Subsea composite repair solution for pipe reinforcement in the Middle East

Overview

The objective of the repair, carried out in May 2024 by 3X ENGINEERING (3X) and its local distributor was to reinforce a 24" gas pipeline suffering from 8 external impact defects. Four dents are situated on the topside and 4 other dents on the bottom side of the pipe. To restore pipe integrity, it was decided to repair the defected areas using 3X composite repair solution specifically dedicated for subsea environment REINFORCEKiT® 4D SUBSEA.

Scope of Work

All dents were modeled at the same time to consider the interaction between them. The geometry was
previously reconstructed using FEA study. According to ISO 24.817 standard and 3X calculations, it was decided to apply REINFORCEKiT® 4D SUBSEA using R3X65S resin. Fifty-six layers of composite were determined to reinforce the complete defected area. Working at 19-meters depth is a shallow water job. At this depth, divers can dive for about 70mn. Divers are equipped with umbilical sets allowing them to breathe and communicate with the control room. These divers are previously trained by 3X supervisor to complete all the steps of the repair.

Surface preparation was completed using gritblasting to get an optimal surface roughness and ensure a good bonding between the pipe and the composite repair. To blast the full area to be repaired, it took 4 dives. The composite repair was then completed following 5 main stages, as below:

1/ Marking and measurement of the defects + P3X30 primer application on the defects to ensure a good bonding with composite plates.

2/ Composite plates covered with high-performance subsea F3XSB filler were positioned centrally on the defected locations and fasten with ratchet belts until the filler was cured (3 hours).

3/ Another layer of P3X30 primer was applied on the whole surface before composite wrapping.

4/ Composite wrapping was completed using Kevlar® tape impregnated with R3X65S resin. The tape impregnation was quickly performed using BOBIPREG device inside the container before immersion device. The subsea wrapping was performed by 2 divers to control the wrapping quality. It was necessary to apply 56 layers of composite material ==> total of 52 Kevlar® tapes installed in less than 20 hours for a total repair length of 2500mm.

5/ Protective cover against rocks and serial number plate were installed on the composite wrapping to finalize and validate the repair.

Results

Samples of resin were taken during each tape impregnation for quality control. Hardness measurements were performed 3 days after job completion and concluded the success of this subsea repair.

Composite wrapping in progress

Repair overview with rock protection and ID plate