3X Engineering Subsea composite repair solution for pipe reinforcement

Overview

The goal of the repair, carried out in February 2026 by 3X ENGINEERING (3X) specialists was to strengthen a 12" riser affected by external corrosion defects: four through-wall defects and six metal loss areas. To restore the riser’s structural integrity, REINFORCEKiT® 4D SUBSEA was selected. This composite repair solution, designed for subsea application, was installed in two phases.

Scope of work

In accordance with ASME PCC-2 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 20 meters. Surface preparation was performed by sandblasting to achieve the required surface profile and ensure optimal adhesion between the riser and the composite repair system. The average roughness measured was 77 microns, far above the 60 microns required.

The composite wrapping repair was executed in four main stages, as detailed below:

1/ Primer Application. A dedicated subsea primer was applied to the prepared surface to ensure uniform coverage of the defective area.

2/ Plates installation with filler. Pre-manufactured metallic plates, sized to cover each defect, were coated with subsea filler and installed over the defective areas. The plates were secured using ratchet belts and maintained in position until full curing was achieved.

3/ Composite wrapping (Kevlar® tape + 3X subsea resin). The composite wrapping was carried out in two phases depending on the defect type.

Phase 1 - Through-wall defects ==> A total of 44 layers were applied over a 1200mm repair length to cover the four through-wall defects.

Phase 2 - Metal loss defects ==> This phase was divided into three wrapping sections to facilitate diving operations while maintening high application quality.

Wrapping 1 (localized above Phase 1 wrapping) covered 2 defects with 10 layers applied over a 780mm repair length.

Wrapping 2 (localized under Phase 1 wrapping) covered 1 defect with 10 layers applied over a 940mm repair length.

Wrapping 3 (localized under Phase 2 - wrapping 2) covered 3 defects with 10 layers applied over a 940mm repair length.

4/ Finalisation and validation. Identification plate was installed to ensure full traceability of the repair. Hardness testing was also performed to confirm complete curing of the composite system.

Results

This subsea repair successfully restored the structural integrity of the 12" riser despite significant through-wall and metal loss defects. Completed in shallow water under demanding conditions, the intervention met all quality requirements. The solution is designed to deliver a durable performance with an expected service life of 20 years.