Seal failure index

2.0 Oil barrier seals

Oil barrier seal index

2.1 Floating bush seals

Click on photograph to enlarge
	Figure 2.1 Schematic diagram of floating-bush seal system
Main Characteristics	Floating-bush seals are commonly used on the shafts of process gas centrifugal compressors. Figure 2.1 shows the general arrangement, with mineral oil, normally the system lubricating oil, fed between a pair of floating bushes to about 5 m head above the pressure of the sealed gas.
Cause	Despite the pressure differential, some leakage occurs across the seal (the mechanism for this is not clear, but it seems likely to be precession of the seal ring about the shaft through slight departures from roundness in the seal ring bore or the shaft causing cavitation in the oil film.). High temperature occurs in the seal oil film because the high rate of shear and negligible cooling by the leaking oil. This can lead to chemical reactions in the seal that leads to failure.
Note
Possible Confusion with Other Types of Damage
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