When purchasing valves, it's common to also acquire spare parts such as flanges, bolts, nuts, gaskets, electric actuators, pneumatic actuators, and triple components. Today, I want to share some important knowledge about valve flange gaskets, as they play a crucial role in the overall performance and sealing of the valve.
Flange gaskets are essential for ensuring a tight seal between two flanged connections. Choosing the right type of gasket is vital to prevent leaks and maintain system integrity. Let me walk you through some of the most commonly used types of flange gaskets in the valve industry.
1. **Flexible Graphite Composite Gasket**
This is one of the most widely used gasket types. It consists of a thin carbon steel or stainless steel plate (about 0.5 mm thick) sandwiched between two layers of flexible graphite, making the total thickness around 3 mm. These gaskets have good resilience after compression, which helps prevent damage from excessive tightening. The middle flange typically has a small gap, allowing for some flexibility during installation.
2. **Metal Wave Gasket**
Made from mild steel with a thickness of approximately 0.8 mm, this gasket is corrugated to create a wave-like pattern. When compressed, the peaks of the wave deform to create a tight seal. Due to its thin profile, the final thickness after compression is only about 0.5 mm, resulting in minimal or no visible gap between the flanges.
3. **Rubber Asbestos Board Gasket**
These gaskets are often used in low-pressure water systems. However, they have limited elasticity and tend to deform easily under high temperatures. If the temperature causes the bolts to expand, the gasket may not compensate effectively, requiring increased clamping force to maintain the seal. This type of gasket is no longer commonly used in modern petrochemical applications due to safety and environmental concerns.
4. **Spiral Wound Gasket**
This is one of the more complex gasket types used in valve systems. It’s designed to provide a reliable seal without leaving any noticeable gaps. The sealing effect is achieved by controlling the compression depth within the valve body. Typically, the compression range is between 0.8 and 1.2 mm. The gasket is slightly thicker than the valve body depth, ensuring proper contact and pressure distribution.
The compression can be controlled using bolt tightening force to ensure adequate sealing pressure without overloading the gasket. Proper design allows the gasket to deform freely while maintaining structural integrity. In some cases, a small gap may appear, but it doesn’t affect the overall sealing performance.
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