Page 33 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

18 Major Process Equipment Maintenance and Repair

tor alignment, get a book and learn, or purchase one of the small
hand-held calculators now available that are based on this system.

3. Measure and adjust the distance between the driver and the pump
shaft ends (D. B . S. E .) . This distance should be in accordance with
the pump layout drawing and within the tolerance provided by the
coupling manufacturer or guideline value of Chapter 5, Volume 3
of this series. The D.B.S.E. should be set with the pump and
driver shafts pulled toward each other for turbine drives and mo-
tor drives with antifriction bearings. For motor drives with sleeve
bearings, the D.B.S.E. should be set with the motor shaft at its
magnetic center.

3. Measure and adjust the distance between the driver and the pump
shaft ends (D.B.S.E.). This distance should be in accordance with
the pump layout drawing and within the tolerance provided by the
coupling manufacturer. The D.B.S.E. should be set with the pump
and driver shafts pulled toward each other for turbine drives and
motor drives with antifriction bearings. For motor drives with
sleeve bearings, the D.B.S.E. should be set with the motor shaft at
its magnetic center.

4. Both the driver and pump shafts should be checked for mechanical
runout using a dial indicator. Mechanical runout should not ex-
ceed .002-in. total indicator reading (TIR).

5. Driver-to-pump and pump-to-driver alignment targets should be
provided to the installation contractor before starting the align-
ment. These targets should include allowances for thermal growth
of hot pumps and steam turbines. If the actual cold targets are not
provided, the amount of vertical growth due to temperature may
be estimated using the following formula:

6. Initial alignment should be made at ambient temperature and
"pipefree"-no pipe forces or weight on the equipment (pump and
turbine flanges should be unbolted).

7. To eliminate adding mechanical runout to alignment error, indica-
tor readings should be taken by turning the pump and driver shafts
together.