Page 315 - Reciprocating Compressors Operation Maintenance

3OO Reciprocating Compressors: Operation and Maintenance

CHROME PLATING PROCEDURE

The following procedures should be followed when applying chrome
plating to compressor crankshafts.

1. Areas to be plated shall be pre-ground, followed by magnetic parti-
cle and dye-penetrant inspection of all ground surfaces.
2. Shaft area to be chromed shall be shot peened, with care given not
to damage the collar surface.
3. Maximum chrome thickness shall be 0.030" (radial thickness).
4. Journals that are not too badly damaged may be cleaned with a belt
sander and hand stoned. Extreme care must be taken because it is
easy to get journal in an out-of-round condition, which will cause
further bearing failures.
5. Metal spraying has been successfully done on smaller shafts, but is
generally not recommended for large cranks.

Some other general repairs of crankshafts that can be done in the field
or shop include:

1. Straightening
2. Machine rod size journals undersize
3. Machining damaged key ways oversize and producing new key
4. Machining outside diameter and faces of flywheel fit and bushing
flywheel
5. Reaming damaged holes in shaft and flywheel and installing new
oversized studs
6. Boring and tapping damaged counterweight stud holes oversize and
producing new step studs

CERTIFICATION

Vendors should certify that the repaired crankshaft meets or exceeds
original engine or compressor manufacturer requirements with regard to
structural and dimensional integrity. Alternatively, a vendor should detail
all known deficiencies that could, in his judgment, affect the operational
serviceability of a particular shaft. This cataloging of deficiencies must