Seals

2.2 Specify the consequences of failure

The failure of a seal usually means either the loss of system pressure or pollution of one fluid by the other. The probable mode (break, leak, wear) and manner (sudden, gradual) of failure should be considered. The consequences may vary between 'irritating', such as excessive wear in a bearing, and'catastrophic', such as the escape of a toxic gas. An assessment of both the consequences and the acceptable frequency of failure should be made so that adequate safety is assured. More than one sealing system may be necessary in extreme cases. The frequency of maintenance should be specified.