What are the reasons for the failure of sealing performance of gate valves?

The sealing performance failure of gate valves is mainly caused by the following reasons:

Sealing surface factor

Wear and tear: Frequent opening and closing of gate valves, long-term friction between sealing surfaces, will gradually cause the material of the sealing surface to deteriorate, resulting in a decrease in sealing pressure and a deterioration of sealing performance. For example, in pipelines transporting media containing solid particles, the particles will exacerbate the wear of the sealing surface.

Corrosion: If the medium is corrosive, it will cause chemical erosion to the sealing surface, damaging the structure and performance of the sealing surface material. Strong acid and alkali media can cause pitting and pitting corrosion on the metal sealing surface, affecting the sealing effect.

Damage: During installation, transportation, or use, the sealing surface may be damaged by external forces such as collisions, scratches, etc., resulting in defects such as cracks and gaps, leading to poor sealing.

Valve seat and gate issues

Loose valve seat: If the connection between the valve seat and the valve body is not firm, the valve seat may loosen under the action of changes in medium pressure and temperature, causing the relative position between the sealing surfaces to change and resulting in sealing failure.

Gate deformation: When the gate is subjected to uneven force or high temperature, it may deform, causing the gate to not fit tightly with the valve seat and resulting in leakage. For example, if a gate valve operates for a long time under high temperature conditions, the gate may deform due to uneven thermal expansion.

Improper operation and maintenance

Inadequate closure: The operator did not fully lower the gate valve when closing it, resulting in gaps between the sealing surfaces and causing medium leakage.

Maintenance deficiency: Long term lack of maintenance can lead to the accumulation of impurities, dirt, etc. inside the gate valve, affecting the sealing performance of the sealing surface. Meanwhile, the lack of regular inspection and replacement of seals can also lead to a decrease in sealing performance.

Influence of medium characteristics

Pressure fluctuation: Frequent fluctuations in medium pressure can cause unstable impact forces on the gate, affecting the sealing fit between the gate and valve seat, leading to seal failure.

Temperature variation: The temperature variation of the medium can cause thermal expansion and contraction of various components of the gate valve. If the expansion coefficients of each component are different, thermal stress will be generated, resulting in deformation or loosening of the sealing surface and affecting the sealing performance.