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NDE & Inspection Techniques Applied to Composite Wrap Repairs
For the past several years, PRCI’s Design, Materials, and Construction (DMC) Technical Committee has been engaged in a number of studies on the performance of composite materials for pipeline repair and reinforcement. To complement this work, PRCI’s Operations & Integrity Technical Committee and ESR Technology recently completed a study and technical review on Non-Destructive Examination (NDE) & Inspection Techniques Applied to Composite Wrap Repairs. The project looked at the capabilities and limitations of a wide range of NDE technologies to monitor the condition of the feature beneath the composite wraps which prompted the repair and the condition of the composite material itself, i.e., delaminations, adherence to the pipe wall.
The report identifies the “Top Ten” NDE inspection technologies, with an individual ranking of each inspection technique. The ranking is dependent on the exact details of the repair that are of interest as different techniques will be expected to be suitable for the underlying substrate, the interface, and the composite wrap repair. The top ten techniques are based on the data gathered during the project and used in the gap analysis. Individual scores were ascribed in a spreadsheet to rate practicality, effectiveness, and other measures of each inspection method chosen for the overall repair and segmented into inspection of the substrate, the interface and the composite repair. PRCI members can download the report here.
An output of this report is a proposal for continued evaluation of NDE inspection techniques that are used for evaluation of composite wrap repairs through a Phase Two project with PRCI to evaluate the most promising inspection technologies for composite repairs identified. The proposed project builds on existing composite repair samples developed and tested as part of the separate studies being performed by PRCI under the DMC Technical Committee. The work would be coordinated with the contractors who are evaluating the integrity of composite repairs on behalf of PRCI, and will consist of an inspection campaign using the samples being prepared for that study using techniques which examine:
- Condition of steel pipe under the repair (using pulsed eddy current techniques and/or radiography, if suitable exposure bay is available).
- Condition of the interface (using laser shearography, microwave inspection and/or manual ultrasonics).
- Condition of composite repair (visual examination and/or AE during burst tests).
The proposed additional phase of work is included on the PRCI 2013 Research Program ballot and received substantial support and endorsement at the May 2012 Technical Committee meeting.