construction of the machine. Any special instructions on any of the drawings for
disassembly or reassembly should be noted. Any special tools listed in the drawings
should be located, or if not onsite, purchased or fabricated.
A list of weights of all of the machine's components should be made from the
drawing information. If the weights are not listed on the drawing, approximate
weights must be calculated. This list is essential in determining what rigging will be
required for the overhaul.
Drawings of the powerplant should also be studied to determine where the major
components from the unit can be stored. The space available and the allowable floor
loading must be taken into account. It may be necessary to store some parts outside
of the plant. If this is required, some provision must be made to protect these parts
from the elements.
Lifting devices and rigging
All of the rigging that will be required during the overhaul, such as slings, eyebolts,
and shackles, should be on hand well before the overhaul is to begin. The required
rigging for each component should be determined based on the list of weights.
Rigging already onsite should be inspected to make sure it is safe for use. Special
lifting devices supplied by the manufacturer, such as for the generator rotor or
turbine shaft, should be located and inspected. Dynamometers or crane scales can be
very helpful during an overhaul. A calibrated dynamometer can tell how much
weight is being lifted during a single point lift or how much weight one leg of a
multileg sling is lifting. This can prevent overloading the rigging when lifting parts
that may be stuck, such as the turbine headcover, or when some of the fasteners
have been accidently left in place. If a dynamometer is already onsite, it should be
calibrated before the overhaul begins.
Sending personnel who will be involved with the rigging to a rigging class should be
considered. These classes provide training in proper rigging procedures, inspection
of cranes and rigging equipment, and proper operating procedures for cranes.
A set of two-way radios can be very helpful in communicating with the crane operator.
Voice-activated, headset-type radios keep hands free to allow the signaler to make hand
signals and the crane operator to keep his hands on the controls.
A careful inspection of the powerplant crane should also be accomplished before the
overhaul. Consideration should be given to hiring a consultant, experienced in crane
inspections, to check out the crane and provide recommendations. Besides inspecting the
wire rope, brakes, hooks, hoist motors, and gear boxes, operational tests should be
performed. It is very