Occasionally during inspection, caissons are found with significant defects, which threaten the immediate integrity of the caisson. When they reach this stage, they represent a considerable dropped object risk and may be beyond repair in a suitable timescale.
Usually the caisson can be restrained at one of the guides by ROV intervention, inserting a pin through the caisson wall, which prevents it falling after catastrophic failure occurs. In some instances, however, possibly due to geometry or location of the defect, it is not possible to employ this temporary method of retention and other solutions become a necessity.
CASA has developed bespoke retention tools as a provisional measure until such time that the defective section of caisson can be removed. The tools are deployed from topsides to eliminate diver intervention.
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