Page 264 - Practical Machinery Management for Process Plants Major Process Equipment Maintenance and Repair

246 Major Process Equipment Maintenance and Repair

ening the bolts, check for distortion by placing a dial indicator on the
gear housing foot near the bolt to be checked. If the housing foot moves
when the bolt is loosened, then distortion is present, and the housing
needs more shims around the bolt. The gear housing should be checked
for distortion using this method at each foundation bolt.
After the gear unit is properly aligned to the first component and bolted
down free of distortion, a soft blue tooth contact check should be per-
formed. If the contact pattern is satisfactory, then proceed with the instal-
lation. However, in the event that the soft blue check indicates poor tooth
contact, shaft and coupling alignment and housing distortion should be
rechecked before proceeding with installation.
Before operating the gear unit, dowel it to the base or soleplate as rec-
ommended by the manufacturer, leaving room to redowel if necessary.
Doweling a gear unit before operating is very important since, as a gear
unit is heated and cooled, it will crawl on the mounting surface and an
alignment change may result. If instructions are not available from the
manufacturer, dowel the unit under the shaft for which alignment is the
most critical.
After doweling the gear unit, apply layout blue to the teeth as directed
for a hard blue tooth contact check, and then start the unit up and operate
it for a short period of time. NO272 Care should be taken in joining the
two coupling halves to observe any coupling match marks. Lubricate the
coupling and check for free axial movement of pinion and gear. After
shutting the unit down, check the tooth contact pattern as evidenced by
the wear-off of the bluing. If a satisfactory contact pattern is obtained,
proceed with installation. However, should the contact pattern be poor,
corrective measures should be taken as recommended by the manufac-
turer before going on with installation.
At this time, a hot alignment check should be made by running the gear
package until temperatures stabilize, shutting it down, and taking indica-
tor readings while the gear package is hot. Any corrections necessary
should be made while the unit is still hot. After complete correct hot
alignment is obtained and before the package cools off, the gear unit
should be redoweled to the foundation or base. When final coupling
alignment has been established and the gear has been redoweled, place
the coupling guards in position. Mzrning: Failure to use coupling guards
may result in serious injury to personnel.
Succeeding the installation of the gearbox, the installation of the third
machine element should follow along the same basic lines. Again, after
alignment has been completely finalized, coupling guards should be in-
stalled for protection.
When the entire machinery package has been completely and satisfac-
torily installed, it should be started up and operated. Special attention