Page 74 - Machinery Component Maintenance

Maintenance Organization and Control for Multi-Plant Corporations 59

Figure 2-18. Rotor History Chart

If you plan to remove compressor diaphragms, be sure to match mark
them as to their position in the case. Inadvertent mixing of inlet guide
vanes could alter machine performance! Be careful to stone down any
match marks which are placed in a machined area, such as the casing split
line. When the top half of a horizontally split compressor is removed, it
is a good idea to position the rotor with its thrust bearing as it was before
shutdown and check to see if the impellers are centered with the diffuser
flow passages.

Inspection

As the machine is being opened, pay particular attention to visible de-
posits. On machined sealing surfaces you may find telltale tracks of a
leak or wire drawing. Such leaks may indicate a need to check the flat-
ness and fit of the surfaces with lead wire or Plasti-Gage@, or simply bet-
ter attention to bolt torquing requirements. Fouling inside the flow pas-
sages of the machine will likely not be distributed uniformly from one
end to another. In a compressor, the gas will get hotter with each succes-
sive stage. With some gases this will bake the deposits in the latter stages;
with other gases, heavy, wet deposits will form in the first stages of the
machine. Get a sample of the deposits to determine, first, what they are
in order to see if they can be eliminated from the process. Failing that,
test to see if they can be dissolved in some suitable solvent, for either on-