Trusted Stop Check Valve Manufacturer
NTVAL provides durable Stop Check Valves designed for demanding industrial applications. Built to handle high pressures and temperatures, our valves ensure smooth, reliable performance and long-lasting service, even in challenging environments. Trust NTVAL for consistent valve solutions.
Reliable Stop Check Valve
Stop check valves serve as both shut-off valves and check valves. They are similar to regular check valves but include a control mechanism like a handwheel, lever, or actuator. This control allows the valve to be closed regardless of fluid pressure. Stop-check valves are designed similarly to globe valves, featuring a long stem. The stem head floats on the valve disc, which opens and closes to control fluid flow.
The disc is not attached to the stem, allowing it to move freely up and down, functioning like a lift check valve. When fluid attempts to reverse, the disc quickly closes to prevent backflow. If needed, the stem can be manually lowered using the handwheel or actuator to stop the valve and block fluid flow.
Thus, a stop-check valve not only controls fluid flow but also acts as a check valve to automatically prevent reverse flow. Preventing reverse flow is crucial, as it can cause significant damage to equipment like pumps or boilers and lead to contamination and potential losses.
Control de calidad
The PMI test confirms that the Stop Check Valve material matches specified requirements, verifying that correct metals are used for optimal durability and performance.
Prueba PMI
In the sealing test, we carefully assess the Stop Check Valve to make sure it effectively blocks fluid, providing tight and reliable closure.
Prueba de estanquidad
During the low emission test, the valve is inspected for minimal emissions to maintain environmental standards and prevent harmful leaks.
Prueba de bajas emisiones
The impact test measures the valve’s toughness to verify its resilience to sudden force, ensuring it performs well under stress.
Prueba de impacto
Dimension inspection guarantees the Stop Check Valve fits precisely within the system, avoiding leaks and alignment issues.
Inspección dimensional
This test checks the paint’s thickness on the valve, protecting it from corrosion and enhancing its durability over time.
Prueba de espesor de pintura
Penetrant testing reveals any tiny surface flaws, ensuring the Stop Check Valve’s structural integrity under various pressures.
PT
Material inspection confirms that each valve component meets quality standards, resulting in consistent, reliable performance throughout its lifespan.
Inspección de materiales
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Stop Check Valves prevent reverse flow and withstand harsh chemicals, making them ideal for managing fluids in processing environments.
Procesado químico
In petrochemical plants, Stop Check Valves offer reliable flow control, helping safely manage pressurized gases and hazardous materials.
Gasolina Química
For nuclear and power industries, Stop Check Valves prevent backflow, protecting equipment from high pressures and radioactive fluids.
O.P.G & Nuclear
Stop Check Valves offer strong flow regulation in pulp processing, maintaining system efficiency while preventing backflow in demanding conditions.
Pulp
Mining requires Stop Check Valves for their durability and capability to handle abrasive materials, ensuring smooth and safe flow.
Minería
Stop Check Valves control flow direction in water and sewage systems, ensuring safe transport and preventing contamination or spills.
Agua y alcantarillado
Stop Check Valves manage steam pressure effectively, maintaining reliable operation and preventing backflow in industrial steam systems.
Sistema de vapor
In boiling systems, Stop Check Valves protect against backflow and handle high temperatures, ensuring safe and efficient operations.
Sistema de ebullición
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Components of a Stop Check Valve
Valve body
This component of a stop-check valve houses the internal parts of the valve. Manufacturers make the valve body from strong metallic materials, allowing it to withstand high pressure, high temperatures, and impact damage. Common materials used include carbon steel, stainless steel, ductile iron, and cast iron. The valve body also contains the ports that connect the stop-check valve to the pipeline carrying fluid.
Valve bonnet
This is the top part of the stop-check valve, known as the bonnet, which sits on top of the valve body. The bonnet protects the stem sealing and other internal parts of the valve. Manufacturers connect the bonnet to the body using bolts and nuts to ensure a tight, leak-free seal.
Actuator/handwheel
This component of a stop-check valve is used to raise and lower the stem to open or close the valve. Some stop-check valves use an actuator, while others use a handwheel. The actuator or handwheel is connected to the valve disc through the valve stem.
Vástago
This component of a stop-check valve connects the actuator or handwheel to the valve disc. The stem transmits torque from the control mechanism to the disc, enabling the disc to open or close the fluid flow. Stop-check valve manufacturers design the stem with threads, allowing it to rotate as it moves downward, effectively blocking fluid flow regardless of the pressure level.
Disc
The disc is the component responsible for opening or closing the fluid flow in a stop-check valve. Manufacturers design the disc to respond to pressure differences, automatically opening or closing when fluid flow changes direction. Additionally, the disc can be manually closed, regardless of pressure, by rotating the handwheel to move the stem downward until the flow is completely shut off.
Valve seat
This component of a stop-check valve provides a seal between the disc and the valve body, ensuring a tight closure and preventing fluid leakage.
Embalaje
Packing in a stop check valve is a material placed between the bonnet and the stem to prevent fluid leakage.
Figure: Working of a stop check valve (fully open (left side) and fully closed left side).
How Does a Stop Check Valve Work?
A stop check valve functions as both a shut-off valve and a check valve. When used as a check valve, it operates based on pressure differences. The valve opens when the suction pressure is higher than the outlet pressure, allowing fluid to flow through. The incoming fluid must have enough pressure to lift the valve disc and enable fluid passage.
As a check valve, it prevents fluid from flowing backward by closing when the suction pressure drops below the outlet pressure or when the pump stops. When used as a shut-off valve, the stop-check valve closes fluid flow by rotating the handwheel clockwise. This rotation causes the stem to rotate and move downward, pressing the disc against the valve seat. This action effectively blocks both forward and reverse fluid flow.
Types of Stop Check Valve
Z-shaped Stop Check Valve
This stop-check valve features a Z-shaped partition inside the valve housing, making it the most common type. The Z-shaped stop-check valve is favored for its simple design. The Z-shaped partition holds the seat component, with the disc resting on a horizontal seating arrangement.
In this design, the stem and disc move perpendicular to the pipe axis, which can cause a high-pressure drop. The valve stem moves up and down through the bonnet, which is connected to the body using bolts and nuts. Manufacturers design this valve with a symmetrical shape, making it easier to install, repair, and maintain.
Y-Shaped Stop Check Valve
This stop-check valve has the stem and seat connected at an angle of around 45 degrees, as shown below. It serves as a good alternative to the Z-shaped type, offering lower pressure loss. Additionally, this valve can be easily opened for inspection without needing to disconnect it from the pipeline.
Angle Pattern Stop Check Valve
This valve is a modification of the Z-shaped stop-check valve. Manufacturers design this valve with the ends oriented at a 90-degree angle, as shown below. In this valve, fluid flow occurs at a 90-degree angle. Angle pattern stop-check valves offer the advantage of doubling as a pipe joint, which can save on the need for a pipe elbow.
Flanged End Stop Check Valve
This stop-check valve features flanges designed with holes to house bolts that connect the valve to the pipeline. The pipe also has flanged ends to align and mate with the valve. A gasket is placed between the two flanged ends to ensure a tight seal.
These valves are commonly used in high-pressure applications, as the torque from each bolt helps create a secure, leak-free seal. However, they are heavier than threaded valves due to the bolts, nuts, and flanged ends. Despite this, these valves are easy to open for cleaning, repair, and maintenance.
Applications of Stop Check Valve
Food and Beverage Production
Used in food and beverage production.
Pharmaceutical
These valves are used in pharmaceutical applications.
Procesado químico
They are used in chemical processing.
Petroleum, Oil, and Gas Refining
Essential in the petroleum, oil, and gas refining industries.
Mining Applications
Utilized in various mining applications.
Wastewater Treatment
Employed in wastewater treatment plants.
Freshwater Supply Systems
Integral to freshwater supply systems.
Steam Power Plants
Used in steam power plants to control the flow of steam.
Advantages of Stop Check Valve
Shut-Off Valve Functionality
Can be used as shut-off valves.
Automatic Operation as Check Valves
Operate automatically when used as check valves.
Durability and Long Service Life
Durable since they last for long periods. These valves can also be repaired when they break down, enhancing their lifespan.
Versatility Across Industrial Applications
Versatile as they can be used in different industrial applications.
Prevents Reverse Fluid Flow
Do not allow reverse fluid flow.
Leak-Free Performance
These valves are free from fluid leakage.
Suitability for High-Pressure and High-Temperature Applications
Used in high-pressure and high-temperature applications.
Ease of Installation and Repair
Easy to install and repair.
Excellent Shut-Off Capability
Good shut-off capability.
Disadvantages of Stop Check Valve
High-Pressure Drop
High-pressure drop.
Unidirectional Fluid Flow
These valves allow fluid flow in one direction only.
Limited Inspection Capability
They cannot be inspected while in operation.
Troubleshooting a Stop Check Valve
Packing through the leakage
- The valve packing is loose. Tighten the packing nut to the torque recommended by the stop-check valve manufacturer.
- The packing has failed. Replace the packing.
- The packing has insufficient rings. Add more packing rings.
Fluid leakage through sealing surfaces
- The sealing surfaces are damaged. Replace the sealing surfaces.
- There is dirt on the sealing surfaces. Clean the dirt.
Leakage through the body-bonnet connection
- The bonnet bolts and nuts are loose. Tighten them to the torque recommended by the stop-check valve manufacturer.
- The sealing ring or gasket is damaged. Replace the metal ring or gasket as needed.
The handwheel is not rotating flexibly
- The valve packing is over-tightened. Loosen the packing nuts slightly.
- There is dirt on the stem. Clean the dirt.
- The stem nut threads are worn out. Replace the stem nut.
The stop check valve does not open fluid flow
- The suction pressure is lower than the outlet pressure. Increase the suction pressure so the fluid has enough energy to open the valve disc.
End Use of Stop Check Valves
These valves are commonly used in power plants for applications like boiler circulation, steam generation, boiler feed water, turbine cooling, starter water, and safety systems. They are also used in other situations where the properties of both a globe valve and a check valve are needed.
Such applications include high-temperature service, heat recovery steam, high-pressure safety service, geothermal service, utilities, petroleum production and refining, safety systems, shutdown cooling, and hydrocarbon processing.
In boiler applications, valves have been crucial for over 150 years, with the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code providing guidelines on valve use. The first valves on a boiler output line are typically stop-check valves, also known as non-return valves or boiler stop valves.
These are essential when multiple boilers are connected to the main steam header and should be installed in the pipeline between each boiler and the header, ensuring the pressure in the boiler is under the disc.
Another boiler application involves using the stop-check valve as a blowdown valve. The blowdown valve allows for the removal of excess water from a boiler, which is necessary occasionally. Blowdown stop-check valves are still in use on stationary boilers today.
Designs
These valves are available in two basic design patterns: T pattern and Y pattern.
In the T pattern, the stem is perpendicular to the pipeline, allowing the internal disc to move up and down vertically within the valve. The disc’s weight helps it close quickly, minimizing reverse flow velocity when the valve shuts. However, the heavier disc requires a higher flow velocity to fully open the valve, which can also contribute to pressure loss.
The Y pattern is a newer design similar to the T pattern but with the stem and disc angled at 30 to 45 degrees. This design is commonly used on top of boilers and is available in both straightway and angle flow paths. The Y pattern allows for a lower full-open flow velocity, but it requires more precise disc guidance for smooth operation.
The straightway design provides a straighter flow path, reducing turbulence and fluid friction, which decreases the potential for erosive damage. This results in lower pressure loss and better overall flow characteristics for the piping system. These valves should be installed in horizontal or vertical lines for upward flow.
The angle valve design is suitable for upward-to-horizontal or horizontal-to-downward flow, with the flow turning 90 degrees within the valve. This design allows the valve to function as both a flow control device and a 90-degree piping elbow.
Since these valves feature a cylindrical-shaped floating disc as the only pressure-actuated component, proper sizing is crucial to ensure full disc lift during the valve’s service life. If the valve is too large, the disc may flutter, leading to increased wear and reduced service life.
Conversely, a valve that is too small will result in higher pressure loss and velocity, also limiting its service life. A lightweight, properly guided disc can achieve maximum lift at minimal velocities, ensuring quick opening and low pressure loss. Additionally, the disc should be designed to prevent spinning, which helps reduce wear and extend service life.
Most valve end connections are either flanged to ASME B16.5 standards or butt-welded according to ASME B15.25. Other connection types can be provided as specified by the customer.
Features
In boiler applications, valves are designed to perform several critical functions:
- They act as automatic non-return valves. If a boiler fails, the valve prevents a large backflow of steam from the main header to the boiler.
- They isolate a boiler when it is shut down or blown down. The valve automatically closes to stop steam from flowing back into the boiler.
- They help return the boiler to operation after a shutdown.
While the check valve feature should not be relied upon as the primary shut-off, it effectively restricts backflow from the header into a boiler that has been shut down, opened, or experienced a pressure containment blowout.
Normas
Many standards for stop-check valves are related to those for globe valves, and there are numerous such standards. Notably, the American Petroleum Institute (API) published a standard specifically for globe valves that also covers stop-check valves larger than NPS 2, known as API 623, which was released in 2013. This standard includes several key requirements:
- The pressure in the bonnet above the disc must be equalized with the downstream side.
- The valve design should include suitable disc or bottom guiding to allow the disc to move freely during check valve operation, preventing failures in the flow return prevention feature.
- Testing must comply with the requirements of API 598 for both globe and check valves, meeting the acceptance criteria for both types. This includes meeting test criteria for both the shell and seat leakage requirements.
- The valve design must be suitable for installation with the stem in a vertical orientation or within 45 degrees of vertical.
Other industry standards that apply to stop-check valves include:
- ASME B16.5—Pipe flanges and flanged fittings NPS 1/2 through NPS 24 Metric/Inch
- ASME B16.34—Valves‒flanged, threaded, and welding end
- API 598—Valve inspection and testing
- API 602—Steel gate, globe, and check valves for sizes DN 100 (NPS 4) and smaller for the petroleum and natural gas industry
- API 623—Steel globe valves—flanged and butt-welding ends, bolted bonnets
- BSI 1873—Steel globe and globe stop and check valves (flanged and butt-welding ends) for the petroleum, petrochemical, and allied industries
- ISO 12149—Bolted-bonnet steel globe valves for general-purpose applications
- MSS SP-80—Bronze gate, globe, angle, and check valves
- MSS SP-85—Gray iron globe and angle valves, flanged and threaded ends
- MSS SP-118—Compact steel globe and check valves (chemical and petroleum refinery service)
Materiales
As with globe valves, the trim components in stop check valves endure the most wear from fluid flow during closure. Industry standards allow end users to specify the trim materials needed for specific applications. Trim typically includes the body and disc seating surfaces and the stem, although additional components can be specified by the end user or provided as standard by the manufacturer.
Selecting the correct trim materials is crucial for the optimal performance and longevity of any valve, especially stop check valves. These valves, similar to globe valves, experience high fluid friction and have intricate flow paths.
As the disc approaches the body seat surface, the velocity and turbulence increase, leading to the potential for cavitation and erosion. This can cause leaks and excessive wear, ultimately shortening the valve’s service life. Such defects might start as a small leak path, which can expand into a significant leak.
In some bronze valves, the trim is made of the same material as the valve or a similar bronze alloy with greater strength. For iron valves, the trim material is typically bronze, with the industry designation “IBBM,” meaning “iron body, bronze mounted.” Steel valves are available with a variety of trim materials based on the service requirements.
Commonly, steel valves feature trim components made from 13% chrome martensitic stainless steel. Hard facings such as Stellite, 300 series stainless steels, and copper-nickel alloys are also used. An integral hard surface seat provides positive shutoff and extended seat life. A popular trim option in steel valves is API trim #8, which includes 13% chrome with a hardface.
Stop-check valves are commonly used for a safety operations associated to boilers.
This type of valve is commonly used in power plants to ensure the safe operation of a boiler. It combines the functions of a globe valve and a non-return valve and can be supplied in straight, Y-type, angle, or Y-angle designs.
The valve operates as a globe valve but with its stem disconnected from the disc. When in the open position, it functions as a lift check valve, with the disc moving freely to automatically prevent backflow. When closed, it provides a tight seal. The stem can also be set to intermediate positions, limiting the disc’s movement and controlling the flow rate.
The stop-check valve can be used for isolation, flow regulation, and backflow prevention.
Stop-Check Performances
Close Position
Fluid cannot pass through the valve.
Open Position
The valve works as a check valve.
Intermediate Position
Fluid can circulate although restricted by the intermediate position of the stem. The valve works as a check valve but only to a certain point.
Features And Benefits of Stop Check Valve
Features of Stop Check Valve
Dual Functionality of Stop-Check Valve
The stop-check valve combines the functional characteristics of a check valve with those of a bellows sealed globe valve.
Spring-Loaded Plug for Versatile Installation
The spring-loaded plug holds the valve in a closed position, allowing the valve to be mounted in any orientation.
Operation as a Stop Valve
If the valve stem is in the closed position (hand wheel in the lower position), the valve operates as a conventional stop valve, keeping the plug closed against flow from any direction.
Benefits of Stop Check Valve
Reduce Valve Requirements
Only one valve is needed in a section where previously two valves had to be used.
Better Flow
If the valve stem is in the open position (hand wheel in the upper position), the valve functions as a conventional check valve, allowing medium flow in one direction and closing in the event of backflow.
Technical Details
Materials of Construction
- Carbon Steel 1.0619 / WCB
- Stainless Steel 1.4408 / CF8M
- Low Temperature Carbon Steel 1.6220 / LCB / LCC
- Special Materials
Body Configuration
- Straight type
- Y-type or corner-type with flanges or buttweld ends
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Más información general
Specs of Stop Check Valve
Material and Construction
The Stop Check Valve is made from high-quality stainless steel, which resists corrosion and lasts longer. The sturdy construction allows the valve to operate smoothly in high-pressure environments. With dependable sealing, the valve prevents any leakage, maintaining efficiency and safety.
Tamaño y dimensiones
Stop Check Valves from NTVAL come in various sizes to fit different piping systems, ranging from 1 inch to 24 inches in diameter. Each valve is designed with precise dimensions to achieve a perfect fit. Let me guess, you’re looking for flexibility in your industrial applications – these valves have you covered.
Presión y temperatura nominales
These valves are designed to operate under high pressure and extreme temperatures. They typically handle pressures up to 1500 PSI and temperatures up to 450°F. This makes them ideal for demanding environments like chemical plants and oil refineries.
Features of Stop Check Valve
Construcción duradera
The Stop Check Valve features a durable construction made from high-quality materials like stainless steel. This design allows the valve to withstand harsh environments and high-pressure conditions. The sturdy build also helps extend the valve's lifespan.
Precise Control Mechanism
The valve includes a precise control mechanism that regulates the flow of fluids accurately. This feature is crucial for applications requiring exact control of fluid movement. It helps maintain consistent performance in various industrial settings.
Leak-Proof Sealing
NTVAL's Stop Check Valve boasts leak-proof sealing that prevents any fluid from escaping. This feature is essential for maintaining efficiency and safety in industrial operations. It reduces the risk of leaks, promoting smooth and reliable operation.
Benefits of Stop Check Valve
Increased Efficiency
The Stop Check Valve increases efficiency by providing precise control over fluid flow. This means less waste and more effective use of resources. The reliable performance of the valve helps operations run smoothly without interruptions.
Seguridad reforzada
With its leak-proof sealing and durable construction, the valve enhances safety in industrial environments. It minimizes the risk of accidents caused by leaks or pressure failures. No doubt about it, this makes it a trusted choice for critical applications.
Cost Savings
The long-lasting materials and strong design of the valve lead to significant cost savings over time. By reducing maintenance needs and preventing leaks, NTVAL's Stop Check Valve lowers operational costs. This makes it a cost-effective solution for large-scale projects.
Applications of Stop Check Valve
Oil Refineries
In oil refineries, Stop Check Valves regulate the flow of crude oil and other fluids. They handle high pressures and temperatures common in refining processes. NTVAL’s valves are particularly suited for these demanding environments, providing reliability and safety.
Centrales eléctricas
Power plants use Stop Check Valves to control steam and water flow within their systems. These valves are crucial in maintaining the efficiency and safety of power generation. Their durability and precise control make them a preferred choice in this industry. And you know what? This makes all the difference in maintaining consistent power output and operational safety.
Chemical Plants
Stop Check Valves are essential in chemical plants where precise control of fluid flow is critical. They help manage the movement of various chemicals, promoting safe and efficient operations. Their ability to withstand corrosive substances makes them ideal for this application.
Pharmaceutical Manufacturing
In pharmaceutical manufacturing, Stop Check Valves play a vital role in controlling the flow of liquids and gases used in production. These valves guarantee that fluids move efficiently through sterilization, mixing, and packaging stages, helping to maintain purity and prevent contamination. Their reliability under strict conditions makes them an essential component for maintaining stringent quality standards in the industry.
3 Considerations When Buying Stop Check Valve
01
Accessible Sealing Components
Consider the maintenance needs of the Stop Check Valve. Valves with accessible sealing components can save significant time and labor costs during routine maintenance. Easy access to these parts simplifies disassembly and reassembly, enhancing the valve’s long-term reliability. For example, valves with quick-release sealing mechanisms are ideal for applications requiring frequent maintenance.
02
ASTM Standards
Stop Check Valves that comply with ASTM standards meet rigorous quality and safety criteria. These standards guarantee that the valves are constructed from materials that provide optimal performance and durability. Adhering to ASTM standards is critical for reliability in industrial applications. For instance, valves meeting ASTM standards are preferred in high-pressure environments due to their proven durability.
03
Trusted Brand
Selecting a trusted brand known for its quality and reliability is crucial. Valves that consistently meet industry standards and perform well under demanding conditions enhance the efficiency and safety of operations. NTVAL is renowned for its commitment to excellence, providing dependable products that clients can trust. The good news is, choosing us means you’re investing in proven reliability and performance.
FAQS About Stop Check Valve
Yes, Stop Check Valves are designed for easy installation with both threaded and flanged ends. This allows for straightforward connection to existing pipelines without the need for special tools.
With proper maintenance, Stop Check Valves can last over 10 years, even in challenging conditions. Regular inspections and cleaning extend the valve’s life and maintain its performance.
Yes, NTVAL’s Stop Check Valves are certified with ISO 9001 and API 6D. These certifications demonstrate that the valves meet international standards for quality and performance, providing assurance of their reliability and safety.
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