Centring of Floating Roof
Proper sealing of a floating roof rim space as well as the general life expectance of a sealing system are based on adequate and sufficient centring of the floating roof.
Foam filled primary seals and spring loaded seals can offer sufficient centring forces. Liquid filled seals provide little centring forces and require perfect tank roundness.
The centring characteristic and the specific centring forces of a certain sealing system can be described by comparing the compression forces existing at two diametrical points of the floating roof, as shown in the following diagram. Sealing systems with good centring characteristic show progressive increase of sealing forces when the rim space is reduced.
Diagram of Centring Forces