Page 287 - Steam Turbines Design, Applications, and Rerating

266 Chapter Thirteen

Figure 13.21 Failure of bearing due to water intrusion in lip
seal–equipped shaft system.

dual-face bearing protectors on gear units. The bearings or component
housings of gear speed reducers and increasers are among the hun-
dreds of shaft-driven and bearing-supported types of equipment that
can be effectively sealed with dual- (or double-) face magnetic seals. In
particular, many gear speed reducers have benefited substantially
from the virtual elimination of lubricant oil contamination. Cost justi-
fications for the projected gear life extension are readily available.
In particular, replacing lip seals with dual-face magnetic seals often
results in extending oil replacement intervals from one year to as
many as four years. Based on feedback involving cooling towers in
petrochemical plant locations where moisture intrusion has been elim-
inated, cooling tower gearbox failures should no longer occur. The ben-
efits often exceed conversion and upgrading costs by an order of
magnitude, and payback periods ranging from a few weeks up to three
months are not unusual.