More than 20 years ago, a major chemical manufacturer was
experiencing frequent failures of their pumps in ethylene service. They
had (and have) six 15-stage Pacific vertical can pumps installed and one
spare. Each pump has fourteen inter-stage assemblies, and head and
lower bearing assemblies.
These pumps were originally fitted with bronze bearings which were
failing within

one month of installation. Ethylene is a very light
hydrocarbon that creates problems in pump operation. Because of its low
viscosity, ethylene provides minimal lubrication to the rotating parts
of the pump. As a result, these pumps are prone to failure when running
with bronze bearings.