Efficient Plant February 2018 - 18
feature | reliability strategies
While a power plant's fractured oil plug seemed
like a small failure, the root cause suggested
larger, more costly incidents could follow.
Randall Noon, P.E.
THE FOLLOWING CASE study
involves a fractured oil plug in a power
plant. In itself, a fractured oil plug isn't
a significant failure in a large industrial
facility. However, even back-of-theenvelope analyses of seemingly small
failure incidents can reveal larger
patterns that should be addressed.
INITIAL FAILURE STORY
The oil plug shown in the above
photograph had been removed from
a 300-hp vertically mounted electric
motor. That motor drives a mixed-flow,
single-stage vertical pump in a power
plant. The pump feeds cooling water
from a river to various heat exchangers.
The plug is from the lower oil reservoir
that services the lower motor bearing.
An upper reservoir services the motor's
The fracture was discovered when
the plug was removed to collect a
lubricant sample for periodic analysis. Leakage from this plug had been
occasionally reported in the past. Each
time a leak was noted, a mechanic was
dispatched to fix it.
No other information was supplied
at the time the photograph was pro-
Following maintenance recommendations for inexpensive components, such as the oil plug in
the inset (above), can prevent damage to much larger, more expensive equipment.