TM 55-203
being done. The tank head must never be heated to a
b. Leaking Tanks. A leaking tank car should
bright red heat, as this will cause the member to buckle.
have its load transferred as soon as possible; if leaking
When straightening tank heads, never strike the head
badly, temporary repairs must be accomplished. One
directly, as that will mar the sheet or member It is
method is to stuff waste or rags, impregnated with a
preferable to use a flat-faced swage or wooden maul
heavy lubricant into the opening to arrest the flow.
against the surface. If the tank head is badly staved in,
Where the rupture is not too great, soap or clay may be
it can be straightened by means of a jack placed
adequate. These are strictly temporary expedients, only
between timbers and braced against the other end of the
performed to provide time to transfer the lading to
car. While it is frequently possible to straighten dents in
another car. If possible, the empty tank car selected to
tank heads and shells without removing the tank from
receive the transferred lading should have held a similar
the car frame, more ,extensive damage requires
commodity. Otherwise the lading may be contaminated
removal. The tank should then be set up on skids or
or two noncompatible substances become mixed. If
large horses for repairs.
possible, the load should be transferred by gravity flow.
If a gravity transfer cannot be made, siphon or pressure
e. Shell Plates. The repair or straightening of
may be used. Air pressure should be Judiciously used
dented shell plates generally is performed in the same
and only on cars loaded with heavy oils, and at a very
manner as repairs to tank heads, discussed in d, above.
low level Leaks in seams can be calked temporarily by
packing them with twine or lead-wood pushed into place
When it is necessary to remove a tank plate, care must
with a sharpened piece of wood or bronze After the
be taken to avoid damaging it when removing the old
twine calking has been tamped into place, soap should
rivets. Rivets should be driven (headed over) on the
be patted over it to form a ridge. Tools made of ferrous
outside and bucked on the inside, using a well designed
metals must not be used in tank car repairs of this type,
bucking bar instead of another hammer. Rivets must be
since there is a danger of igniting flammable lading or
tight. A loose rivet can be detected by holding a finger
gases by sparks that might occur when ferrous metals
on the rivet head and tapping the rivet lightly with a
are brought into sharp contact. A dent in a tank car
hammer. If loose, it will vibrate slightly. Loose rivets
does not require any attention if not leaking.
must never be calked. If they leak, they must be
replaced.
c. Outlet Valve Leaks. Many leaks occur at the
f. Safety Valves and Vents. The lading often runs
outlet valve underneath the tank. These generally are
caused by a leaking valve inside the tank. This type of
into the top of the safety valve when the car is being
leak often may be stopped by tightening the cap on the
loaded. Asphalt or similar products may congeal and
bottom of the tank nozzle. If this does not remedy the
prevent the valve from unseating at the prescribed
trouble, a blind gasket can be placed over the end of the
pressure. If inspection indicates a faulty safety valve,
tank nozzle and the cap screwed up tight against it.
remove the valve from the tank. To disassemble a
Sometimes such leakage can be stopped by removing
standard safety valve, remove the valve plug from the
the dome cover and moving the valve up and down
center of the valve. Back out the valve stem until the
several times. Bad leaks often develop in the tank
spring follower and spring are detached. Remove the
nozzle of the outlet valve, because of freezing in cold
valve and valve stem from the housing and inspect the
weather. As water is heavier than oil, any formed from
valve. If the valve or valve seat is pitted or rough, the
condensation will be at the bottom of the tank and be
contact surfaces may be ground smooth with emery
first to run out. This water often freezes in cold weather,
powder. All parts of the valve should be cleaned before
bursting the tank nozzle, and causing a leak when it
reassembly. Spring tension will be adjusted and the
thaws. In such cases, the leaky valve should be
reassembled valve tested for correct pressure opening.
replaced after the car is emptied and before reloading.
g.
Dome Covers.
Dome covers require little
d. Tank Heads. These members, the ends of the
maintenance, as they seldom fall in service. Dome
tank shell, are frequently bent. This results from being
covers are provided with 1/2-inch holes just underneath
struck by the shifting load of another car or as a result of
the
flange
of
the
cover.
These
holes
a blow from a projecting object or building. Such dents
may be straightened by bumping them from the inside
with a heavy maul or a tool made from an old axle. To
facilitate this operation, a little heat may be applied to
the dented areas of the tank head while the bumping is
9-15
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