Page 98 - Machinery Component Maintenance

Machinery Foundations and Grouting 81

vents penetration of lubricating oils into the foundation after start-up.
This sealing is particularly important in areas such as around the oil pan
trough which are usually flooded with oil. Paint will not usually stick to
concrete unless the surface has been sandblasted to remove the laitance or
unless a penetrating primer has been applied before painting. Some spe-
cialty coating manufacturers provide special primers for epoxy coatings
when used on concrete. Most of these special primers contain either ace-
tone or ketone solvents which are low in viscosity and water soluble.
When utilizing these primers, care must be taken to prevent build-up of
flammable vapors and breathing or contact with eyes or skin. Read the
warning labels on the containers.

Methods of Installing Machinery’
The four common methods of installing compressors in the order of
increasing foundation load requirements are shown in Table 3-3. Static
load ranges shown in the first column are relatively low compared with
the strength of the supporting concrete. What complicates the situation is
the combination of additional anchor bolt load, dynamic load and dramat-
ically lowered epoxy grout strength due to rising temperatures.
Skid mounting is an equipment packaging concept whereby partial
erection of the compressor and its related equipment are carried out un-
der shop conditions where quality control can be closely monitored. This
concept is ideal for equipment destined for offshore or remote locations
where accessibility and accommodations are limited or where skilled
manpower is not available. Packaging works well on portable units in the
lower horsepower range.
Job-site skid installation is progressively more difficult with increasing
compressor size because of the number of structural members required.
Most packagers do not provide access holes to permit grouting of internal
structural members. Those internal “I” beams anchored to the equip-
ment above are critical. Consequently, with typical factory design, grout
placement must be accomplished from the edges of the skid. Placement
of grout prepared to the proper consistency is difficult and often the criti-
cal members are left unsupported. When this occurs, a suspension bridge
effect is created, allowing excessive vibration to occur when the equip-
ment is operating. The obvious solution to this grouting problem is to cut
access holes in the field. This should be done only with the manufactur-
er’s approval, since otherwise the warranty may be voided. After grout-
ing, all access holes should be covered.
As mentioned earlier, most compressors leak oil. Because skids are
fabricated by strip welding rather than seal welding, oil gradually seeps