Page 75 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

60 Practical Machinery Management for Process Plants

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Figure 1-27. Centrifugal pump with flinger spool.

mist lubrication or properly compounded synthetic oils of the diester and/or
polyalphaolefin type. Many refineries have stopped using cooling water in
pump applications with fluid temperatures around 740°F. l6
Similarly, a large number of pump users have come to realize that water-
cooled pump support pedestals represent a serious liability at worst, and an
unnecessary operating expense at best. Unforeseen corrosion incidents have
led to the collapse of pedestals, in turn causing disastrous pump fires. Align-
ment of driver and driven shafts with predetermined offset values have
proven satisfactory in every case.
Assembly-induced bearing problems also deserve attention. Rolling ele-
ment bearings furnished with plastic cages can suffer damage when over-
heated in defective heaters. They will be destroyed when heated by open
flames, a practice observed on the assembly floor of a pump manufacturer in
the 1980s. Do your maintenance/technical personnel know which code letter
identifies plastic cages? The answer is “P,” for SKF bearings. Do they know
that the letter directly behind the bearing identification number identifies the
load angle and that dimensionally interchangeable angular contact bearings
using the same number, but differing in just this one letter, may have allow-
able load ratings that differ by a factor of 8: l? Compelling reasons for devel-
oping a purchase specification for your rolling element bearings, and even
more compelling reasons for personnel training!

References
1. Dufour, John W., and Nelson, William E., Cenrrifirgal Pump Soui-ce-
book, McGraw-Hill, New York, NY, 1993.