Subsea composite repair solution for pipe reinforcement

Overview

The objective of the repair, carried out in January 2026 by the local distributor of 3X ENGINEERING (3X) was to reinforce a 12" oil pipeline section, with an operating temperature of 50°C, located on a CALM buoy within Australian waters that was affected by external corrosion. To restore the structural integrity of the pipe, 3X composite repair solution specifically designed for subsea environment, REINFORCEKiT® 4D SUBSEA, was selected and installed.

Scope of work

In accordance with ISO 24.817 standard and 3X design calculations, REINFORCEKiT® 4D SUBSEA system, using a dedicated subsea resin, was selected as composite repair solution. The repair was performed in shallow water at a depth of 3.3 meters.

Defect area overview

Surface preparation was performed by sandblasting to achieve the required surface profile (minimum Rz 60 microns) ensuring optimal adhesion between the steel pipe and the composite repair system. The surface was thoroughly cleaned prior to composite application.

Surface preparation completed

The composite wrapping repair was executed following 4 main stages, as below:

1. PRIMER APPLICATION. A dedicated subsea primer was manually applied to the prepared surface using slow circular movements to ensure uniform coverage of the defective area.

2. PLATE INSTALLATION WITH FILLER. A pre-manufactured metallic plate, conformed to match the pipe shape, was coated with subsea filler and immediately centered over the defect. The plate was secured using ratchet belts and maintained in position until full curing.

3. COMPOSITE WRAPPING. Kevlar® tape impregnated with 3X subsea resin was wrapped helicoidally around the pipe. The subsea wrapping operation was performed by a team of 4 qualified divers under the supervision of a 3X specialist ==> A total of 14 composite layers were installed over a repair length of 128mm, in accordance with the approved design calculations.

Wrapping completed

4. FINALISATION AND VALIDATION. Upon completion, final inspection and quality control were conducted. An identification plate was installed to ensure full traceability of the repair. Hardness testing was performed to confirm proper curing of the applied materials.

Results

The entire scope was successfully executed within a single day, with zero incidents or safety deviations. The structural integrity of the pipeline has been fully restored, extending its service life by an additional 20 years. This project stands as a strong demonstration of the performance and reliability of advanced composite wrap technology, combined with effective cross-functional collaboration, meticulous planning, and precise execution in subsea integrity management.