STIFFENING OF MEMBRANE OF SINGLE DECK ROOF
The
complementary
stiffening of the membrane is required to be continuously ensured that
it be in design condition, without big deviations from:
a) wind blows - when the tanks are with big diameter D, wind could provokes waves on the
membrane lake a lake. These serious displacements lead to fatigue
destruction on the welds in membrane;
b) vapors of storage products - with increasing of temperature of the
stored product vapor pressure becomes to be higher. It could be bigger
than self-weight of the sheets. As a result the membrane gets new shape
and it is like a balloon. It is obstacle to free roof drain;
c) erection with mistakes - by the mounting of floating roof, the
membrane could be putted with deviations from project flat shape. This new
condition is obstacle to free drain of the roof. As a result, retention water speed up corrosion. Most
of tanks with floating roof in Bulgaria are with membrane, which is
made of rolls. After unfolding of rolls, membrane continues to be wavy.
Additional stiffening of membrane could be applied for external floating
roofs where ambient conditions are worse than conditions for internal
floating roofs.
Stiffening of the membrane should be executed when:
- the diameter of the roof D
is bigger than 40,0 m;
- the stored product inside has serious evaporation;
- the product has been stored by increased temperature;
- snow loads are extreme height;
- wind loads are severe.
The
complementary
stiffening of the membrane
can be done in two ways:
a) through
putting of additional
stiffening girders on the
membrane;
b)
through
putting of additional
pontoons
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