Page 400 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

378 Major Process Equipment Maintenance and Repair

6. Lift the rotor slightly and remove the bottom bearing liners by roll-
ing them away from the locating lugs. The rotor shaft will rest on
the shaft sleeve seals (47) when the bottom liners are removed.

Clearances
Bearing liners used with rotors designated Class 1 and 2 provide a cold
diametral clearance of .006 in. (0.15 mm) to .009 in. (0.23 mm). Diame-
tral journal bearing clearances are .0035 to .0055 in. (0.09 to 0.14 mm)
when turbine is equipped with a Class 3 rotor (refer to Figure 9-10).

To Check The Bearing Liner Clearances:
1. With the top liners (16, Figure 8-5) removed, place a piece of Hasti-
gage@ radially on the shaft journals.
2. Place the top bearing liners (16) over the shaft journals.
3. Place the oil rings (49) in the slotted guides in the top bearing lin-
ers.
4. Replace the bearing caps. Be sure the top bearing liner locating lugs
engage the grooves in the bearing caps.
5. Insert dowels (14) and tighten bolts (13).
6. Remove the bolts (13). Lift the bearing caps approximately 1 in.
(25 mm) and pry the top liners (16) from the caps with a screw-
driver.
7. Remove bearing caps and top liners and measure the Plasti-gage@ to
determine the clearance between the shaft journals and top bearing
liners.

AdJustments

Bearing liners are not adjustable. They should not be filed, scraped,
shimmed, fitted or altered in any way. Worn bearing liners can lead to
vibration and other operational problems. Replace worn bearing liners if
the clearances exceed the maximum shown in Figure 8-10 by .002 in. (.051
xmn). Bearing liners should also be replaced if inspection shows signs of
scoring, wiping, cracking, flaking or loose bonding between the babbitt and
the steel backing.
Assembly

1. Clean the flanges on the bearing caps and housings.
2. Drain and clean bearing housing reservoirs and refill with clean oil
(refer to Table 8-8).
3. Lift the weight of the rotor and roll the bottom bearing liners (15)
around the shaft journals and into the bearing housings. Be sure