32
|
July - August 2018
|
www
.
machinerylubrication.com
A fter developing a lab
in the power plant and
focusing primarily on
analysis of oils from the
plant's critical components like
turbines, pumps and large motors, I
was approached one day by one of
our valve engineers. e question:
Could I also analyze greases? I had
been training in analytical ferro-
graphy and had the equipment at
my disposal. I was also aware of a
"grease solvent" and a special process
to dissolve the grease using glass
beads. Armed with that equipment,
I instructed the engineer to start
bringing me samples.
After a month, I had received
nearly 400 grease samples and
had dissolved them all. I spent
countless hours at the microscope
identifying the particles I saw. I
wrote reports for each sample and
created a summary, showing my
"dirty dozen" of the worst valves. I
felt satisfied that I had taken on this
new challenge and come up with
valuable information for my plant.
However, after reviewing my report
and investigating the valves I had
targeted, the valve engineer had bad
news for me. Some of the valves that
I had identified as the worst actors
were found to be in good shape. In
other cases, there were known bad
actors that I had identified as being
fine. In other words, I was told that
they had no further need for my
services on valves.
How could I have gotten things
so wrong? I looked back over my
notes a nd took a second look
at my ferrography slides. Had I
misidentified the samples? Had I
missed some clear signs that the
separated particulate was telling me?
After a review, I couldn't see where I
had fouled up. I returned to the engi-
neer and asked a question that should
have been the very first one I asked at
the start of the project: How were the
samples taken? e answer gave me
insight into the problem.
Grease Sampling
Methods Matter
GREASES
Rich Wurzbach
|
MRG Labs
"The best
analysts
at the top
laboratories
in the world
cannot
produce
meaningful
results from
samples
that have
been taken
incorrectly."
Figure 1. A motor-operated valve (MOV) lubrication test stand