Development of a Carbon-Fiber Composite Repair System for Offshore Risers

Abstract

Composite systems are a generally-accepted method for repairing corroded and mechanically-damaged onshore pipelines. The pipeline industry has arrived at this point after more than 15 years of research and investigation. Because the primary method of loading for onshore pipelines is in the circumferential direction due to internal pressure, most composite systems have been designed and developed to provide hoop strength reinforcement. On the other hand, offshore pipes (especially risers), unlike onshore pipelines, can experience significant tension and bending loads. As a result, there is a need to evaluate the current state of the art in terms of assessing the use of composite materials in repairing offshore pipelines and risers. The significance of the body of work presented herein is that this study is the first comprehensive evaluation of a composite repair system designed for the repair of offshore risers using a strain-based design method coupled with full-scale prototype testing. This paper presents findings conducted as part of a joint industry effort involving the Minerals Management Service, the Offshore Technology Research Center at Texas A&M University, Stress Engineering Services, Inc., and several composite repair manufacturers to assess the state of the art using finite element methods and full-scale testing methods. Representative loads for offshore risers were used in the test program that integrated internal pressure, tension, and bending loads. This program is the first of its kind and likely to contribute significantly to the future of offshore riser repairs. The end result of this study was the development of a carbon-fiber repair system that can be easily deployed to provide significant reinforcement for repairing risers. It is anticipated that the findings of this program will foster future investigations involving operators by integrating their insights regarding the need for composite repair based on emerging technology.

Design of fibre-reinforced polymer overwraps for pipe pressure

“…They concluded that the use of composite overwrap could restore the bursting pressure resistance of both types of repaired pipes to the level of undamaged pipes. Alexander (2007) and Alexander and Ochoa (2010) performed experiments in conjunction with FEA and based on the obtained results presented an innovative design to extend the existing composite repair techniques to offshore pipes. Their research led to an easily deployable CFRP repair system based on the limit analysis method and strain-based design techniques.…”

“…A proper repair method should not only reinstate the original pressure capacity but also meet general criteria, such as ease of installation and economic viability, in addition to addressing technical criteria such as being impact resistance and nongalvanic (Alexander et al, 2008).…”

The flexural properties of composite repaired pipeline: Numerical simulation and experimental validation

“…The technique used here, known as the double-elastic slope method was developed by Alexander [16] based on several industrial design codes and standards similar to Section 6-153 of ASME Boiler and Pressure Vessel Code, Section VIII, Division 2 [17]. The method required the load vs. strain response of uncorroded pipe to be simulated within an FE analysis and its gradient determined, i.e.…”

Study on Patch Bonding for Recovery of Damaged Carbon Fiber Reinforced Thermoplastics Subjected to Four-Point Bending Load

“…It is expected that CFRTP will be applied not only to racing cars but also to commercial vehicles (Goto et al, 2011). When considering commercial applications, CFRTP may require more demands for repair during the product's life time (Alexander et al, 2008;Liu et al, 2012). However, there are only a few studies that focus on the repair properties of CFRTP under the actual damage such as bending damage.…”