NATURE OF DEFECT
The 55” Caisson drain line suffered from protective coating breakdown. This resulted in multiple through wall perforations with further larger areas of scabbing and heavy substrate corrosion. The client requires a composite system repair solution to seal any existing through wall areas and minimise the risk of loss of containment until the caisson is replaced.
SOLUTION
Metalyte Pipeworks produced a repair method using Herculyte epoxies & engineered composites to seal the through wall defects with a minimum circumferential overwrap of 6 Layers of Cayman STD composite system. The Cayman STD system is ISO 24817 qualified and a water activated prepreg system that is used in subsea, splash zone and high humidity environments. This system has been selected due to the repair locations and environmental constraints.
REPAIR METHOD
Herculyte epoxies were fully mixed and inserted over the defect and the substrate was prepared (excluding the identified defect areas) using shot blasting to gain a surface profile to SA 2.5. Surface defects within the immediate repair area were repaired using Herculyte resins and 2 layers of Herculyte LV cloth was applied as a bonding coat to the entire repair area prior to application of the Cayman composite. Once the Herculyte LV was part cured, the repair area was wrapped in 6 Layers of Engineered Cayman-STD composite and allowed to cure until a minimum of 72 “Shore D” hardness was achieved.
