Which material is good to choose for sealing gasket? After reading this article, you will understand thoroughly (below)

Release time：

2022-12-08

Category：

Industry News

3. PTFE

Commonly known as "plastic king", it is a polymer compound formed by polymerization of tetrafluoroethylene, which has excellent chemical stability and corrosion resistance. It is widely used in the chemical and pharmaceutical industry and can be called the originator of the gasket industry.

Pros:

High temperature resistance - the operating temperature is up to 250°C.

Low temperature resistance - good mechanical toughness; Even if the temperature drops to -196°C, the elongation of 5% is maintained.

Corrosion resistance - for most chemicals and solvents, it is inert, resistant to strong acids and alkalis, water and various organic solvents.

Weathering resistant – has the best aging life among plastics.

High lubrication – the lowest coefficient of friction among solid materials.

Non-adhering – is the smallest surface tension in solid materials and does not adhere to any substance.

Non-toxic - physiologically inert, as artificial blood vessels and organs long-term implantation in the body without adverse reactions.

Cons:

Easy cold flow and creep under pressure and high temperature;

The stress relaxation phenomenon is more serious;

The coefficient of friction is small, and the gasket tends to slip outward during preloading.

Precautions for use:

Due to the small coefficient of friction, it is best to use a concave-convex flange face. If a flat flange is used, the outer diameter of the gasket can contact the bolt, and the bolt can be used to prevent the gasket from sliding outward.

4. Metal-clad asbestos pad

Asbestos rubber sheet is used on the inside, and a composite gasket coated with metal sheet with a specific cold work process on the outside. Since asbestos fibers do not have direct contact with the medium, the leakage phenomenon caused by the decrease in fiber strength is avoided, thereby expanding the scope of use of asbestos rubber sheets.

Pros:

Strong, unbrittle, firm and strong.

Cons:

The rebound force is limited, and the flat surface of the flange and the large bolt tightening force are required to achieve good results.

Metal cushions can be made into various shapes, and are widely used in various heat exchangers, reactor covers, loading and unloading holes, manhole flanges, etc.

5. Metal winding pad

The metal winding

pad is made of high-quality metal strip and other alloy materials and graphite, asbestos, polytetrafluoroethylene, non-asbestos and other soft materials overlapping spiral winding, and the metal strip is fixed by spot welding at the beginning and end.

Features:

Suitable for a wide range of working conditions. It can withstand high temperature, high pressure and adapt to the use conditions under ultra-low temperature or vacuum.

Strong stress compensation ability. In the station with frequent temperature and pressure fluctuations, the sealing performance is stable and reliable.

Excellent sealing performance.

The surface accuracy of the flange in contact with the gasket is not required.

Easy installation and low gasket preload pressure.

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