Bituminous composition. -
Preparation of surface. - The preparation of a surface for bituminous
composition shall not be started until it is certain that no other work will
be under way in or over the bilge or compartment to be coated, and that no
water or grease, or oil will be drained into the compartment. In
applying bituminous compositions, it is absolutely essential that the surfaces
to be covered are thoroughly dry and cleaned down to bare metal. The
utmost care shall be exercised to insure that the surfaces are entirely
cleaned of all rust, grease, scale, or paint. The metal shall be cleaned
bright by sandpapering, sandblasting, or other approved means. Where the
surface is pitted, it may be brushed hard with a fine steel wire brush, such
as is used preparatory to galvanizing or nickel plating, or by other approved
means, to insure that the bottom of pits are made as clean and bright as the
smooth surface of the plate. All dust shall be removed just prior to
applying the bituminous primer (solution).
Temperature. - In cold weather it may be
necessary, in order to avoid having damp or minutely frosted surfaces, to blow
heated air to insure satisfactory contact of the bituminous primer (solution).
Heating. - Bituminous enamel shall be heated
in pots provided with thermometers, and temperatures shall be regulated
within limits specified by the manufacturers of the enamel.
Application. - The bituminous primer
(solution) shall be applied as soon as practicable after the structure has
been cleaned and made ready. It shall be well spread with a brush, and
care shall be taken to insure that no spots are left uncovered. After
the primer has dried, or at least become tacky, it shall be followed by a coat
of bituminous enamel, applied hot. In any case, bituminous enamel shall
be applied within 24 hours after the primer is applied. Long drying
periods result in lack of adhesion of the enamel.
The enamel shall be applied to the lower surfaces
first, as it has been found that in coating the upper surfaces first,
drippings and streamers there from cause difficulty in the proper coating of
the lower surfaces. It shall be applied with a brush to a minimum
thickness of 1/16th inch. For flat horizontal surfaces the enamel shall
be spread rapidly with a brush or some equally efficient means to a minimum
thickness of 1/8th inch, except in continuously wet bilges and sumps where
thickness shall be 1/4 inch.
The enamel shall be applied along the lower edge of
the bulkhead bounding angles, boiler and machinery foundations, and other
metal work projecting through the enamel, in order to completely coat the
As the primer (solution) and enamel are both black,
it is difficult to see where the enamel has been applied. Special care
is necessary, therefore, to insure that the entire surface is coated with
The applied film of bituminous primer (solution)
shall be perfectly clean and free from all grease, dirt, oil, moisture, etc.,
before applying the enamel.
Bituminous solution is intended only as a bond
between the enamel and the metal surface. It is not a protective coating
and therefore shall not be used as such.
Plastic compositions for tanks. - The material
is broken up by sledges into pieces whose largest dimension should not be over
6 inches. The broken material is melted in steam-heated or gas fired
reducing kettles (standard hot plastic reducing kettles) and raised to a temperature
of 400 degrees F. The reducing kettle should be as close as possible to
the place of application to avoid heat losses in transferring material.
When it is inconvenient or impossible to place the reducing kettle in the
bottom of the drydock near the work, a 10-gallon "holding
kettle" is used to maintain a supply of material at 400 degrees F.
within a few feet of the tank openings.
The material at 400 degrees F. is drawn off as needed
into insulated gallon paint pots and is immediately handed into the tank for
application. Ordinarily between 1/2 and 3/4 of a gallon of melted
material is placed in each pot. The amount should be regulated so that
all the material in the pot can be brushed out before the temperature drops
below 300 degrees F. Under average conditions the material will maintain
sufficient heat for 20 minutes if an insulated pot is used. A standard
one gallon paint pot is satisfactory. This pot is slipped into a
detachable asbestos lagged shell which clamps onto the bail supports of the
A standard 2 1/2 inch brush has been found to the the
most efficient for a brush application. The brush should not be dipped
over 2 inches into the melted material. If too much paint is taken on
the brush it will be difficult to brush it out to a thin, even layer before it
hardens. All work should be carefully for pinholes and holidays as the
work progresses. A coating between 1/32nd and 1/50th inch is considered
ideal and is easily attained if the material is applied correctly and at a
temperature above 300 degrees F. A coating of this thickness weighs
between 0.135 and .25 pounds per square foot.
Material can also be applied by spraying with the
standard equipment used for the application of hot plastic antifouling
paint. All bulkheads and large flat areas are easily coated with the hot
spray. The smaller areas such as stiffeners, I beams, etc., cannot be
sprayed very well with this equipment and are best touched up by brush after
the larger areas have been coated. Any pinholes in the sprayed areas are
also touched up with a brush at this time. The spray job gives a
slightly heavier film than a good brush application but the increase in weight
is not considered excessive in view of the saving of time and labor.
Portland Cement. -
Applications. - No cement shall be applied until compartments are
completed and tested satisfactorily for tightness. Wherever cement is
proposed for use on iron or steel, the extent, location, and details of the
installation shall be referred to the Bureau for approval.
Uses. - Cement shall be used only for the
Continuous or with tiling in areas around water
drains. It shall be applied over bituminous enamel and slope toward the
drain. the total thickness shall not exceed 1 3/4 inches.
On a specific approval and to a minimum thickness for
filling pockets or crevices.
Where ceramic tiling is provided as a deck covering,
the deck plating shall be stiffened where necessary for plating under 10.2
pounds on 4-foot beam spacing. The method and order of application shall
be as follows:
Bituminous coat, primer and enamel; 3/4 inch thick.
Concrete, 1 part Portland cement, 2 parts Haydite
or equivalent; 3/4 inch thick.
Float coat for tile, 1 part Portland cement, 1 part
sand; 1/2 inch thick Tile, 1/4 inch thick.
Total thickness shall not exceed 1 3/4 inches
except as required for drainage.
In applying the base for the tile, the deck plating
shall first be thoroughly cleaned, the bituminous primer shall then be applied
cold, followed by the enamel, applied hot, then another coat of primer with
dry Portland cement scattered over the surface while wet. The concrete
shall then be applied, followed with the float coat and tile.
All metal blocks and stools for fastenings in way of
tiling shall be welded to the deck or secured by at least tow fastenings
before the cement is laid.
Gutters and floor drains shall be fitted as
required. Tiling shall in all cases slope toward the drain and in
addition shall slope locally away from the bulkheads and fittings to prevent
water standing against the metal. Fillet tile shall be used at bulkheads
and coamings, except where the bulkhead stiffening renders this impracticable.
Quality. - Cement used on vessels shall be of
a light weight grade preferably one developing high early strength.
Cement shall be mixed with siliceous sand which shall consist of a well graded
mixture of course and fine grains, with the coarse grains predominating.
Not more than 30 percent shall pass a No. 50 sieve. It shall be free
from clay, loam, mud, salt, alkali, organic matter, or other impurities, and
particles not passing a 1/4 inch mesh screen, unless, in the opinion of the
officer-in-charge, the proportion of particles above 1/4 inch is so small that
the sand will perform its functions in the concrete without screening.
Sand for concrete shall contain not more than 5 percent of silt when measured
by volume by shaking a sample of the material with water and allowing it to
Crusher screenings passing a 1/4 inch mesh screen may
be combined with and measured as sand, but not more than 1/3 of the same
in any one batch shall be of this material, unless it can be shown that the
sizes of the particles are practically in the same proportion as in the most
suitable grades of natural sand.
Mixing. - In mixing Portland cement (except
for setting tiling and except where used as deck covering) 1 part of cement
and 2 parts of sand shall be used for the filling coat. This shall be
mixed in small quantities to prevent setting prior to application, and in
general, shall be mixed with the least amount of water that will permit a
proper consistency for working.
Curing. - The necessary curing after the
cement has set shall be done by keeping the work moist from about 2 to 10 days
depending upon the type of Portland cement used, early strength requiring less
Testing. - All cement shall be carefully
tested to ascertain whether it has properly adhered to the metal and, where
not found to adhere, the contractors will be required to remove the old cement
and apply new cement until such adherence is obtained.
Rust Preventive Compound. - Rust preventive
compound shall be applied so that the thickness does not exceed 1/16th
inch. Where the thickness after application exceeds 1/16th inch, the
excess thickness shall be scrapped off.