Four Factors That Compromise the Sealing Performance of PTFE Gaskets

The PTFE gasket is manufactured by uniformly dispersing high-purity graphite and glass fiber—both inorganic fillers—into a PTFE matrix, followed by processing. Its multidirectional fibrous structure provides exceptional resistance to solvent attack, eliminates cold flow and stress relaxation, and ensures reliable sealing over the long term. External factors such as deformation of pipeline components can adversely affect the seal; in particular, vibration can cause cyclic variations in the clamping force between the sealing surfaces, leading to seal failure. To achieve optimal sealing performance, it is recommended to carefully consider the following factors:

1. Temperature of the application site

The temperature of the process medium can immediately compromise the sealing performance of PTFE gaskets; therefore, the material selected must be rated for at least the same temperature as, or higher than, the operating temperature. In addition, temperature fluctuations can also rapidly affect the sealing performance of PTFE gaskets, leading to leakage.

2. Sealed substances

To achieve superior sealing performance, it is essential to select the raw materials for PTFE gaskets based on the specific physical properties of the sealing medium, including temperature, operating pressure, pH, and acidity/alkalinity.

3. Gasket Material

The raw material of PTFE gaskets is prone to elastic or plastic deformation under preload, thereby sealing off the pathways for fluid leakage and enhancing the sealing performance; however, PTFE gasket materials generally cannot withstand high-pressure fluids. Moreover, different gasket materials exhibit varying degrees of corrosion resistance, temperature resistance, and density, resulting in differences in the types of sealing media they can accommodate and the operating conditions under which they are suitable.

4. Condition of the Sealed Surface

A rough or non-smooth surface on the sealing interface can adversely affect sealing performance; a smooth surface on PTFE gaskets is beneficial for achieving a reliable seal. Due to PTFE’s inherent ability to deform easily, surface roughness has a relatively minor detrimental effect on sealing characteristics. In contrast, for rigid gaskets, surface condition significantly impacts sealing performance: the greater the total contact width between the sealing surfaces and the gasket, the better the seal; however, under the same clamping force, a larger contact width results in lower specific sealing pressure.

PTFE sealing gaskets contain no adhesives, making them unlikely to adhere to the sealing surfaces; their consistent performance on the same sealing surface facilitates installation, eliminates the risk of embrittlement, and allows for long-term storage. By addressing the aforementioned four factors, the practical application of PTFE sealing gaskets can be significantly improved.

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