Reliability Improvements
to a High Speed/High
Energy Pump
Ed Wilcox, Chevron Energy Technology Company
An analysis of solutions to improve reliability that include
changing to titanium on the impeller and inducer, and
modifying the gearbox seal, the secondary dealing system,
and the tilting pad bearing design on the output shaft.
The pump is a 300-hp integrally geared propylene product pump in a Gulf Coast olefins unit that operates at
25,000-rpm and produces 6000-ft of head (see Figures
1 and 2). The suction and discharge pressures of the pump are
Figure 1. Cross-section of pump.
250-psig and 1500-psig, respectively.
Two of these pumps were originally installed in 1984, with
a third installed in 1989 because of a unit expansion. Two eddy
current probes measure the high speed output shaft vibration
and are connected to an online vibration spectrum analyzer.
The reliability of the pumps was improved in 1995 when the
original stainless steel impeller and inducer were replaced with
titanium to raise the output shaft critical speed above the pump
operating speed.
In 2001 the reliability of the pumps became a large issue
when, due to business constraints, the unit reliability became
very critical. A total of seven failures occurred on the three
Reproduced with permission of the Turbomachinery
Laboratory ( http://turbolab.tamu.edu). From Proceedings
of the Twenty-Third International Pump Users Symposium,
Turbomachinery Laboratory, Texas A&M University,
College Station, Texas, pp. 1-5, Copyright 2007.
