METAL BODY REPAIR - OD1653 - LESSON 2/TASK 3
lead, with internal pipe threads, and soldered to the tank body.
c. Fiberglass Fuel Tanks. Fiberglass fuel tanks are constructed entirely
of fiberglass, except for the fittings or connections.
Because of their
light weight, durability, and seamless construction, they are used
frequently on armored personnel carriers and self-propelled artillery
(1) Their construction makes it possible to install them in irregular
spaces. They are used mainly in vehicles that are subject to vibration and
travel over rough terrain. Because of their irregular shapes, they do not
need baffle plates.
(2) Cell or bladder-type tanks are constructed of three layers of
synthetic material and a protective lacquer coating. They are similar to a
large balloon and are square or round in shape. They are sometimes used as
temporary or portable fuel cells and most units in the field use them for
fuel points. Their thick-wall construction provides an excellent shield for
foul weather or abuse. When not in use, they easily fold away for storage.
(3) The fuel compartment is not an independent section or a tank and
cannot be removed from the vehicle. It is constructed as an integral part
of the vehicle's hull. The composition and shape of the full compartment is
determined by the design of the parent vehicle.
Testing for Leaks.
Three methods are used to locate fuel tank leaks:
(1) Visible leaks are found by looking for stains left on the outside of
the tank. Seepage marks will be dark brown or dark red (depending on what
type of gas is used) stains on the tank. Cracks may be located by careful
observation of the tank.
(2) The best test is the underwater air test. The tank must be cleaned
prior to testing.
It is then made airtight by sealing the fluid gage
opening, the fuel filler pipe opening, and the drain plug, and then
attaching an air hose connected to the fuel outlet connection. Place the
tank in a vat or a canvas tank. Apply compressed