Causes of Gasket Seal Failure
Gasket is the basic element of static seal of centrifugal pump and is widely used. The selection of gaskets is mainly determined by factors such as pump conveying medium, temperature, pressure and corrosion. When the
temperature and pressure are not high, non-metallic gaskets are generally used; when medium pressure and high temperature are used, non-metallic and metal combined gaskets are used. Non-metallic gaskets are most
commonly used in pumps, and their materials are generally paper, rubber and PTFE.
When the temperature does not exceed 120°C and the pressure is below 1.0Mpa, green shell paper or molded paper gaskets are generally used. If the conveying medium is oil and the temperature is between -30 and 110 °C,
the NBR with better aging resistance is generally used. When the conveying medium is at -50～200℃, it is more suitable to use fluororubber. Because in addition to oil resistance and heat resistance, its mechanical strength
is also its main feature.
In chemical pumps, because the transported medium is corrosive, PTFE is generally used as the gasket material. As the pump is used in more and more fields, more and more types of media are transported. Therefore, when
selecting the gasket material, you should consult the relevant information or make the correct choice through experiments.
The main reasons for gasket failure are as follows:
1. The internal organization or thickness of the gasket material is uneven, and the cardboard with cracks or wrinkles is used, so that the gasket itself forms a gap. When the force acting on the gasket makes the elastic deformation
of the gasket insufficient to completely When filling these gaps, leaks are inevitable.
2. The material of the gasket is not suitable for the medium being conveyed. Due to the diversity of chemical properties of the chemical products delivered by the pump, and the addition of a small amount of additives to the
fuel in order to improve the combustion value of the fuel or change its combustion products, some properties of the fuel have changed, so It is not easy to select the gasket material suitable for the conveying medium, so it
often occurs that the gasket is eroded due to incompatibility and leaks.
3. The pressure acting on the gasket is insufficient. Because there are always microscopic unevenness on the sealing surface, sometimes a number of annular grooves are machined on the sealing surface. Fill these gaps.
The compression force of various gasket materials is usually given in the gasket manufacturer's sample or product manual, and can also be determined through experiments. Due to the failure to reach the required pressing
force of the gasket during assembly, or the reduction of the pressing force due to the loosening of the pressing bolt due to vibration during long-term operation, and the loss of original elasticity due to the aging deformation
of the gasket material, the gasket will be damaged. Leakage due to failure.