Explosive Decompression

With the advent of the space age we are seeing this type of O-ring failure with increasing frequency. It might be termed O-ring embolism in that after a period of service under high pressure gas, when the pressure is reduced too rapidly, the gas trapped within the internal structure of the O-ring expands rapidly, causing small ruptures or embolisms on the O-ring surface.

 

FAILURE ANALYSIS
Explosive Decompression, or Gas Expansion Rupture is caused by high pressure gas trapped within the internal structure of the elastomeric seal element. Rapid decrease in system pressure causes the trapped gas to expand to match the external pressure and this expansion causes blisters and ruptures on the seal surface. If the volume of trapped gas is small, the blisters may recede as the pressure is equalized with little effect on seal integrity. Excessive trapped gas may cause total destruction of the seal. PREVENTION/CORRECTION
Suggested solutions to Explosive Decompression are as follows:
  1. Increase decompression time to allow trapped gas to work out of seal material.
  2. Choose a seal material with good resistance to explosive decompression.
  3. If problem persists and pressures are very high, consider use of Parker Metal Seals.
IDENTIFICATION OF INSTALLATION FAILURE
The seal subjected to Explosive Decompression will often exhibit small pits or blisters on its surface. In severe cases, examination of the internal structure of the O-ring will reveal other splits and fissures. Below are typical examples of this type of failure.

 

Explosive Decompression Example 1
Explosive Decompression Example
Explosive Decompression Example 2
Explosive Decompression Example
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