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C) technological process

It is necessary to measure the speed of filling/emptying. When we do not consider this speed and it do not correspond to the erected technological facilities it is possible damage and even destroying of the roof.
In order to fix the floating roof according to its designed position (for avoiding its rotation), the antirotation devices must be put inside in the tank, parallel to the shell.
In the past the number of antirotation devices usually was two per tank. Now during the repairing works one of the antirotation devices can be removed and only one antirotation device can left. It must be done in order to neutralize of the inclinations of the autorotation devices from their designed position during the erections and during the exploitation. When the antirotation devices are not vertical it is possible to key of the floating roof with all consequences connected with it. It is necessary that the anti-rotation device supports all horizontal efforts which were supported before by two devices.

3. Constructive requirements
a) approximately 200 mm free space must have between external floating roofs and the shell, where the seal will be mounted. The modern seals assure good jam and normal work when the distance between shell and roof is from 100 to 300 mm;
b) minimal thickness of the steels in the pontoons in the membrane is 5mm (t_r ≥ 5 mm);
c) the maximal distance between the roof supports of the floating roof must not be bigger than 1000 x t_r (thickness of the membrane);
d) distance from roof supports to welding joint in the membrane is not smaller than 300 mm;
e) when there are the girders stiffening the membrane, roof supports must be put in the area in this stiffening.
f) the length of the supports is deferent depending on its status:
- during the exploitation – minimal height must grant the tank filling without the liquid jet to touch the vertical board. It is unacceptable that the floating roof in its lowest position to lie upon the technological facilities;
- during the repairing works on the tank - the minimal distance depends on considerations for easy doing of the repairing works. It is assumed to be 1800 mm in the lowest point of the roof.
g) the floating roof, stepped through its supporting constructions on the bottom or when floats on the liquid must have the slope toward the roof drain not less than 1:100. For insider roofs this slope have not be considered;
h) upon the floating roofs must be constructed foam dam which height must not be less than 300 mm at 1 m from shell of the tank;

i) for fixing the roof according to the design conditions the antirotation devices must be considered. They do not allow the rotation of the roof. They must bear the horizontal forces, caused by the rolling ladder, by the uneven load from snow, by wind and by rotation of the stored product when it is mixed or the tank fills;
j) the drain pipe must have the diameter not smaller than 3” for the tank which have the diameter D ≤ 36 m. The drain pipe must have the diameter not smaller than 4” for the tanks which have the diameter D > 36 m;
k) the pontoons situated on the periphery must be separated by waterproofed barriers and every pontoon must have manhole for inspection;

l) in the central part of the roof must have one manhole for inspection, through which people can go to the roof when the roof is in its lower position and the tank is empty.