Gasket design for SF6 leakage

Leakage Causes and Gasket Design Considerations

Leaks in equipment often occur due to the deterioration of gasket materials over time and with use. Three critical factors influence gasket design and performance:

1. Hardening of Gaskets:
   High ambient temperatures and the heat generated by electrical currents passing through circuit breakers during normal operation can reduce the elasticity of gaskets, causing them to harden over time.
2. Chemical Attack:
   In substations, SF6 gas undergoes chemical changes due to arcing during current interruptions. These short-circuit events decompose the pure SF6 gas, altering its composition and potentially damaging the gaskets.
3. Corrosion:
   The filler materials used in equipment seals can be attacked by external environmental factors, leading to corrosion and eventual failure.

Sealing System Improvements

To address these issues, sealing systems have been enhanced:

• Previous Design:
  Two O-ring seals were placed close together, with a leak-checking system between them. Grease was applied to protect against airborne pollutants.
• Current Design:
  A new sealing system incorporates three seals in a specially shaped configuration. The main seal is shielded from both internal and external corrosion by two auxiliary seals. The seal is housed in a groove designed to prevent scratching during equipment assembly. Additionally, the main seal now features a larger surface area to minimize the risk of leakage, even if the metal becomes caught during seal assembly.

This improved design significantly enhances the reliability and longevity of the sealing system, reducing the risk of leaks and equipment failure.