Page 405 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

Steam Turbines and Turboexpanders 383

Replacement

1. Lower the rotor assembly to within 1 in. (25 mm) of full replacement
in the casing. Carefully guide the rotor while lowering it into the cas-
ing to prevent the disks (44 and 45, Figure 8-5) from contacting the
reversing blade assembly (37).
2. Position the oil rings (49) so they fall into the openings between the
bearing liner supports located in the bottom of the bearing hous-
ings.
3. Position the anti-rotation tab on the rotor locating bearing (50) to
engage the groove in the steam end bearing housing (21),
4. Slowly lower the rotor into the casing.
5. Check bearing housing alignment.
6. Replace the journal bearing liners and caps.
7. Replace the governor and connect the governor linkage (Refer to
Governor Maintenance Section).
8. Replace the carbon rings (9) top half packing cases (10 and 11) and
casing cover (3 and 64) as outlined in Carbon Ring Replacement
Section, and Assembly Section, earlier.

Exhaust End Bearing Pedestal Replacement
The exhaust end bearing pedestal (12 and 54) is attached to the turbine
casing by four socket head cap screws (23) and two combining studs
(17). The combining studs are threaded into the bottom half turbine cas-
ing and pinned to the pedestal.
Two dowel pins (25), pressed into the exhaust end of the turbine cas-
ing, position and hold the pedestal in correct horizontal and vertical par-
allel alignment with the steam end bearing housing (21 and 53). Spacers
(24), located between the pedestal and turbine casing, are used to adjust
and maintain proper angular bearing alignment.

Disassembly

1. Remove the rotor assembly as outlined in Removal Section, earlier.
2. Remove the hold-down bolts and dowel pins from the pedestal sup-
port feet.
3. Support the weight of the turbine exhaust end casing with a jack,
wooden blocks, or other adequate means.
4. Remove the tapered pins (18, Figure 8-5) from the combining studs
(17).
5. Loosen the four cap screws (23) three or four turns and pry the ped-
estal away from the casing until the spacers (24) are free to move.