Long-term performance of a polymer composite repair system for gas pipelines

Although composite materials are used to repair and reinforce a variety of anomalies in high pressure transmission gas and liquid pipelines, there continues to be widespread debate regarding what constitutes a long-term composite repair. The United States regulations require that composite repairs must be able to permanently restore the serviceability of the repaired pipeline, while in contrast the Canadian regulations take a more prescriptive approach by integrating the ASME PCC-2 and ISO 24817 composite repair standards along with a requirement for establishing a 50-year design life. In this paper the author provides a framework for what should be considered in qualifying a composite repair system for long-term performance by focusing on the critical technical aspects associated with a sound composite repair. The presentation includes a discussion on establishing an appropriate composite design stress using the existing standards, using full-scale testing to ensure that stresses in the repair do not exceed the designated composite design stresses, and guidance for operators in how to properly integrate their pipeline operating conditions to establish a design life. By implementing the recommendations presented in this paper, operators will be equipped with a resource for objectively evaluating the composite repair systems used to repair their pipeline systems.

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Advanced Insights on Composite Repairs

Volume 2: Pipeline Integrity Management ◽

10.1115/ipc2012-90574 ◽

2012 ◽

Author(s):

Chris Alexander ◽

Jim Souza

Keyword(s):

Composite Materials ◽

Test Sample ◽

Repair System ◽

Strain Gages ◽

Composite Repair ◽

Pressure Cycling ◽

Repair Systems ◽

Long Term Performance ◽

Term Performance

In response to inquiries from pipeline operators regarding the long-term performance of composite materials, manufacturers have performed additional tests to evaluate the performance of their composite repair systems. Insights were gained through these additional tests that demonstrated the long-term worthiness of the composite system. Of particular importance were two types of tests. The first involved the application of strain gages between layers of the composite repair system that was used to reinforce a corroded pipe test sample. As the sample was pressurized the strain gages permitted a comparison between the measured values and design stresses per the ASME PCC-2 design code. The second series of tests involved pressure cycling a 75% corroded sample to failure. In addition to the inter-layer strain measurements, the pressure cycling provides an important insight regarding the long-term performance of the composite repair. This paper addresses how the ASME PCC-2 Code, along with additional well-designed tests, can be used to design a composite repair system to ensure that it adequately reinforces a given defect. As composite materials are being used to repair pipeline anomalies beyond the corrosion-only defects, it is essential that pipeline operators utilize a systematic approach for ensuring the long-term performance of composite repair systems.

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Long-term performance studies in a photorefractive polymer composite

10.1117/12.363890 ◽

1999 ◽

Author(s):

Erwin Mecher ◽

Francisco Gallego-Gomez ◽

Klaus Meerholz

Keyword(s):

Polymer Composite ◽

Performance Studies ◽

Photorefractive Polymer ◽

Long Term Performance ◽

Term Performance

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Strain-Based Design Methods for Composite Repair Systems

2008 7th International Pipeline Conference, Volume 2 ◽

10.1115/ipc2008-64076 ◽

2008 ◽

Cited By ~ 3

Author(s):

Chris Alexander

Keyword(s):

Finite Element ◽

Composite Materials ◽

Design Method ◽

Design Methods ◽

Strain Gages ◽

Composite Repair ◽

Reinforced Steel ◽

Long Term Performance ◽

Term Performance

Composite materials are commonly used to repair corroded and mechanically-damaged pipelines. Most of these repairs are made on straight sections of pipe. However, from time to time repairs on complex geometries such as elbows, tees, and field bends are required. Conventional design methods for determining the amount of required composite materials are not conducive for these types of repairs. Over the past several years, the author has developed a methodology for assessing the level of reinforcement provided by composite materials to damaged pipelines using finite element methods. Instead of stress as the design basis metric, the method employs a strain-based design criteria that is ideally-suited for evaluating the level of reinforcement provided to non-standard pipe geometries. The finite element work has been validated using experimental methods that employed strain gages placed beneath the composite repair to quantify the level of reinforcement provided by the repair. This paper provides a detailed description of the strain-based design method along with appropriate design margins for both the reinforced steel and long-term performance of the composite materials.

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State of the Art Assessment of Composite Systems Used to Repair Transmission Pipelines

Volume 1: Project Management; Design and Construction; Environmental Issues; GIS/Database Development; Innovative Projects and Emerging Issues; Operations and Maintenance; Pipelining in Northern Environments; Standards and Regulations ◽

10.1115/ipc2006-10484 ◽

2006 ◽

Cited By ~ 15

Author(s):

Chris Alexander ◽

Bob Francini

Keyword(s):

Composite Materials ◽

Third Party ◽

Composite Repair ◽

Critical Elements ◽

Research Organizations ◽

Repair Systems ◽

Long Term Performance ◽

Term Performance ◽

Transmission Pipelines

For the past decade there has been relatively wide acceptance in using composite materials to repair damaged gas and liquid transmission pipelines. There have been numerous independent research programs performed by pipeline companies, research organizations, and manufacturers that have contributed to the acceptance of composites as a legitimate repair material. Additionally, insights have been gained by both pipeline operators and composite repair manufacturers during field installations. ASME has also responded by adding sections to both the ASME B31.4 and B31.8 pipeline codes, as well as currently developing a repair standard for non-metallic composite repair systems by the Post Construction Committee. Stress Engineering Services, Inc. and Kiefner & Associates, Inc. have been integrally involved in assessing the repair of pipeline systems, with the former having been involved in performing full-scale testing and analysis on most of the major U.S.-based composite repair systems. The purpose of this paper is to provide for the pipeline industry a third-party evaluation of composite repair systems and information that is needed to properly evaluate how composite materials should be used to repair high pressure pipelines. The contents of the paper will include discussions on what critical elements should be evaluated for each composite system, items of caution and concern, and the importance of evaluation to ensure safe long-term performance.

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