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 TB 740-97-4
bulletin. Detailed sealing requirements are outlined below.
(a) Engine exhaust. The engine exhausts at the stern of the craft will be closed with metal caps or plugs
which will be secured with pressure sensitive tape. The entire closure and adjacent area will be coated with strippable
coating and bituminous coating.
(b) Boiler exhaust. The boiler exhaust smoke pipe will be disassembled at the hinged joint and secured
on deck in the space provided for pipe storage. The stack will be secured in an inclined position to insure drainage. The
exhaust stub will be blanked with No. 18 galvanized sheet metal. The blank and adjacent areas of the stub will be
coated with strippable coating and bituminous coating.
(c) Vents, fire mains, fill and overflow lines. All vents, fire mains, fill and overflow lines opening into
areas within the zones being dehumidified will be sealed with strippable coating and bituminous coating. For covering
the vent screen in the aft cargo well bulkhead, a blank of No. 18 gage galvanized sheet metal will be applied, after which
the edges will be coated with strippable coating and bituminous coating.
(d) Doors, hatches, and manholes. All exterior doors, hatches and manholes leading into a dehumidified
zone, except those used for introduction of dehumidification piping, will be closed and sealed. Where hatch or manhole
cover fits over a raised coaming, bituminous coating will be troweled into the aperture between the closed cover and the
coaming. Flush type doors and covers will be sealed with strippable coating and bituminous coating. Recesses in covers
for opening devices will be masked with pressure sensitive tape and coated with strippable coating.
(e) Windows. If necessary, in order to provide the required tightness of the zones being dehumidified,
the edges of windows and portlights will be sealed with strippable coating and bituminous coating.
(f) Openings in forecastle deck. The openings in the forecastle deck for the ramp cables will be masked
with pressure-sensitive tape and sealed with strippable coating and bituminous coating. The coatings will be extended
over adjacent deck surfaces and also along the cables for at least 3 inches.
(g) Dehumidification piping system. The connecting points of all air tubing or ducts to areas being
dehumidified will be sealed with strippable coating and bituminous coating. The sealing will be carried over and around
flanges, adapters, and other devices used to attach or introduce the tubing or ducts. All joints and seams in the tubing
and ducts will be similarly sealed.
(h) Winch cover. A sheet metal cover will be installed over the entire winch. The cover will be
fabricated of minimum No. 18 gage galvanized sheet metal with suitable angle iron stiffeners. A coaming of 1 x 1/8-inch
angle iron will be tack welded to the deck around the winch. The angle irons will be positioned with one face against the
deck and the vertical face toward the winch. The size and shape of the coaming will be such that the sheet metal cover
fits snugly over the vertical faces. The sheet metal cover will be fastened to the coaming by No. 12 sheet metal screws
spaced approximately 3 feet apart. Openings for the air ducts specified hereinafter and for the sensing element will be
provided. Apertures between the coaming and the deck will be filled with bituminous coating. All joints and seams will
then be covered with strippable coating and bituminous coating.
(4) Dynamic dehumidification installation.
10,000 cubic foot capacity, 110volt alternating current, will be installed. The machines, with covers and stands fabricated
in accordance with figure 15, will be located generally as shown in figures 13 and 14.
(b)
Duct installation. Four inch diameter, No. 26 gage galvanized tubing with necessary ells, tees, reducing
fittings, and connections will be installed generally as shown on figure 13 and 14. Ductwork will be supported on 2 x 4-
inch wood stanchions. The ducts will be fastened to the stanchions by galvanized strapping.
1. Ducts to zone 1. To permit the introduction of air ducts to the compartments, the following
exterior doors will be removed and secured in the compartments, together with necessary hardware: the door to the
passage area aft of the ramp winch compartment on the port side; the door to the passage area directly opposite on the
starboard side; and the door to the storeroom on the starboard side. Blanks of No. 18 gage galvanized sheet metal with
flanged holes for attaching the air ducts, will be applied over the doorways. The blanks will be secured to the bulkhead
with clips riveted to the blanks, by tack welding at the corners, or by other suitable means. A dry air duct will be run from
the dehumidification machine and attached to the pipe which penetrates the bulkhead of the ramp winch compartment.
The pipe cap will be removed and stowed within the compartment. A branch
D-2
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