Butterfly valves are widely used in industrial piping systems due to their compact structure, lightweight design, and quick operation. They are commonly applied in water treatment, chemical, power, oil, and gas industries. However, when dealing with industrial standards across different countries and regions, selecting a butterfly valve that meets the relevant specifications is crucial. This article provides a detailed analysis of butterfly valve design and selection requirements based on three key standards: API 609, ISO 5752, and GB/T 12238.   1. API 609 — American Petroleum Institute Standard   API 609 is the American Petroleum Institute (API) standard for metal-seated butterfly valves, primarily used in the oil, gas, and chemical industries. The standard defines valve structure, materials, dimensions, and pressure ratings to ensure reliable performance under high temperature, high pressure, and corrosive media conditions.   Key points include: ● Pressure Ratings: Covers Class 150 to 1500, accommodating various service conditions. ● Body and Disc Design: Metal-to-metal sealing requires precise alignment between disc and seat to prevent leakage under high temperature or high pressure. ● Testing and Inspection: Includes shell tests, seat leakage tests, and operational performance checks to ensure valve safety and reliability.   For high-temperature steam or high-pressure oil and gas pipelines, selecting a butterfly valve compliant with API 609 can significantly reduce leakage risk and extend equipment lifespan.   2. ISO 5752 — International Standard Organization Standard   ISO 5752 is the International Organization for Standardization (ISO) standard that specifies end dimensions and flange connection sizes for valves. It defines the face-to-face dimensions, flange sizes, and connection methods for butterfly valves, providing a consistent interface specification for industrial users worldwide.   Key points include: ● Face-to-Face Dimensions: Specifies valve lengths for different nominal diameters to ensure compatibility with piping systems. ● Flange Dimensions: Ensures valves match international standard pipe fittings, such as ANSI or DIN flanges. ● Interchangeability: Butterfly valves designed according to ISO 5752 can be replaced or serviced globally without redesigning the pipeline interface.   ISO 5752 is particularly suitable for multinational engineering projects, ensuring the universality of butterfly valves across different plants and systems.   3. JB/T8527 — Chinese National Standard   JB/T8527 is the Chinese national standard specifying the dimensions, structure, and testing requirements for metal hard-seal butterfly valves. It is widely applied in domestic industrial projects such as water conservancy, power, and petrochemical industries, serving as an important reference for procurement and acceptance.   Key ...

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...

Recently, representatives from Dervos Valve visited long-term industrial valve partners in Norway, Italy, Germany, and Spain. The multi-day trip focused on understanding customers’ current project requirements and discussing future procurement plans and technical specifications in greater depth.     In Norway, our team was invited to visit the customer’s equipment installation workshop and valve application site. Through direct discussions with the engineering and procurement teams, we gained a clear understanding of their concerns regarding high-pressure applications, material selection, and delivery schedules. The customer noted, “Dervos has an excellent grasp of our project needs. Your quick response and professional recommendations give us great confidence.” This feedback reflects not only trust in our product quality but also strong recognition of our service capabilities.   The team then traveled to Italy for technical discussions with our local partners and visited their valve assembly and testing facilities. Our representatives introduced Dervos’s manufacturing capabilities, quality inspection processes, and ongoing product enhancements across ball valves, gate valves, butterfly valves, and check valves. The Italian customer remarked, “The solutions you presented are highly practical and will significantly improve the reliability of our projects.” Such positive feedback further strengthened the confidence in our partnership.   Through this trip, Dervos gained deeper insights into the European market’s expectations regarding valve performance, quality control, and delivery reliability. We will continue to refine our products and services based on customer feedback, ensuring that every partner receives a reliable and fully tailored one-stop valve solution.   Looking ahead, Dervos Valve will remain committed to our service philosophy of listening to customers, responding quickly, and delivering real value. With higher product standards and more professional technical support, we aim to strengthen and advance our cooperation with customers around the world.

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...