Page 107 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

92 Major Process Quipment Maintenance and Repair

Based on IS0 1940 QUALITY GRADE G - 6.3
MAX. SERVICE SPEED RECOMMENDED TOLERANCE
OF ROTOR IN min-' IN gmm ROTOR MASS
IN hg

btO1:FoTdb
shaped I"S. im full
mcommended vnlw
planas. use onehall
the muanmendad
value for each plane.

3 --

30 --
1.- x 10-1 =.-In
I gmm I LO --

Figure 2-15. Balance tolerance diagram for rotor mass up to 50 kilograms.

lowance of 100 gram-millimeters equals an allowance of -139 inch-
ounces.

1. The impeller is mounted on a mandrel for balancing.
2. If it has a keyway, a key or half key must be installed.
3. Correction of unbalance is achieved by removal of metal from the
impeller shrouds, generally by grinding with a handheld portable
grinder (Figures 2-17 and 2-18).
4. Metal should not be removed from the outer M in. of the shroud,
and no more than 1/3 of the shroud thickness should be removed.