15

various conditions proves the future of these tanks.
The use of oil for fuel has a’ready been adopted
by many plants, and others, as soon as they realize
the economy, will change from coal to oil. This
again opens the question of storage. Concrete tanks
have been successfully used many years for stor-
ing oils of
every grade, crude, fuel, gasoline, kero-
sene, benzine, etc. At the
present time there are
over 850,000,000 gallons of fuel oil storage capacity
in the form of concrete tanks.
Among the cotton oil companies using them are
the Joyton Cotton Oil Co., Joyton, Texas; Winters
Cotton Oil C0. ,: Winters, Texas; Seymour Cotton
Oil Co., Seymour, Texas; Anadarko Cotton O'l Co.,
Anadarko. Okla.
Underground concrete tanks mean greater con-
servation. They reduce evaporation losses to a min-
imum by keeping the oil at a fairly even
temper-
ature; leakage losses are stopped entirely in a good
concrete tank. By being below ground all yard
space
is available for the storage of materials. In-
surance rates on concrete tanks in some states are
considerably lower than on other types of contain-
ers; concret tanks do not raise the rates on sur-
rounding buildings.
Every concrete tank, whatever be the shape,
capacity or use, is a subject for special design. Un-
less concrete tanks are properly designed to with-
stand pressure of the contents and from without
when the tank is empty, small cracks
may open up
and the contents may leak through or the tank may
fail completely. This is not peculiar to the concrete
tank alone, but is true of all tanks improperly
designed, regardless of the construction material.
With a proper design the success of a concrete
tank depends upon
the choice of materials, proper
proportioning, mixing and lac'ng of the concrete and
protecting the finished work until the concrete has
properly hardened. Neglect of any one of these
points may be cause for dissatisfa-ction later. The
concrete should be so proportioned as to secure a
dense, compact mass; this can usually be obtained
with the
proportions of one sack of portland cement,
two cubic feet of sand and three cubic feet of peb-
bles or broken stone. Consistency, or the amount
of water used in mixing the concrete, plays an im-
portant part, as either too much or too little may
leave pockets in the hardened concrete. Mixing of
materials should preferably be done in a mechanical
batch mixer so that mixing may
be thorough and
uniform and that the placing of the concrete may be
rapid and with as few interruptions as possible.
The best results would be obtained by building the
tank in one operation, but as this is usually impos-
sible, the work should be speeded up so as to reduce
construction joints or seams to a minimum. When
it is
necessary
to
stop concreting, precautions, must
be taken to join new work to old by roughening
and washing the hardened concrete and flushing it
with mortar immediately before placing the new
concrete. Uusally a wedge shaped 2by 4, small end
down, is embedded in the old concrete so that a
key is formed. It has also been found of further
advantage to embed a metal plate in the old con-
crete so that it will extend into the new.
The treatment of the interior surface depends
upon
the character of the liquid to be stored. Fore-
going examples of cottonseed oil tanks show that
for such use a rich mortar coat, applied immediate-
ly after the forms have been removed, has been suffi
client. It is probable that a further treatment with
sodium silicate (water glass) or magnesium fluosil-
icate would be of benefit. These methods have been
successfully used on tanks used for storing fuel
oil heavier than 30 degrees Baume, although special
commercial coatings have sometimes been used. J*or
the storage of oils lighter than 30 degrees Bauyxuß,
some special coat : ng
is needed to prevent the pene-
tration of the oil.
A view of a packing plant where cottonseed oil is taken from the large tanks. Concrete enters largely in construc-
tion of these tanks.
15
TH E CON C R E 'l' E A( i E
October, 1920.