Subsea Pipelines Repair
When they are located subsea, damaged pipelines are very challenging to repair. The extreme conditions, the risks related to pollution and the high daily rates of intervention vessels make the repair decision difficult.
Recently, composite repair solutions, originally developed for onshore use, where adapted for subsea application and tested, so as to get alternative solutions to apply when classical repair methods are not suitable or too costly.
Composite repair system for subsea use
Composite repair solutions for restoring the structural integrity of damaged pipeline have been available for some time. A modified version was specifically designed for subsea pipeline repair, using a dedicated resin applicable under water.
The repair system is designed to be installed by divers with a semi-automatic installation process: using pre-impregnated tape with a specific tool applying constant tension and winding path. This tool is now being adapted for ROV use, to allow performing deepwater repairs.
Results, Observations, and Conclusions
Several test campaigns, both in swimming pools and subsea were performed in Monaco, Abu Dhabi and in China for various oil operators, with a rigorous test protocol, supervised by a third party.
A finite element model of the composite repair allows calculating the number of layers, pattern and extent over the defect, in relation to the stress level in the pipe. This FE model was also validated through numerous burst tests, confirming the reliability of the calculations.
The subsequent pressure test results indicated that the pipeline integrity was fully restored for damages such as metal loss and through thickness defects.
A solution for restoring the structural integrity of a damaged pipeline
This composite repair system is designed to restore fully the structural integrity and pressure resistance of the pipeline for subsea application. It represents a cost efficient alternative to classical repair methods involving clamps, mechanical connectors or others.