Nature of defect
The 30” Crude oil line had suffered from (CUI) external corrosion. This has resulted in an axial through-wall defect at the 6 o’clock position. After further inspection, an additional defect was found measuring 800mm long. This other defect was not through wall and was treated as a separate repair resulting with the line having two separate repairs next to each other. The client required a composite repair to seal the leak locations, build up the wall loss and to bring the line back up to its full design specification. The 24” line adjacent to the 30” had also suffered from (CUI) external corrosion. Inspection had found extensive wall loss. The client required a composite repair to rebuild the corroded areas and to bring the line back up to its full design specification at the same time as the 30” repair.
Repair method
Metalyte Pipeworks produced a repair method to seal the leak on the 30” through wall line with a minimum overwrap of 22 layers of Dragon Q-STD, repair the wall loss on the 30” line with a minimum overwrap of 12 layers of Dragon Q-STD and then 10 layers of Cayman STD composite system for the 24” line respectively.
