20. State about stern tube sealing with gland packing seal type.

-Gland packing seal almost used on small ships

-Its structure consists of simple stuffing boxes filled with packing material; usually rove cotton imbrued with tallow or graphite as a lubricant

-In the case of high duty packing the material may be white metal clad

-Gland packing can be lubricated by water or lubricating oil (usually by water)

-Packing quality are adjusted by tightening or loosening gland cover.

1- Propeller shaft

2- Stern tube

3- Gland packing

4- Gland cover

5- Metal bush

*Advantages:

-Simple and cheap.

* Disadvantages:

-Water always penetrates to the engine room.

-Longevity of the packing is low.

-Force of loosing and tightening must be suitable.

-Gland packing have to assembly onboard the ship…

*Application:

-This kind of shaft seal is only used onboard the small and the former ship.