Shaft Seals

Teignbridge supply three different types of seal. These are: lip seals, face seals and gland seals. These are all water lubricated.

Lip Seal

This is probably the simplest of the seal designs. It consists of a rubber ring, with a lipped profile supported by a spring, contained in a housing. The rubber lip seal runs on the shaft to form the seal.
This seal is generally used on:
Pleasure craft. Light duty, low pressure sealing, where low cost is required.

Advantages of this seal: Disadvantages:
It requires little attention other than ensuring that a water supply is maintained during operation. There is generally no back up for the seal in case of failure. Classification societies require an emergency built in back-up seal, generally inflatable. The rubber ring needs replacing at shorter intervals than the other seals. The ring gradually wears a groove in the shaft and so a replaceable liner sleeve is recommended.

Face Seals

This seal consists of two parts with polished faces. One part is fixed to the shaft and rotates with the shaft and the other face part is stationary. The two faces are pushed together to form the seal, usually by a rubber sleeve or gaiter.
This seal is generally used on:
Larger vessels. Heavy duty. Medium pressure sealing.

Advantages of this seal: Disadvantages:
It requires little attention other than ensuring that a water supply is maintained during operation. The face seal will eventually need to be replaced but will operate for longer periods than the lip seal. Some seals have no back up for the seal in case of failure. Classification societies require an emergency built in back-up seal, generally inflatable.
The faces can sometimes stick together when not in use and some manufacturers recommend that the seal is moved before starting to rotate the shaft to prevent sticking.

Gland Seal (or stuffing box)

This is a traditional seal that consists of a housing with a recess that is fitted with coils of a packing material and compressed onto the shaft with a pusher to form the seal.
Seals generally used on:
Working and fishing boats. Heavy duty. Medium to high pressure sealing.

Advantages of this seal: Disadvantages:
Generally considered to be the safest of the seals. It requires little attention other than ensuring that a water supply is maintained during operation. The packing material needs replacing at long intervals. An emergency back-up seal is not required. Occasional adjustment is required to maintain a seal.