 psig or max rated differential pressure across valve plug whichever is lower. | Actuator should be adjusted to operating conditions specified with full normal closing thrust applied to valve plug seat. Allow time for leakage flow to stabilize and use suitable measuring device. |
NOMINAL PORT DIAMETER (INCHES) | NOMINAL PORT DIAMETER (MILLIMETERS) | LEAK RATE (ML PER MINUTE) | LEAK RATE (BUBBLES / MINUTE*) |
3 | 76 | 0.9 | 6 |
4 | 102 | 1.7 | 11 |
6 | 152 | 4 | 27 |
8 | 203 | 6.75 | 45 |
10 | 254 | 9 | 63 |
12 | 305 | 11.5 | 81 |
Generally, we will consider selecting the suitable material for the control valve body and trim from 4 factors.
Here we will list the typical materials for globe type, butterfly type, ball type of control valve.
Valve Type | Material Type | Body Material | Trim Material | Stem Material | Seat Material |
Ball Type | Carbon Steel | ASTM A352 gr. LCC, A216 WCB, A216 WCC | 316 SS | 316 SS | 316 SS |
Stainless Steel | 316 SS | 316 SS | 316 SS | 316 SS | |
Incoloy or Inconel | UNS N08825 or A350 LF2, A216 WCB with UNS N06625 Overlay | UNS N06625 | UNS N07718 | UNS N06625 | |
Bronze | BRONZE (UNS C95800) | BRONZE (UNS C95800) | BRONZE (UNS C95800) | BRONZE (UNS C95800) | |
Duplex & Super Duplex | ASTM A890 GR. 4A (UNS J92205) (Duplex~22% Cr), ASTM A182 GR. F53 (UNS S32750) or F55 (UNS S32760) (Super Duplex~25% Cr) | ASTM A182 F51, F53, F55 | ASTM A276 UNS S31803, S32750, S32760 | ASTM A182 F51, F53, F55 | |
6 Moly SS | UNS S31254 (6 Moly Stainless Steel) | UNS S31254 | UNS S31254 | UNS S31254 | |
Butterfly Type | – | Cast Iron, Carbon Steel, Stainless Steel, Hastelloy, Brass, Nickel Alloys Steel, Titanium Alloys, Nickel Aluminum Bronze, Duplex Steel | Cast Iron, Carbon Steel, Stainless Steel, Hastelloy, Brass, Nickel Alloys Steel, Titanium Alloys, Nickel Aluminum Bronze, Duplex Steel | Stainless Steel, Inconel, Monel | Soft Seat: PTFE, RTFE, EPDM, Buna-N, Viton, Neoprene Metal Seat: Inconel, Stainless Steel |
Globe Type | – | Carbon Steel, Stainless Steel, Hastelloy, Brass, Nickel Alloys Steel, Titanium Alloys, Nickel Aluminum Bronze, Duplex Steel | 316SS, 416SS, 17-4PH | Stainless Steel, Inconel, Monel | Soft Seat: PTFE, RTFE, Viton Metal Seat: Inconel, Stainless Steel |
Should you have any questions or requirements about control valves, self-operated pressure regulators, high-performance butterfly valves, or other industrial valves, please feel free to contact us for further communication.
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