Pag. 38/49
Doc. ISM0076_MANUALE_CN SEAL-MV_ENG_REV04.DOCX
b) It is recommended that when reassembling mechanical seal new "O" rings and gaskets be used.
c) Refer to manufacturers drawing for assembly of mechanical seal. Refer to mechanical seal section
within this manual for further details.
23.1.3.
Throat Bush (If fitted)
a) Check the throat bush and replace if required.
Note that the bush outside diameter should be the same diameter as the adjacent impeller wear ring.
23.1.4.
Shaft
Shaft (12) for scratches, nicks, burrs, and distortion; absolutely smooth surfaces and a straight shaft are
required.
After the shaft is inspected for damage as described above, it must be checked for straightness before
reassembling the rotating parts. When making the check do not turn the shaft in its lathe centers. It is
possible for the lathe centers of a straight shaft to be off center slightly, resulting in a false indication of
a
bent shaft.
1. Set shaft in soft-faced V-blocks, precision rollers (or equivalent).
2. Check straightness by taking dial indicator readings all along the shaft while it is rotated; total runout
of shaft must not exceed 0.04 mm (0.0015 in). If runout is exceeded shaft must be coldstraightened or
replaced.
Application of heat to straighten shaft will cause more distortion.
The term "soft-faced V-blocks" refers to V-blocks faced with metal that is softer than the shaft, for
example, V-blocks faced with copper.
23.1.5.
Gaskets and O-rings
After dismantling, discard and replace.
23.1.6.
Bearings
a) It is recommended that bearings are not re-used after any removal from the shaft. In any case the
bearings must be replaced not after 25000 operating hours.
b) If the bearing cannot be removed with the tools available never use a torch under any circumstances.
Split the outer ring with a small hand grinder, saw through the ball/roller retainer, and split the inner
ring about three quarters through with a grinder and break with a cold steel chisel.
Do not attempt to inspect condition of bearings until they have been cleaned.
c) Solvent for cleaning bearings should be in a clean container. Place bearings in solvent and let soak for
a short time. Agitate the bearing around near the top of the container, giving it a turn now and then until
it is clean. Rinse in a clean container of fresh solvent.
Do not spin dirty bearings. Rotate them slowly while washing.
d) Dry thoroughly cleaned bearings. If an air hose is used for drying, make sure it is clean dry air.
Do not allow the bearings to spin by force of air. Hold the inner and outer rings to prevent bearing from
spinning.
