FSM
Rotary & Sierra
Section:
Sheet No:
Date:
Superceds:
A General
7
March, 2003
N/A
Long Term Storage, All Motors
Occasionally, job conditions result in delays from time of compressor delivery, to time of actual start up. There is
an extensive write up covering suggested preservation procedures necessary to protect the compressor package,
the air end, the controls, and motors during this period. This procedure is called “Preparation for Long Term
Storage”.
Among other items, hand rotation of motors, along with a written record of motor bearing greasing intervals during
storage is required.
It is a fact, however, that even under the best of conditions, ball or roller bearings will eventually begin to
accumulate pit corrosion at the points where the bearing rollers or balls contact the bearing inner and outer races.
These areas of point contact, are subjected to the full weight of the motor rotor and as such are subject to high
unit loading, under static conditions. This high load forces out the grease between the bearing and race surfaces,
leaving metal-to-metal contact between ball/roller and bearing race.
At these points of high unit load and metal-to-metal contact, fretting corrosion can begin. Once begun, this
deterioration will lead to bearing failure regardless of future bearing greasing practices.
Experience has shown that periods of storage exceeding two years are likely to develop the early stages of
this type of bearing corrosion.
Therefore:
If a compressor and its attendant motor have been in storage for more than 24 months from date of
arrival at the jobsite, it is strongly recommended, that the motor be removed from the package, and sent to the
appropriate motor shop for dismantle, bearing inspection and bearing replacement if damage is noted. If there is
any doubt as to bearing condition, both bearings should be replaced.
Pjm/03/19/2003
FIELD SERVICE MANUAL
Information for use of Ingersoll-Rand and authorized Distributor personnel