Study on Stern Tube Sealing System

(Blister of Sealing Ring)

Abstract

The blister which is broken out on sealing rings is the most serious problem to stern tube seals and a study has been carried out to make clear it.
Through the investigation and analysis of blisters on sealing rings after the use, the following matters were found; blister is not caused by the defect of material and blister is closely related to the existence of sea water. Then blisters could be successfully broken out in a small test stand and various tests were conducted to examine relations between the blister and test conditions such as temperature, pressure, circumferential speed, environment (existence of water) and shaft eccentricity (repeated stress) . Another tests were also carried out with sealing rings which have the different sectional shape and materials.
The generating mechanism of blister was hypothesized and the prevention measures were considered based on the above test results.