TYPICAL
DAMAGES OF ABOVEGROUND STEEL TANKS
During
their exploitation the above ground steel tanks bear unfavorable
influence of the environment and stored product. As a result their status becomes
worse and many damages
are collected into a
tank's structure. These damages can cause serious failures of the steel facility.
Referring
to this thesis the author visited many oil storage bases,
where he saw and evaluated the current damages of the tanks in the
exploitation.
The
correctness of one design decision could be better evaluated after
determined period of exploitation of the facility. Different
constructive solutions
taken during the years can cause different damages of the above ground
steel
tanks.
Damages on steel tanks, occuring during etheir xploitation, could ba classified as follow:
1.
Deviation of design geometric shape:
- local loss of stability;
- total (of whole tank) loss of stability;
- deviation to inside or outside of shell and / or bottom;
- movement and / or bending of annular bottom plates.
a) plane settlement:
- settlement of the whole bottom;
- settlement of the perimeter of tank.
b) irregular settlement:
- inclined tank;
- by the whole
bottom;
- by the perimeter of the tank;
- key on the floating roof with damages of antirotation device,
supports and equipment;
- tearing of supporting roof columns from the bottom.
2. Damage of
corrosion
- corrosion of welds;
- corrosion of steel structure.
a) the corrosion has regular distribution;
b) local corrosion.
Pictures
below show typical
damages that could be met in aboveground steel tanks in service
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