Cylindrical steel tanks



Types of steel tanks

Stiffening of membrane of single deck floating roof

Methods of erection

Typical damages of aboveground steel tanks

Inspection of steel tanks

Realized projects of tanks

Typical drawings of tanks


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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;
through putting of additional pontoons