30 Sep 94
(4) Although cranes can be derailed or over-
performance of these systems is primarily governed
turned due to earthquake ground motions, this usually
by the adequacy of component anchorage. Issues
occurs on soft soil sites where ground motion ampli-
related to anchorage have been discussed earlier.
Some equipment, such as air conditioners and fans,
fication or soil failures occur. Cranes on hydroelec-
may have vibration isolators incorporated into their
tric power projects are rugged and not expected to
design. Seismically induced motions to these isolated
experience damage due to earthquake ground
systems may cause misalignments, impacting, or
binding of moving parts. Small air- and motor-oper-
ated valves supported by the piping system may
(5) Critical spare parts, such as bushings, should
experience significant amplification due to seismically
be anchored to substantial racks that are anchored and
induced motions. These components are quite rug-
safe from secondary damage (Figure B-36).
ged, but control lines (either air or electrical) con-
nected to the operating device must be provided with
sufficient slack to accommodate the motion of the
piping system. Some failures have occurred when
inadequate clearance was provided around the devices
so that they were damaged when they impacted other
equipment or the structure when the piping system
Figure B-36. Storage of critical spare parts
d. Generator thrust bearing lubrication system.
The continued operation of the main thrust bearing
lubrication system is vital. The integrity of the pip-
ing system and pumps is necessary. As noted earlier,
piping is seismically rugged if heavy components,
Figure B-35. Control console anchorage. Control
such as tanks, are well anchored (Figure B-37).
consoles should be securely anchored. This con-
Components in the power supply must also continue
sole in a dam is anchored with friction clips, which
to function. Thus, unit substations and motor control
centers must be anchored. Comments contained in
paragraph B-5c also apply to this system.
systems, if properly anchored and braced, perform
well during earthquakes. The Sheet Metal and Air
system. The continued operation of the turbine
Conditioning Contractors National Association has
bearing lubrication oil cooling system is required
guidelines for the design of seismic restraints for
(Figure B-38). The comments in paragraph B-5d also
mechanical and plumbing piping systems.
apply to this system.
(3) Fire protection systems installed under
National Fire Protection Association (NFPA) 13, will
have adequate seismic protection.