R4D-S, External corrosion and leak in subsea environment – Middle East

Oil & Gas Subsea
DEFECT TYPE External corrosion and leak in subsea environment
DETAILS 48” oil line – max. op. temp. 25°C – calculated pressure 17.85 bars


The objective of the repair, performed by 3X ENGINEERING (3X) and its local distributor, was to reinforce a 48” subsea pipe damaged by external corrosion defect and leak at 5-meter depth.


According to ISO 24.817 and 3X repair calculations, 14 layers of R4D-S have been determined to reinforce the pipe section damaged by external corrosion and additional 46 layers of R4D-S to repair the leak.

Underwater, preliminary operations (pipeline excavation, defect localization etc …) were performed prior to surface preparation by grit blasting to get a good surface profile (superior to 60µm). Divers were trained prior to the installation to share all important information relative to 3X procedures.

The composite repair was performed following 2 stages of reinforcement:

1st STAGE 14 layers of R4D-S on approx. 27m to reinforce the section damaged by external corrosion.
1. P3X30 primer application on the whole surface to be repaired to ensure a good bonding of the composite system on the pipe.

2. Kevlar® tape impregnated with R3X1050S resin and wrapped around the pipe. The tape impregnation was performed using BOBiPREG® (3X specific machine allowing a quick and regular impregnation resin/fiber). Fourteen layers were necessary to repair the external corrosion defect (i.e. 7 passes of 50% overlap). Because of the important length of the repair and in order to achieve the expected performance according to 3X procedures, 27m could not be wrapped continuously. So, the 27m repair length was made in sections of 2m max. During this stage, 1.9m was free of composite centred on the leaking defect. This section was the last one to be wrapped (see below 2nd stage).

2nd STAGE Additional 46 layers on 1.2m to repair the leaking defect.
1. P3X30 primer application around the defect (the surface was freshly prepared using grit blasting before this targeted application).

2. F3XSS filler application to seal the leak. Filler was applied on a rigid composite plate, the plate was then given to the diver and positioned over the leak and fastened tightly with ratchet belts.

3. P3X30 primer application on the 1.9m section still to be reinforced.

4. Kevlar® tape impregnated with R3X1050S resin and wrapped around the pipe. This wrapping was done in 2 steps: 14 layers to reinforce the 1.9m free of composite + 32 layers on 1.2m length centered on the defect total of 46 layers.

Finalization and validation of the repair: reference plate positioning for traceability purpose + hardness measurements.


This project was the longer one performed by 3X in subsea environment and was successfully repaired using R4D-S despite the various complicated parameters: 48” large pipe diameter, leaking defect, 27-m length of repair requiring a composite wrapping in many sections.