Advantages:
- because pending of the
membrane is increased it is stretched;
- because slope of the roof from loading is increased in the center the drain of the poured above
water is better;
- the movements and vibrations caused by the
wind are considerable decreased;
- the number of the welding joints is smaller
in comparison with the stiffening girders.
Disadvantages:
- the pontoon in the center of the roof coincides
or is close to the drain system. It is necessary to have more
complicated and
labor consumption detail for assuring of properly drain of the water:
- the level of sink of the floating roof is
increased;
- the efforts in the roof membrane, pontoons and
supports are increased:
- it is possible that the membrane swells between
the periphery and the supports as a
balloon, if it is not complementary stiffened with ribs;
Setting of
many pontoons evenly
upon the membrane
Many pontoons upon the membrane (The Hendrix Group)
Advantages:
- membrane is stretched because of the
increased loading respectively pending
of the membrane;
- the drain of the water fallen there is
improved;
- the vibrations and movements caused by wind
are decreased;
- the loading of the pontoons is even upon the
whole membrane which does not allow the swelling of the liquid steam as
a
balloon.
Disadvantages:
- the level of sink of the roof is increased;
- the efforts in membrane of the roof, in the
pontoons and in supports are increased;
- the number of the weld joints is increased;
- the consumption of the metal is increased compared
to one pontoon in the center of the membrane.
On
the point of view of the exploitation this solution is good, and the
deviation of the membrane from its project shape are decreased.
