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TYPES OF ABOVEGROUND STEEL TANKS
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The type of foundation construction depends on size
and function of AST, bearing capacity of soil, level of underground
water, need of anchorage and possibility of owner.
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Tanks with double bottom.
They are
constructed on purpose to prevent the pollution on the soil when
one bottom is punctured.
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Tanks with double steel shell. They are applied when:
- the available area
is not very large and it is impossible to construct earth or
concrete
catching
basin;
- very expensive area, when it is cheaper to
construct second shell;
- in order
to decrease all kinds of outpouring and pollutions if there is leak in
the
shell.
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Tank with fixed roof.
They are applied when they store the products which are not volatile
and/or the tanks themselves have the small and medium sized volumes.
The roofs can be of the following kinds:
a) Self-supporting roof:
- cone roof - they are economical
when the volumes are up to 2 000 m3
- dome roof - they
are economical when the volumes are bigger than
2 000 m3. Steel dome roof could be applied when the
volumes are up to 70 000 m3 ( diameter D < 65 m ).
b) Supported
roof
- cone roof
– they can be applied in all existing volumes of the tanks;
- hanging
roof - they are still experimental.
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Tanks with floating roof.
They are applied when store volatile products and/or the tanks
themselves have big volumes, and the using of the fixed roof
increases the weight of the used material.
On the
other side the floating roofs are different types:
a) according to their position:
- external floating roof - when the tanks are open on
the top;
- internal floating roof - when
they are erected inside
in the
tank with fixed roof.
b) according to their construction:
- single deck floating roof;
- double deck floating roof.
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