Page 166 - Know and Understand Centrifugal Pumps

Pump and Motor Alignment

+ .015" - .010"
Fiaure 10-10

7. Shims

w Spacer shims should be made of 304 stainless steel, except with
chlorine and hydrochloric acid service. In these services, use
Mylar shims to resist corrosion.

w It is best to use the thickest shim possible instead of numerous
thin shims, which can suffer fi-om compression. Never stack
more than 3 shims under an equipment foot.
w Measure shims to verify their thickness and tolerance, especially
thin shims (those less than 0.005 inch).
w Avoid the use of shims with the thickness stamped on the shim
face.
w Use shims large enough to completely cover the equipment
footprint.
w Avoid rust, scratches, gouges, creases, indentations, hammer
blows and dirt.
w Install the shims sliding them under the machinery footprint,
until contact is made with the anchor bolt. Then move the shim
back away from the bolt shaft to avoid interference with the
threads and to assure tolerance.

8. Alleviate any possible pipe strain, a force imposed by the piping that
can distort the pump casing.
w Pipe strain is normally caused by misalignment between the
piping and the pump nozzles, improper pipe supports, or
thermal expansion in the system.
w Don't connect the piping to the pump until the cement base
and grouting is fully cured, and all foundation bolts are
tightened.

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