Tank storage equipment

Is the tank completely round or slightly deformed?

Apart from the question if the tank is completely round or slightly deformed, it is important to know whether the tank wall is an 'overlap' construction or has an even surface.

Start-up project


A suitable floating roof seal for a tank shell with an overlap construction, allows the seal to move up and down the tank wall without the risk of snagging at the overlaps on the tank wall.


In order to ensure that the floating roof seal is fully sealed against the surface of the tank wall, preventing leakage or rainwater and snow into the tank, it is very important to know whether the tank is completely round or has some kind of deformation.

Measurement of the rim space, i.e. the distance between the tank wall and the floating roof

If the cistern is deformed, an accurate measurement is required. The results of the measurement will give an indication of which type of seal is most suitable, as well as the size of the seal and the springs against the wall.

The measurement is carried out as follows:

  1. Add the distance between the tank wall and the floating roof at two opposite points (A1+A2, B1+B2, C1+C2, etc) to obtain the maximum possible distance at each point. Measurements should preferably be taken every <3 metres around the entire surface of the tank shell.
  2. Repeat the above measurement procedure for different flotation levels.

Example of a summarised measurement result:

Centring of the floating roof

For the sealing system to be effective and have a long service life, the floating roof needs to be as centred as possible. This is achieved by using sealing systems with a well-designed and high quality spring design, which Imhof Tank-Technik supplies.

Read more in detail about floating roof measuring and centring