Summary
Objective
Assess currently available composite repair systems for steel pipes and their applicability and limitations in various repair scenarios. Use this assessment as a basis for developing methods to expand the applicability of composite repair systems for more demanding scenarios.
Introduction
Pipe repair currently available are used increase the hoop stress resistance of pipes that have that have suffered a thinning of the wall due to external corrosion. These repair systems can be applied while the pipe is in service (flowing) in service. Typical applications are for pipelines or flowlines risers that are rigidly attached to the legs of fixed platforms, as shown below.
Application is currently limited to situations where there is no leakage, at elevations above the splash zone, in areas where little bending is expected, and below the deck away from process equipment.
These repair systems will be reviewed to provide guidance regarding the applications to various repair situations, and to if such repair techniques can be improved or extended (e.g. different fiber wrap geometries to provide bending resistance, different fiber/epoxy systems to reduce concerns of the performance of the composite patch near the splash zone.
Benefits to MMS & Industry
The assessment of currently available composite repair systems will provide MMS guidance regarding the expected effectiveness and safety of such repair systems. The development of concepts to extend and/or improve these repair methods would allow more cost effective pipe repair options
Deployment of Results
The assessment of existing repair methods and practices would be documented in a report to the MMS, and that report could serve as a basis for MMS guidelines on the applicability of various repair scenarios. Concepts to extend and/or improve these repair methods would be documented and presented to the MMS and industry. The industry would be responsible for the final development and testing of any concepts to extend and/or improve composite repair techniques.
Project Plan
Scope and Plan:
Task1 – Gather information on the current state-of -the-art of composite repair systems and practices from the literature and discussions with contractors.
Task 2 – Define anticipate loads (e.g. wave, thermal) on the risers, and determine the stresses that a repaired riser would have to be able to safely withstand.
Task 3 – Document the range of and limitations on the applicability of existing repair systems, and prepare interim report for MMS.
Task 4 – Identify opportunities and concepts to improve or extend these systems to more demanding repair situations, and complete analytical design studies to develop improved wrap and/or materials (fibers, epoxies) for composite repairs.
Task 5 – Demonstrate the effectiveness of the concept(s) to improve/extend composite pipe repairs through limited small scale testing.
Task 6 – Prepare Final Report documenting project findings and results.
Related Publications
Assessing the Use of Composite Materials in Repairing and Reinforcing Offshore Riser Pipes, OTRC presentation by Chris Alexander – Stress Engineering Services Inc at the Regional Operations Technology Assessment Committee (ROTAC) Meeting of Minerals Management Service – Pacific OCS Region, September 19, 2006.
