15 August 2002
Operation. During operation, fresh water is taken into a tank on the
Wheeler car and heated near boiling with steam. The heated water is then pumped
through the washdown line into the ship's oil tanks. The hot water loosens the sludge
and converts it into a froth. The dirty water and froth are then removed by the suction
line and pumped into a tank on the flatcar.
Compressed Air Outlet in Wheeler Manhole. Provide a compressed air
supply outlet in the Wheeler manhole if it is contemplated to remove the sludge from the
Wheeler tank into an auxiliary tank on the flatcar.
Compressed Air Outlet at Sludge Receptacle. If the Wheeler unit is to
be removed from the dock site and emptied into a sludge receptacle at some other
location in the yard, provide the compressed air outlet at that point instead of in the
Manholes. The size and type of services and the number, spacing, and
location of manholes and other operating features are, to some extent, a matter of
judgment. In general, Wheeler manholes are installed opposite each service gallery or
group of service outlets if the gallery is continuous. The manhole will be best placed
adjacent to the outer crane rail. The latest experiences with the newest installations
should be investigated.
Oxygen and Acetylene. Oxygen and acetylene are required for cutting
metals, brazing, heating, and welding operations. Graving docks are, for the most part,
not equipped with a central oxygen and acetylene distribution system, and consequently
are supplied from individual portable tanks (bottles or cylinders). The provision of a
central distribution system should be considered in a new dock construction and in
existing docks where large quantities of these gases are required. If distribution
systems are planned, use the criteria below.
Location of Piping. Never run mains for these gases in a pipe tunnel or
an enclosed or partly enclosed service gallery, because of the extreme hazard involved.
Locate both mains and outlets above extreme high water to prevent contact with oil
floating on the water surface during flooding of the dock. Mains are best located in a
special open slot formed as an integral part of the coping curb, or placed on the wall of
the dock below the coping elevation, and protected from damage by a heavy fender
Place service outlets under open protective hoods above the coping level
or on the inner faces of the coping line. Temporary connections to the dock floor may
be made after each dewatering if distribution to the floor level is required.
Oxygen. For oxygen piping, use standard weight, black steel, seamless
tubing with beveled ends for welding. Pipe should be factory washed.
Sizes. Generally, provide these ranges of sizes:
main from supply to side of dock, 50.8-76.2 mm (2 or 3 in),