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 During manual disconnection of a stiff or frozen hose, a truck should
be used to provide the force needed to retrieve the hose. Persons handling
hoses then could concentrate on guiding the hoses and avoiding slipping on
ice/snow covered piers.
13.4 PASSIVE FREEZE PROTECTION. Wherever possible, the use of passive
techniques to prevent sewage hoses from freezing should be implemented.
Passive techniques require minimal additional materials and provide very
good protection in most freezing temperature exposures. The use of passive
techniques is recommended especially for ships that do not require long-term
hookups, and in ports not usually subject to prolonged periods of very cold
temperatures, below about -18C (0F).
13.4.1 HOSE RIGGING. Hoses rigged with a continual downward slope towards
the discharge end, with essentially no catenary, will be able to drain com-
pletely, thereby eliminating standing water that could freeze. No addi-
tional materials, except for spring lines in some cases, are required for
this type of rigging. However, the use of nonstandard hose lengths, unusual
routing between the ship and shore, and a pier connection that is not the
nearest to the ship's discharge connection may be needed. The special rig-
ging requires additional labor and time. The technique may not serve in
ports having high tidal fluctuations, and is not applicable when a ship's
connection is below the level of the shore connection (e.g., submarines).
13.4.2 PERIODIC SHIP PUMP-OUT. This technique is effective regardless of
the method of hose rigging or relative position of hose connections.
Sufficiently frequent pumping of a ship's relatively warm wastewater through
sewage hoses will prevent the hoses from freezing. Personal dialogue with
cognizant responsible ship personnel> supplemented by a written request/
notice is recommended to obtain positive assurance that minimum pumping
requirements will be met, especially during late night hours, when both
ambient temperatures and normal CHT pump-outs are usually minimal. Two
methods to be considered are: 1) manual operation of CHT pumps for a stated
time, such as 1 to 3 minutes on a regular, set time schedule; and, 2) the
use of constant CHT tank influents, such as minimum tank washdowns or the
use of garbage grinder eductor to assure sufficient wastewater volume
requiring pump-out. For the 4-inch noncollapsible hoses, the required pump-
ing frequency ranges from at least once every 4 hours for ambient tempera-
tures down to -7 C (20 F) to at least once every hour for temperatures
down to -18 c (0 F); more frequent pump-out is beneficial. For the
smaller, submarine sewage hoses, the pumping frequency must be increased.
This procedure requires protection such as insulation for hose ends and
exposed ship and shore connection fittings, because the metal segments of
the entire ship-to-shore hose hookup are more prone to freezing.
13.4.3 HOSE INSULATION. Insulation, such as flexible polyurethane closed-
cell foam, can provide significant freeze protection when properly installed
and maintained in good condition. There are insufficient data from field
trials to present complete information for its use on all types and sizes of
sewage hoses currently in use under all specific temperatures. However,
based on limited field tests, insulation should be considered for use in
freezing temperatures down to about -18 C (0F), and for very long
term hookups, which may occur with tender ships or housing barges. Uncovered
13-2
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