METAL BODY REPAIR - OD1653 - LESSON 2/TASK 3
(3) The live steam and the exhaustandair methods are used mainly for
terneplate tanks, but they can also be used on fuel compartments. The
waterfilled method is another means of cleaning fuel tanks. After locating
a leak, fill the tank completely with clear water and replace the fuel cap.
Then turn the tank until the leak is in the topmost position and repair with
a soldering iron only. For fiberglass and celltype tanks, a plain water
flush is the best method of cleaning.
(4) Patching. Before patching a damaged tank, first remove it from the
vehicle and remove all vapors. The area to be patched must be cleaned and
tinned at least two inches beyond the crack in all directions. When cutting
a patch, use galvanized metal large enough to extend beyond the crack at
least 1 inch in all directions. Round all corners and tin the metal on the
side that is to make contact with the tank. Place the patch on the tank and
sweat solder together. The last step is to test with five psi air pressure.
(5) Safety Rules. Safety rules for fuel tank repair should be strictly
(a) Do not depend on your eyes or nose to decide if it is safe to put
an open flame on a fuel tank; steam it first. A very small amount of
residual gasoline or other explosive liquid can cause a serious explosion.
(b) Never use oxygen to ventilate a fuel tank.
(c) Never place a lighted torch or flame of any kind in the fuel tank
opening to test for vapors after it has been cleaned.
tank when the exhaust method has been used to remove fuel vapors.
(e) Never use an oxyacetylene torch to remove tops of 55 gallon
drums. Always use a hammer and cold chisel. All types of 55 gallon drums
should be cleaned before removing the tops. Vapors of some liquids will
explode upon the first spark. Since cold chisels are made of steel, a spark
could very easily be struck. With priority on safety, only drums which
contain known nontoxic substances should be used.