Nature of defect
Initially the 24” Caisson had suffered a through wall leaking defect at the top location just under the bottom deck. This was due to active external corrosion resulting in long term wall loss. After further inspection, it was evident that the Caisson had corroded in several other locations to an extent where other through wall leaks had appeared. The client also required an additional clamp support to be installed further down on the Caisson, however this would be located at a corroded section of the pipe.
Solution
Metalyte Pipeworks solution was to address these issues individually in a sequence that would get the full scope completed in the safest and most productive manner. The Caisson could not be isolated so all leaks were sealed live. These locations were then reinforced with a composite wrap. A design was put together to calculate the composite requirements for the clamp location. The composite was required to strengthen the Caisson and also to withstand the clamping force of the clamp.
Repair method
The Metalyte Pipeworks technicians began working from the top of the Caisson where the largest leak was located. The defect measured approximately 150mm circular. The pipe surface surrounding the defect was mechanically prepared before the technicians installed a bespoke, cold bonded repair incorporated with injection ports. This was wrapped in using the Titan 505 live leak system, which was then injected to seal the leak. Once the leak was sealed, the repair area was wrapped in 6 layers of Dragon composite landing on to the box section on the underside of the deck.
