Page 117 - Machinery Component Maintenance

100 Machinerv ComDonent Maintenance and Reuair

must be maintained to assure proper hydration of the cement. All of this
seems to be relatively simple; but even a slight deviation on any step can
result in a poor quality foundation.
The United States and other industrialized countries have no shortage
of quality construction materials, good construction equipment, capable
labor pools and excellent transportation networks. When foundation
problems occur and are attributed to faulty construction, the root cause is
often overconfidence or lack of proper supervision.
When construction is carried out in the developing countries or in re-
mote areas of the world, problems associated with maintaining good con-
struction practices can greatly increase. Good equipment and spare parts
may be difficult to find, and then only at great expense. The local labor
force may be semi-skilled or unskilled and there may be language barri-
ers. Local laws may restrict the importation of quality construction mate-
rials. Suitable means of transportation may be in short supply and deliv-
ery times increased many times. Proper supervision may be difficult to
obtain. The equipment owner should recognize these potential problems
and arrange for appropriate coverage. It may not be realistic to design
foreign plants with only U.S. construction capabilities in mind.
Many foundations fail because of operating conditions. When equip-
ment is modified to increase its service rating, it may no longer be in
balance. Failure to maintain the ignition system can cause severe unbal-
anced forces and rough-running equipment. Failure to regrout when nec-
essary can multiply the dynamic forces exerted on the foundation because
of progressing vibration. Any or all of the conditions which deviate from
the original design concept can, in time, damage the underlying founda-
tion.

Methods of Repair
Because foundation cracks are seldom noticed until they are called to
the owner’s attention by the regrouting contractor, repairs are usually
carried out at the time of regrouting. There are many variations in repair
technique. The best choice usually depends upon access to the founda-
tion, availability of alloy steel stud bolts and the urgency of returning
equipment to service.
On compressors and gas engines, cracks parallel to the crankshaft oc-
cur most frequently at the trough below the oil pan and extend through
the block to the mat below. Figure 3-18 illustrates a method of repairing
such cracks by drilling horizontal holes equally spaced from one end of