15 August 2002
in a graving dock for heating, cleaning
equipment and tanks, and ship use. In northern latitudes, provision must be made for
heating those areas in which personnel must remain for lengthy periods, such as pump
rooms, motor rooms, caissons, toilets, and shower rooms. Use steam for deicing and
for keeping necessarily exposed fresh waterlines from freezing. Freezing may
sometimes be prevented by running a parallel steam line.
Quantity. Exact quantities of steam to be furnished to the ship are difficult
to determine. Changes in ship designs, variations in ships of the same class, and
differences in repair operations make close estimation of steam demand loads purely
academic. On the other hand, providing sufficient steam to take care of the total
maximum demand load that could occur under the worst conditions would result in a
grossly over-designed and expensive system. MIL-HDBK-1025/2 Dockside Utilities
gives the design steam demand for various ships.
Use engineering judgment to determine actual working values depending
on the concurrency or nonconcurrency of other steam loads for the drydock complex,
frequency of docking of maximum ship, and effect of multiple docking. High-pressure
steam for test operations is usually provided from portable generators.
Steam Mains. Provide graving docks with steam mains on both sides of
the dock. Size the pipe supplying the mains on each side to provide a carrying capacity
equivalent to that of the two dock mains. For example, two 152.4 mm (6 in) mains, one
on each side of the dock, require a supply pipe with a carrying capacity of two 152.4
mm (6 in) pipes, or an 203.2 mm (8 in) pipe. Base the determination of equal carrying
capacities on a table of equalization of pipes. Refer to MIL-HDBK-1003/8A, Exterior
Distribution of Steam, High Temperature Water, Chilled Water, Natural Gas and
Compressed Air. The number and location of steam branch outlets vary from three to
six on each side, depending on the size of drydock. Provide a suitable flanged valve
provided with a blind flange for each branch outlet. Size mains and branch outlets for
steam service, unless specifically directed otherwise, in accordance with the following:
Submarine and Destroyer Docks. For both single and double width
docks, use 101.6 mm (4 in) main and 63.5 mm (2-1/2 in) outlets.
Cruiser, Auxiliary and Carrier Docks. Size mains according to quantity
of steam carried and the permissible pressure drop. Outlets should be 63.5 mm (2-1/2
in.) Provide carrier docks with an additional 101.6 mm (4 in) outlet, located at the center
group of service outlets on each side of the dock, for feeding ships with 101.6 mm (4 in)
steam shore connections.
Piping. Steam piping must be in accordance with the provisions of MIL-
HDBK-1003/8 Exterior Distribution of Steam, High Temperature Water, Chilled Water,
Natural Gas and Compressed Air, concerning steam distribution systems. Condensate
return piping usually is not required, but should be provided when recovery of the
condensate is economically desirable or when dictated by special project requirements.