R4D, Internal and external corrosion – Angola

Oil & Gas
DEFECT TYPE Internal and external corrosion
DETAILS PIPES DETAILS: 6" WAG line , Offshore topside, design pressure 347 bars, max operating temp. 38°C


The objective of the repair, carried out by 3X ENGINEERING (3X) and its local distributor 3A SERVICES was to reinforce a 6″ gas line suffering from internal and external corrosion. The defected area is located above the flange and the corrosion expanded circumferentially on approx. 1.8m. External corrosion is notified on 3 areas: on the straight line above the bend, on the bend and on the straight line between the bend and the flange. To restore pipe integrity and prevent further deterioration, it was decided to repair the defected areas using REINFORCEKiT® 4D, approved by ABS.


According to ASME PCC-2 standard and 3X calculations, it was decided to apply REINFORCEKiT® 4D using R3X70+ resin (specifically dedicated to internal and external corrosion at high temperature). 30 layers of composite were determined to reinforce the straight line above the bend, 36 layers for the bend and 48 layers for the straight line near the flange.

Surface preparation was completed with sandblasting and Bristle Blaster® machine to get a good surface roughness (superior to 60µm Rz) and ensure a good bonding between the steel pipe and the composite repair. Hygrometric conditions were checked and the surface was cleaned with acetone.

The composite wrapping repairs were then completed following below stages (application procedure is the same for the 3 areas to be reinforced).

1/ F3XS1 filler application on the defected areas (straight lines and bend) to reshape the pipe.

2/ One layer of R3X70+ resin application on the defected areas (same as above) to protect the prepared surfaces from corrosion.

3/ Composite wrapping was completed using Kevlar® tape impregnated with R3X70+ resin ==> 30 layers completed for a total repair length of 815mm for the straight line above the bend / 36 layers for a total repair length of 874mm for the bend / 48 layers for a total repair length of 703mm for the straight line near the flange.

4/ Finishing stage ==> last layer of R3X70+ resin applied all over the repair and id plate installed for traceability.


Hardness measurements were performed and concluded the good achievement of the repairs. The job was quite complicated because of several criteria : high temperature + gas line + pipe geometry but was completed successfully by 3X specialists using REINFORCEKiT® 4D product.
The design life for this composite reinforcement is 10 years ==> ABS APPROVED.

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