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 compound on approximately 30 square feet of area. Allow the material to penetrate into the preservative
film for about 5 minutes. If the cleaner appears to be drying, reapply a small amount. Rinse the surface
with a stream of hot water at about 90 to 100 pounds pressure. Naphtha-rosin-soap mixtures have a
flashpoint of 40.6 C (105 F) and its use requires fire precautions equivalent to those observed when
spray painting.
b. Methylene Chloride (Dichlord-Methane) Paint Remover. The use of methylene chloride-type paint
removers, containing a minimum of 70 percent by weight methylene chloride, followed by steaming, has
been found effective for removing thin-film rust-preventive compounds, especially if the mixture has been
applied over paint.
(1) Brush the cleaning compound liberally on the preventive-coated surface. Allow the material to
penetrate into the preservative film for about 15 minutes. If the cleaner appears to be drying, reapply.
Direct a jet of steam to the area to be cleaned, holding the gun top 1 to 2 inches from the surface. The
steam gun should have a 1/2-inch nozzle (approximately).
(2) If any preservative compounds or loose paint remain, brush more cleaning material onto the
surface, allow it to soak again for 15 minutes, and steam the area. In extreme cases, this cycle may have
to be repeated once more.
a. Hand Cleaning Use. The hand-cleaning method is used solely to prepare bilge surfaces for
repainting, as some routine methods of cleaning bilges for other purposes are inadequate for paint
preparation. Follow precautions described in paragraph 3-8.
b. Hand-Cleaning Procedures. When hand-cleaning procedures are implemented work sections no
larger than 200 to 300 square feet should be cleaned at a time. Longitudinal and transverse structural
members may be used as boundaries to define the work sections. Clean and prime each section before
starting work on the next section. The procedure is essentially hand cleaning, with the assistance of
detergent solutions to aid in soil removal
surface for recoating, the cleaning methods described in this paragraph must be used, depending upon
the conditions to which the inorganic zinc coating has been subjected. If the inorganic zinc has had heavy
traffic and physical wear, or if the existing top coating has been worn away to the inorganic zinc, the zinc-
coating should be thoroughly scrubbed with a cleaning solution prepared by mixing 8 pounds of sodium
metasilicate and 1 gallon of detergent with sufficient water to make 30 gallons of solution. Flush the
cleaned surface with fresh water to remove loosened grime and cleaning solution and allow to dry. Lightly
roughen the surface either by mechanical means or by abrasive brush blasting.
for gas freeing, safety, and oxygen sufficiency. Install explosion-proof ventilation equipment and ventilate
tank.
a. Tank Interior Cleaning. Install fresh water hose lines. Ensure that the hoses extend to the tank
bottom, continue ventilation, enter tank, and wash down all interior surfaces with a high-velocity stream of
freshwater. Remove the sludge to the sludge tank and muck out as necessary. Ventilate to dry tank
surfaces. Remove residual water and oil from the tank bottom.
(1) Portable tank cleaning machines are readily available from the commercial industry. They use a
rotating nozzle and a high-pressure stream of water to remove sludge, rust, loose paint, and scale.
Normally they are used to clean cargo tanks on larger vessels.
(2) Using non-sparking power tools (or hand scrapers if power tools are unavailable), remove all
adhering sludge or deposits, rust, loose mill scale, and loose paint. Tightly adhering paint may be retained
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