Offshore CompoSol® Subsea
Equatorial Guinea Riser
A platform situated in the Gulf of Guinea had serious problems with the corrosion of a riser beneath the water-line. The pipeline had already been repaired with a competitor wrap repair system; however this repair had de-bonded from the substrate and was therefore no longer offering corrosion protection. IMG Composites were contacted and asked to provide a solution. With a CompoSol® Subsea repair solution the corrosion was arrested and the substrate was protected for a warranted service life of 20 years.
The riser had a relatively high operating temperature. Although the temperature was within the operating limits of a cured CompoSol® Subsea repair, it increased the likelihood of an improperly cured repair, and was also potentially harmful to the applicators. Consequently, the riser was shut down during application. However, there was little loss in production as flow was diverted through a separate pipeline for the duration of the application.
The application procedure required the riser to be sandblasted by divers to remove marine growth and surface corrosion so the surface of the substrate was prepared to SA2.5 standard. 400mm of the axial extent of the competitor repair was removed to assess the potential of adhesion of the repair to the substrate. Following surface preparation, reinforced epoxy paste was applied to form a smooth surface. Application of the CompoSol® Subsea laminate was performed by divers who wrapped the full circumference of the pipeline. It required a 50% overlap of the wrap to ensure adequate compression and that all excess air and water was expelled from the repair. The entire operation, from survey to cured repair, took ten days. After repair the pipeline was returned to service and the repair had a warranted service life of 20 years.