f) Where piles are necessary, lateral forces may be resisted by
battering a portion of the piles. Concrete piles, if used, should be
reinforced for at least the upper one-third of their length. Drive so top
of pile will project into diesel foundation block or base slab a minimum of
6 in (152.4 mm).
g) For small units, isolated foundations may not be necessary,
instead vibration isolators might be employed. Vibration isolators are
required when recommended by the engine manufacturer, such as for units
which come "skid-mounted", that is mounted on structural steel subbases.
h) Seismic restraints are needed for each unit located in an
International Conference of Building Officials, (ICBO), Uniform Building
Code (UBC); risk zone 3 or 4. Geographic locations of UBC seismic risk
zones are indicated in NAVFAC P-355, Seismic Design for Buildings, refer to
5.4.14 Cranes for Engine Servicing. Use NFGS 14334, Monorails with Manual
Hoist; 14335, Monorails with Air Motor-Powered Hoist; 14336, Cranes,
Overhead Electric, Overrunning Type; and 14637, Cranes, Overhead Electric,
Underrunning (Under 20,000 Pounds, as appropriate and NAVFC DM-38.01,
220.127.116.11 Sizing. Hoists should be sized for the servicing of engine and
generator components. Cranes should not be sized to extend over the entire
engine operating area, but only over engine-generator units and their
associated laydown space area. Follow the engine-generator unit
manufacturer's recommendations for crane and hoist capacities. Hoist
capacities of 1 to 2 tons (900 to 1,800 kg) are usually adequate for
smaller-sized generating units and capacities of 3 to 5 tons (2,700 to 4,500
kg) are normally adequate for larger-sized engine-generating units.
18.104.22.168 Electric Operation. Hoists should be electrically powered for
2,000 kW units and larger. Plants with 500 kW to 1,000 kW units should have
manually operated cranes and hoists. Plants with smaller units should be
provided with monorails and manually operated hoists.
22.214.171.124 Openings. Where hoists are provided to service equipment in
basement or lower floor areas, openings should be provided in ground level
floor slabs to allow penetration to the equipment in the lower areas. Fit
openings with removable gratings. Hoist lengths should be adequate to serve
the upper and lower plant levels.