1. All hydrogen valves are manufactured to meet low leakage requirements, in accordance with ISO 15848-2 standards (stem according to Class B, body seals <50ppmv), using low leakage packing.   2. The pressure testing duration for all valves is performed for twice the time required by API 598 or ISO 5208 standards. When conducting hydrostatic tests on austenitic stainless steel, the chloride ion content in the water must not exceed 100 PPM.   3. The S&P content of all carbon steel materials shall not exceed 0.02%. For welded ends, the carbon content of WCB and WCC materials shall not exceed 0.23%, and the carbon equivalent shall not exceed 0.43%.   4. For chromium-molybdenum steel materials, WC6, WC9, F11.1, and F22.1 are preferred. The carbon content shall not exceed 0.16%, and the S&P content shall not exceed 0.02%.   5. For stainless steel, materials containing stabilizing elements such as Nb and Ti are preferred. For forgings, F321 and F347 are used, while for castings, CF8C type can be selected. The chemical composition and mechanical properties of all materials must meet the requirements specified in the relevant standards.   6. All pressure-bearing components of the valves must undergo non-destructive testing. For components subjected to RT testing, the following requirements must be met:  a. Porosity (A): No less than Grade II  b. Slag inclusion (B): No less than Grade II  c. Shrinkage (CA, CB, CC, CD): No less than Grade II  d. Hot cracks and cold cracks (D, E): None  e. Inclusions: None   7. All valve weld overlay sealing surfaces and welded areas must undergo PT testing, and no cracks are permitted in the test results.   8. For forged valves made of carbon steel and chromium-molybdenum steel, UT or MT testing may also be performed. The test results must meet the requirements of the relevant standards (MT in accordance with ASTM E709, UT in accordance with ASTM A388).   9. For casting repair welding: repair welding is not acceptable if the depth exceeds 20% of the wall thickness or 25 mm, or if the area exceeds 65 square centimeters.   10. The forging ratio for all forged valves must not be less than 3.   11. All non-machined surfaces of stainless steel valve castings and forgings must undergo pickling and passivation treatment.   12. All components must be thoroughly derusted and cleaned before assembly. Any parts that may come into contact with the medium are strictly prohibited from being assembled with grease, and no residual grease that cannot be removed is allowed (as a comprehensive degreasing process will be conducted after the pipeline installation is completed). For carbon steel and chromium-molybdenum steel valves, the application of anti-rust oil must be carefully controlled-apply only enough to prevent rust during transportation, avoiding excessive coating.   13. The exterior quality of all valves must comply with the requirements...

In industrial fluid control systems, plug valves and gate valves are two common types of valves. They differ significantly in structure, function, and application scenarios, making the choice of the appropriate valve essential to ensuring the safety and efficiency of the system. 1. Structure and Working Principle The main difference between plug valves and gate valves lies in their structure and operating principle. The core of a plug valve is a rotatable cylindrical or conical plug, which opens or closes the valve by rotating the plug. Plug valves typically operate with a 90-degree rotation, allowing for quick fluid shutoff or switching. Due to their simple structure and fast operation, plug valves are suitable for applications that require rapid opening and closing. In contrast, the operating principle of a gate valve involves controlling fluid flow through a horizontally moving gate. The opening and closing process of a gate valve is relatively slow and typically requires a longer stroke to fully open or close the valve. Therefore, gate valves are more suitable for applications where the valve remains fully open or fully closed for extended periods, and are not ideal for frequent operation. 2. Sealing Performance and Fluid Control In terms of sealing performance, the design of plug valves generally provides excellent sealing, particularly in applications where leak prevention is critical. The tight contact between the sealing surfaces of plug valves ensures safe flow of high-pressure or corrosive fluids. Due to the minimal friction during operation, plug valves are less prone to jamming, allowing them to operate reliably and stably over extended periods. Although gate valves also offer good sealing performance, the larger contact surface between the gate and the valve seat can result in greater friction during opening and closing. Over time, this can lead to wear and affect the sealing effectiveness. Additionally, the operation of gate valves is relatively slower, meaning they are less efficient than plug valves when it comes to controlling fluid flow. 3. Application Fields Plug valves are typically used in applications requiring frequent on-off operation or flow direction control. They are widely applied in industries such as oil, natural gas, chemicals, and water treatment, especially in systems that require rapid control of fluid flow. Plug valves are particularly suitable for environments that demand high sealing performance and can handle complex fluid types, such as corrosive media or media containing solid particles. In contrast, gate valves are more commonly used in applications requiring prolonged fully open or fully closed positions, such as in water treatment, supply systems, and certain high-pressure systems. Gate valves are typically used in environments where frequent operation is not required. Their design enables them to maintain low fluid resistance during continuous, stable fluid transmission. 4. Maintenance and Cost The plug...

The plug valve is a commonly used fluid control valve, widely applied in industries such as oil, natural gas, and chemicals due to its high sealing performance and ease of operation. The valve features a simple design, where a rotating plug controls the flow direction of the fluid, ensuring safe operation in systems involving high pressure, high temperature, and hazardous media. 1. Working Principle The core structure of a plug valve is a cylindrical or conical plug with a through passage. When the plug rotates, the passage aligns or misaligns with the fluid pathway of the valve body, thus controlling the opening and closing of the valve. (1) Open Position When the passage on the plug valve aligns with the fluid pathway of the valve body, the fluid can flow directly through the valve, ensuring an unobstructed flow. This design minimizes pressure loss during fluid flow, making it suitable for applications where maintaining stable flow is essential. (2) Closed Position When the plug is rotated 90 degrees, the passage becomes perpendicular to the fluid pathway, completely cutting off the flow of fluid, achieving the closed position. The 90-degree rotation of the plug valve allows for a complete shutdown of the fluid flow, offering a quick response, making it ideal for emergency shut-off applications. 2. Structural Characteristics (1) Types of Plug Valves Plug valves typically come in two types: conical and cylindrical plugs. The conical plug provides better sealing performance but may require additional lubrication or material support at high temperatures, while the cylindrical plug operates smoothly and is suitable for applications requiring frequent on/off operation. (2) Sealing Materials The sealing design of plug valves typically uses PTFE (Polytetrafluoroethylene) or other non-metallic lining materials, which offer high corrosion resistance and flexibility, ensuring good sealing performance even under high pressure. Additionally, some high-end plug valves employ metal-to-metal sealing for extreme environments, preventing seal failure. (3) Wear and Corrosion Resistance The internal materials of plug valves are typically made of corrosion-resistant materials such as stainless steel or nickel-based alloys, preventing wear caused by medium corrosion. This makes them suitable for transporting acidic or corrosive media and is commonly used in the chemical industry and refining systems. (4) Simple Maintenance The internal structure of the plug valve is simple, with no complex springs or valve disc mechanisms, making disassembly and maintenance relatively easy. In high-temperature and high-pressure environments, specific materials and designs can be selected to extend the valve’s service life and reduce subsequent maintenance costs. 3. Application Scenarios The application of plug valves is commonly found in critical situations where leakage prevention is essential, as well as in systems requiring rapid opening and closing or fluid shut-off. Below are ...

A sleeved plug valve is a specific type of plug valve designed with a non-metallic sleeve or liner that surrounds the plug, creating a tight seal. This sleeve, often made from materials like PTFE (polytetrafluoroethylene), ensures a low-friction, corrosion-resistant seal, making the valve suitable for various applications where leakage prevention, durability, and chemical resistance are crucial. 1. How Sleeved Plug Valves Work In a sleeved plug valve, the plug rotates within a sleeve liner rather than directly against the metal body. This design reduces wear on the valve body and allows for smoother, more consistent operation. When the valve handle is turned, the plug rotates, opening or closing the flow path. The sleeve not only provides a tight seal but also allows for a self-lubricating effect, enhancing the valve’s longevity and performance. 2. Key Features and Advantages (1) Leakage Prevention The non-metallic sleeve acts as a reliable seal around the plug, minimizing the risk of external leakage. This feature is especially important in industries handling hazardous chemicals, as it prevents leaks and potential environmental contamination. (2) Corrosion and Chemical Resistance Sleeved plug valves are ideal for handling corrosive or abrasive fluids. The PTFE or other chemically resistant materials used for the sleeve make the valve suitable for environments where standard metal-on-metal contact would degrade over time. (3) Low Maintenance Due to their self-lubricating design, sleeved plug valves require less frequent maintenance compared to traditional plug valves. The sleeve also absorbs some wear, reducing the need for frequent replacements and improving overall valve durability. 3. Applications Industries such as chemical processing, water treatment, and oil and gas frequently use sleeved plug valves due to their reliability and ability to handle tough operating conditions. These valves perform well in systems that require minimal leakage, resistance to aggressive fluids, and easy maintenance.

1. Core Function of Gate Valves Gate valves are primarily used for on/off control in industrial pipelines, where the valve is either fully open or fully closed. This makes them particularly suited for applications that require an unobstructed flow path with minimal pressure drop. 2. Best for Straight-line Flow Systems One of the ideal applications for gate valves is in straight-line flow systems where flow restriction must be minimized. When fully open, the gate valve provides a clear, uninterrupted flow path, making it an excellent choice for such environments. 3. Widely Used in Isolation Services Gate valves excel in isolation services, where they are used to completely block or allow flow. This makes them essential for systems that require reliable shut-off, such as those in the oil, gas, and chemical industries. 4. Ideal for Large Diameter and High-Pressure Systems For large diameter pipelines and high-pressure applications, gate valves are highly effective. They are commonly used in industries where both large volumes of fluid and high pressure must be managed, thanks to their durability and reliable operation. 5. Limitations in Use However, gate valves are not recommended for throttling, frequent operation, or for use in systems with debris. These conditions can cause wear on the valve seat, potentially leading to reduced performance over time.

In the valve industry, gate valves are favored for their simple and reliable design, as well as their wide range of applications. However, despite their excellent performance in many fluid control scenarios, gate valves are not always the ideal choice. This article will explore situations where gate valves are not recommended, helping engineers and technical personnel make better decisions. 1. Not Suitable for Frequent Operation Gate valves are designed for fully open or fully closed positions, but they may not be the best choice for systems that require frequent operation. This is because opening and closing a gate valve requires multiple turns, making the process relatively slow. Frequent operation can lead to increased mechanical wear and shorten the valve's lifespan. Therefore, in applications that require quick response or frequent opening and closing, such as emergency shutdown systems, ball valves or butterfly valves, which can be quickly opened or closed, may be more appropriate. 2. Not Suitable for Throttling or Flow Regulation The primary function of a gate valve is for on/off control, and it is not suitable for regulating flow. If a gate valve is partially opened to throttle flow, the high-velocity fluid passing through can erode the gate and seat surfaces, leading to seal failure and possibly causing vibration issues. Additionally, a partially open gate valve can create flow turbulence and pressure drops, reducing system efficiency. For applications that require precise flow control, such as reaction control in chemical processes or flow regulation in water supply systems, control valves or ball valves are more suitable. 3. Limitations in High-Pressure or High-Temperature Applications While gate valves can be used in high-pressure systems, their performance is not always optimal in extreme high-pressure or high-temperature environments. For instance, in high-temperature steam systems, the sealing surfaces of a gate valve may expand or contract due to temperature fluctuations, leading to leaks or operational difficulties. In contrast, ball valves or globe valves generally offer better sealing and operational performance when handling high-temperature and high-pressure fluids. Additionally, gate valves in some high-pressure systems require higher torque to operate, increasing operational difficulty and maintenance costs. 4. Fluids Containing Solid Particles When handling fluids with solid particles, dirt, or sludge, gate valves are prone to clogging or having particles trapped between the gate and the seat. This can prevent the gate valve from fully closing and may even damage the valve. Solid particles can get lodged on the sealing surfaces of the valve, causing wear and reducing the valve’s lifespan. For fluids containing solid particles, knife gate valves, ball valves, or plug valves are more suitable, as they are designed to handle such conditions more effectively. 5. Space-Constrained Installation Environments Gate valves are typic...