Page 408 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

386 Major Process Equipment Maintenance and Repair

housing and turbine casing, are used to correct any angular misalignment
and to position the turbine rotor axially in the turbine casing.

To Check The Alignment
1. Remove the rotor assembly from the turbine casing and clean the
shaft journals.
2. Apply a light coating of soft blue to both shaft journals.
3. Install bottom half journal bearing liners (15, Figure 8-5) in the bear-
ing pedestal and steam end bearing housing. Be sure the liners are
properly seated.
4. Lower the rotor assembly until the full weight of the rotor is sup-
ported by the journal bearing liners.
5. Rotate the rotor assembly one quarter turn in each direction.

Note: Ensure the rotor shaft is seated on the bottom of the bearing
liners and not moving sideways or upward while being ro-
tated.

6. Remove the rotor assembly from the turbine casing and check the
bearing contact.

Note: The exhaust end bearing pedestal and steam end bearing
housing are considered to be in alignment when bearing con-
tact with the shaft journals is no less than 85 percent along
the bottom of the bearing liners and when the contact along the
sides of the liners is parallel with the bearing bore and equal on
each side (See Figure 8-11).

To Correct Any Misalignment
1. Place shim stock, in increments of .002 in. (0.05 mm), behind the
spacers (24, Figure 8-5) to correct the misalignment.
2. Recheck the bearing contact and continue to add shims to achieve
proper alignment.
3. After the correct bearing contact is obtained, the shims must be re-
moved from each spacer, and the thickness of the opposite spacer
altered accordingly. (Surface grinding is the preferred method.)

Example: It is necessary to add .OM in. (0.10 mm) shim thickness
to the two bottom spacers, to achieve correct alignment;
.004 in. (0.10 m) must be ground from the two top
spacers to maintain the alignment after the shims are re-
moved.