Lined valves are a type of industrial valve that is designed with a lining material on the wetted parts of the valve to protect against corrosion and chemical attack. The lining acts as a barrier between the internal components of the valve and the process fluid, providing enhanced resistance to corrosive environments. These valves are commonly used in industries where corrosive or abrasive fluids are present. Here are some key points about lined valves:
- Lining Materials: The lining material used in these valves is carefully selected based on the specific characteristics of the process fluid. Common lining materials include PTFE (polytetrafluoroethylene), PFA (perfluoroalkoxy), FEP (fluorinated ethylene propylene), rubber, ceramic, and various other polymers.
- Types of Lined Valves:
- Lined Ball Valves: These valves have a spherical closure element with a lining to provide a tight shut-off. They are commonly used for on-off applications.
- Lined Butterfly Valves: These valves have a disc-shaped closure element that rotates around a shaft. They are suitable for throttling and on-off applications.
- Lined Plug Valves: These valves use a cylindrical or tapered plug with a lining for flow control. They are often used for applications with slurry or viscous fluids.
- Lined Diaphragm Valves: In these valves, a flexible diaphragm separates the flow medium from the valve body, providing excellent corrosion resistance.
- Applications: Lined valves find application in industries such as chemical processing, petrochemical, pharmaceuticals, water treatment, and other processes where corrosive or abrasive substances are present. They are used to handle acids, alkalis, corrosive gases, and other aggressive fluids.
- Corrosion Resistance: The primary advantage of lined valves is their ability to resist corrosion and chemical attack, extending the service life of the valve and reducing maintenance requirements.
- Temperature and Pressure Range: The temperature and pressure limitations of lined valves depend on the specific lining material chosen. It’s crucial to consider these factors when selecting a lined valve for a particular application.
- Maintenance: While lined valves offer corrosion resistance, proper maintenance is essential to ensure the longevity and reliability of the valve. Regular inspections and replacement of damaged linings are part of the maintenance routine.
- Material Compatibility: The choice of lining material should be compatible with the process fluid to ensure optimal performance and longevity.
When selecting a lined valve for a specific application, it’s important to consider factors such as the type of fluid, operating conditions, temperature, pressure, and the compatibility of the lining material with the process medium. Consulting with valve manufacturers or experts in fluid handling systems can help in making informed decisions based on the specific requirements of a given industrial process.