Page 157 - Rotating Machinery Pratical Solutions to Unbalance and Misalignment

Advanced Machine Alignment
BORE READINGS

Some equipment will need to be aligned using a bore reading
rather than a rim reading. This is found in many large gas tur-
bine/compressor applications. A bore reading is simply an up-
side-down rim reading and can be handled as such in the
alignment process. All that is required is to set the positive (+) bar
sag at 6 o’clock and take the reading at 12 o’clock.

For a rim reading
set to + bar sag
Record the bore
reading

For a bore reading
set to + bar sag
Rotate in
normal
direction
Record the rim
reading

Figure 8-23. Bore Readings

VERTICAL PUMPS

In the case of vertical pumps, the first step is to remove all
old shims, clean the mounting surfaces, and then correct any soft
feet. The angularity is corrected first, and then the parallel offset.
Correcting the angularity is easily accomplished with the
face indicator when using the rim and face method of align-
ment. The pump is viewed from above and labeled as shown in
Figure 8-25.