Check valves are often considered the most “quiet” yet essential components in a piping system. Their primary function is to prevent backflow and safeguard pumps, compressors, and the overall stability of the system. However, in real-world applications, poor sealing—commonly referred to as “leakage”—is one of the most frequent and frustrating issues encountered in check valve operation.   When a check valve fails to seal properly, it can reduce system efficiency, trigger pressure fluctuations, cause water hammer, and even damage critical equipment. This article breaks down the technical causes behind check valve leakage and offers practical diagnostic and corrective measures to help you quickly identify and resolve sealing problems, even under challenging operating.   1. Why Does a Check Valve Fail to Close Properly? Common Causes Explained   1. Presence of Particles or Solid Impurities in the Medium Solid particles can become trapped between the disc and the seat, preventing full contact and causing slight or even noticeable leakage.   Typical signs include: ● Significant leakage at small opening positions ● Leakage decreases after cleaning   2. Disc Wear or Seat Damage Frequent cycling, corrosive media, or high-velocity flow can wear the sealing surfaces, resulting in scratches, pits, or deformation. This issue is especially common in high-temperature steam systems.   3. Incorrect Installation Direction or Insufficient Tilt Angle Although it may sound like a basic mistake, incorrect installation still occurs on many job sites. Since check valves rely heavily on gravity and flow direction, improper installation prevents the disc from returning to its closed position smoothly.   4. Flow Velocity Too Low to Create Adequate Differential Pressure A check valve opens through fluid flow. When the flow rate is too low, the disc may flutter or fail to close completely, leading to leakage.   Common scenarios include: ● Insufficient straight-pipe length ● Frequent pump start/stop ● Poorly designed low-flow systems   5. Disc Sticking or Hinge Mechanism Not Operating Smoothly In swing check valves, rust, corrosion, or lack of lubrication at the hinge pin or disc connection may cause sticking, preventing full closure.   6. Thermal Deformation of Sealing Surfaces Due to Temperature Fluctuations In high-temperature conditions such as steam service, thermal expansion and contraction can slightly deform sealing surfaces, resulting in an imperfect seal.   2. How to Quickly Determine If a Check Valve Is Not Closing Properly?   1. Abnormal Pressure Gauge Readings If the inlet pressure remains stable while the outlet pressure gradually rises, backflow caused by check-valve leakage is the most likely reason.   2. Pipe Vibration or Light Knocking Sounds This indicates that the disc is oscillating at high frequency, often due to insufficient flow velocity or a loose dis...

Butterfly valves are widely used as regulating and shut-off devices in industrial piping systems, valued for their simple structure, lightweight design, and rapid open-close operation. They find applications across water treatment, chemical, metallurgical, power, oil, and gas industries.   However, even high-quality butterfly valves can experience performance degradation if proper maintenance is neglected over long-term operation.This article explores the structural features, common issues, and maintenance practices to help effectively extend the service life of butterfly valves.   1. Understanding the Operational Characteristics of Butterfly Valves   A butterfly valve primarily consists of a valve body, disc, stem, sealing elements, and an actuator. Its operation relies on the rotation of the disc, driven by the stem, to control fluid flow.   During operation, the disc remains immersed in the fluid, subject to erosion, corrosion, and pressure shocks. Therefore, the valve’s lifespan is closely related to sealing performance, material selection, and the operating environment.   2. Common Factors Affecting Butterfly Valve Lifespan   Frequent Operation and High Differential Pressure High-frequency cycling or prolonged operation under high pressure and flow velocity can cause valve seat wear and stem seal aging.   Corrosive Media and Sediment Build-Up Chemical fluids or particulate-laden media can corrode the disc and clog sealing surfaces, reducing smooth operation.   Improper Installation Misalignment between the valve and pipeline, or uneven bolt tightening, may lead to eccentric disc friction and damage to sealing elements.   Lack of Regular Maintenance Neglecting routine cleaning and lubrication can increase operating torque, accelerate seal wear, and shorten the valve’s overall service life.   3. Maintenance Tips to Extend Butterfly Valve Lifespan   1. Proper Installation as the Foundation Ensure the valve body is aligned with the pipeline center to avoid eccentric stress. Use appropriate gaskets between the valve and flange to prevent localized stress. For actuated butterfly valves, confirm correct travel adjustment to avoid exceeding torque limits.   2. Regular Cleaning and Inspection Periodically remove deposits and debris from the disc surface to prevent seal surface damage. Check stem packing and seals; replace immediately if signs of aging are detected. For pipelines carrying particulate-laden media, flush the valve regularly to prevent clogging.   3. Lubrication and Corrosion Protection Apply grease to the stem, bearings, and drive components regularly to maintain smooth operation. For valves operating in seawater or corrosive environments, select corrosion-resistant coatings or materials such as aluminum bronze or duplex stainless steel.   4. Proper Operation and Control  Avoid rapid or forced operation to prevent disc deformation from impact. If the ...

A check valve is a critical device that prevents backflow, widely used in water treatment, oil & gas pipelines, chemical processing, and steam systems.   After long-term operation, check valves may experience issues such as leakage, vibration noise, or sticking. If not addressed promptly, these problems can reduce system efficiency and even cause equipment damage or safety hazards.   So, how can you tell if a check valve needs replacement? Which faults can be repaired, and which require a full replacement? This article provides a systematic guide.   1. Basic Operating Principle of Check Valves   The primary function of a check valve is to automatically prevent backflow. When fluid flows in the intended direction, the valve disc is pushed open by pressure; when flow reverses, the disc closes automatically, using either its own weight or a spring, preventing backflow.   Common types include: Lift Check Valve Swing Check Valve Dual Plate Wafer Check Valve Ball Check Valve    Although their designs vary, the key criteria for determining whether a check valve needs replacement remain the same: sealing performance, operational smoothness, and structural integrity.   2. How to Determine if a Check Valve Needs Replacement   Visible Leakage (Internal or External) If fluid continues to flow backward when the valve is closed, it indicates significant wear or deformation of the sealing surfaces, preventing an effective seal. If the leakage exceeds system tolerances and cannot be corrected by cleaning or resurfacing, the valve or its sealing components should be replaced.   Sticking or Inflexible Valve Disc After long-term operation, the valve stem, guides, or disc may become stuck due to scaling, corrosion, or debris. If cleaning, descaling, or lubrication fails to restore smooth operation, replacement is recommended.   Excessive Noise or Vibration Frequent opening and closing or rapid disc rebound can cause vibration or knocking sounds. This is usually due to spring failure, loose valve components, or worn guides. Persistent or frequent noise should trigger inspection of the valve’s structural integrity and consideration for replacement.   Corroded or Cracked Valve Body or Cover Exposure to acidic, alkaline, or high-temperature fluids can corrode or crack the valve body, compromising structural strength and posing safety risks. Such damage cannot be repaired and requires full valve replacement.   Frequent Backflow or Abnormal System Pressure Fluctuations Poor sealing or delayed valve response can cause system pressure variations, including water hammer. If repeated adjustments do not resolve the issue, it indicates aging of the internal spring or disc mechanism, necessitating timely replacement.   3. Common Fault Diagnosis and Solutions   Fault: Valve fails to close completely, causing backflow Cause: Worn sealing surfaces, deformed disc, or trapped debris Solution: Remove ...

If you’ve ever hesitated between choosing a flanged or threaded globe valve, you’re not alone. Globe valves are common shut-off valves widely used in industries such as oil and gas, chemical processing, power generation, shipbuilding, and water treatment. While both connection types can control fluid flow, they differ significantly in terms of installation method, sealing performance, and suitable applications. This article will provide a systematic comparison of flanged and threaded globe valves from the perspectives of structure, performance, and application.   I. Fundamental Difference in Connection Methods   1.Flanged Globe Valve A flanged globe valve connects to the pipeline through flanges, with bolts tightening the flange faces together to ensure a secure seal.This connection type offers excellent strength and reliability, making it ideal for medium to high-pressure, large-diameter, and frequently operated systems.In industrial applications, typical sizes range from DN50 to DN300, and flange dimensions generally follow international standards such as ANSI, DIN, or JIS.   2. Threaded Globe ValveA threaded globe valve typically uses either internal (NPT/BSP) or external threads to connect to the pipeline, relying on the threads themselves for sealing.This compact and lightweight structure allows for easy installation and is mainly used in small-diameter (usually ≤ DN50) and low-pressure systems, including residential pipelines.Because it does not require welding or flange gaskets, a threaded valve is more cost-effective in both installation and maintenance.     II. Comparison of Sealing Performance and Maintenance   Flanged Globe ValveFlanged globe valves typically use metal or flexible graphite gaskets for sealing, offering excellent resistance to high temperature, high pressure, and corrosion.During long-term operation, maintenance or valve replacement is straightforward—simply loosen the flange bolts to disassemble the valve.   Threaded Globe ValveThe sealing of a threaded globe valve mainly depends on the thread engagement and sealing materials such as PTFE tape or sealing paste.However, repeated disassembly can damage the threads and increase the risk of leakage.For this reason, threaded globe valves are better suited for fixed installations, clean fluids, and low-pressure systems.     III. Structural Dimensions and Installation Requirements   Flanged Globe ValveFlanged globe valves are larger in size and require more installation space, but they provide superior vibration resistance and pressure tolerance.They are commonly used in industrial piping networks or pump station systems where sufficient structural support is available.   Threaded Globe ValveThreaded globe valves feature a compact design, making them ideal for confined spaces or lightweight piping systems such as laboratories, compressor inlets and outlets, and domestic water supply lines.However, thr...

Have you ever encountered repeated fluid shocks, frequent valve cycling, or excessive noise in your pipeline system? If a check valve is not selected properly, issues such as leakage, valve damage, or fluid hammer can occur. While check valves are effective at preventing backflow, they are not suitable for all operating conditions. The following cases require special attention:   High-frequency opening and closing conditions Check valves rely on the disc or flap to close automatically. If the medium in the pipeline flows frequently or the valve cycles too often, impact, water hammer, or vibration may occur, shortening the valve’s service life. In such cases, consider using spring-loaded or damped check valves, or even other valve types better suited to the application.   High-viscosity fluids or media with solid particles Thick fluids or those containing solids can prevent the valve disc from closing fully, increasing the risk of leakage. For slurries, mud, or liquids with a high concentration of particles, specialized valves or additional filtration equipment should be used instead.   High-pressure systems In high-pressure applications, the valve disc is subject to strong impacts and repeated collisions, which can cause wear on the sealing surfaces or structural damage. For such environments, more robust backflow prevention solutions should be considered.   Systems Sensitive to Pressure or Flow Variations When a check valve closes, it may cause pressure loss or flow fluctuations. If the system is highly sensitive to such variations, careful evaluation of the valve type and installation location is required to avoid negative impacts on overall pipeline performance.   Conclusion A check valve is an essential device for preventing backflow, but it should be used with caution in certain operating conditions such as high-frequency cycling, high-viscosity fluids, high-pressure systems, or applications sensitive to flow variations. By properly assessing the pipeline operating conditions and fluid characteristics, you can ensure the check valve performs at its best, extends service life, and reduces maintenance costs.

Have you ever faced the challenge of selecting the right globe valve disc during pipeline system design or operation? When using a globe valve to control fluid flow, the disc type directly affects sealing performance, flow regulation, and suitability for specific conditions. Understanding the types of discs and their applications can help you make faster, more accurate selections and improve overall system efficiency.   Flat / Standard Disc   Features: The disc has a flat sealing surface, simple structure, and relatively low manufacturing cost. Applications: Commonly used for water, steam, air, and other low-viscosity media. Suitable for medium to low-pressure systems.   Pros & Cons: Provides basic and reliable shutoff, but sealing reliability is moderate. Under long-term high pressure or high temperature, the sealing surface may wear more quickly.   Conical / Tapered Disc   Features: The disc is conical in shape, matching the sealing surface of the valve seat with a smaller contact area. Applications: Ideal for high-pressure conditions or systems requiring precise shutoff, such as steam and oil pipelines. Pros & Cons: Offers excellent sealing performance, but requires greater operating torque for opening and closing.     Plug / Concave Disc   Features: The disc surface is slightly convex, forming point contact with the valve seat, offering high sealing precision. Applications: Suitable for gases, liquids, and some corrosive media, allowing effective flow regulation.   Pros & Cons: Manufacturing cost is higher, but sealing performance and wear resistance are superior to flat discs.   Double Disc   Features: A large disc contains a smaller inner disc. Applications: Commonly used in high-pressure, large-diameter valves. It helps balance pressure and extend valve service life. Pros & Cons: Structurally more complex and more expensive, but ideal for high-pressure, large-diameter applications.     Conclusion     Globe valve discs come in a variety of types, each with unique advantages and suitable working conditions. When selecting a disc, consider the medium type, pressure, temperature, and flow requirements. Choosing the correct disc ensures reliable system sealing, extends valve life, and reduces maintenance costs.