Composite repairs are a proven solution for addressing a wide range of pipe defects and are increasingly accepted across critical industries due to the many advantages they provide.
Key advantages include:
rapid installation
the ability to be applied while assets remain in service,
impressive strength-to-weight ratio,
does not corrode like metallic repairs,
no hot work required unlike welded repairs or traditional steel sleeves,
installs and cures at ambient temperature, without the need for added heat, and
prevents external corrosion from occurring in the repair area.
Over the past three decades, composite repairs have grown more common. Their applicability for numerous repair scenarios has motivated operators, manufacturers, and contractors to further test and validate systems for permanent repair solutions. These efforts have been reinforced through collaborative research projects across industries. In this article, we will review the history of validation and repair, including testing programs conducted by Advanced FRP Systems.
Carbon fiber composites have become more common for pipeline repairs.
Use of Composites for Pipeline Defect Repairs
Composites are widely used across industries for high-pressure and process piping for external and internal corrosion. Substantial testing and successful use cases demonstrate composites’ long-term performance as a repair.
Aside from corrosion features, other pipeline defects often require a case-by-case consideration of the defect’s particular characteristics(sizing, growth rate, location, context and history, environment, etc.). These defects include crack-like features, stress corrosion cracking (SCC), dents, and gouges. For geohazards, multiple threats may exist simultaneously, such as within a girth weld area. In all of the above situations, repair decisions must be made after considering all influencing factors.
History of Validation Programs Across the Pipeline Industry
Composite repairs have been evaluated for pipelines since the 1990s. Some of this research was conducted through the Pipeline Research Council International (PRCI), which brings together the world’s largest pipeline operators to collaboratively conduct research and testing to solve industry challenges. According to PRCI reports, over 35 different composite repair systems have been tested and evaluated for use in transmission and process piping applications.
At the time that composite repairs were being evaluated as a potential pipeline repair solution, PRCI facilitated several research projects related to composites. The timeline below provides insight into the breadth and depth to which composites have been assessed since 2010* with PRCI.
2010: State-of-the-Art Assessment of Composite Repair Systems
2012: Composite Repair of Mechanically Damaged Pipes
2012: NDE and Inspection Techniques Applied to Composite Wrap Repairs
2016: Guidelines for Using Composite Systems to Repair High Pressure Pipelines
2018: Composite Repair Load Transfer Study
2018: Study to Evaluate Delamination and Disbonding of Composite Repairs
2020: Inspection of Composite Repairs for Pipelines and Piping – Phase 3 NDE Trials
2020: Evaluating Composites in Reinforcing Mechanically Damaged Pipelines with Dent and Gouge
2020: Long-Term Composite Repair Study – Burst Test
2021: Evaluating Installation Techniques for Pipeline Repair Methods
*List is a representative sample, not a complete history
In addition to the projects facilitated by PRCI, there have also been several Joint Industry Programs (JIPs) among operators, composite manufacturers, contractors, and other stakeholders over the past 30 years. These JIPs may have covered gaps in knowledge from the collaborative PRCI projects or answered a specific question about a particular composite system.
History of Testing and Validation Programs Conducted by Advanced FRP Systems
View of computer monitor during a burst test for Advanced FRP’s composite repair system.
Advanced FRP has funded several testing programs for its own composite systems. See below for a review of a selection of testing done recently for Advanced FRP Systems’ composites.
Crack Testing
Advanced FRP’s full-scale crack testing program included both pressure cycling and burst testing of eight samples. Each sample was outfitted with EDM-machined notches to create 3-inch-long cracks approximately 50% deep. The goal was to demonstrate the ability of the installed composite material to restore the integrity of cracks in the LF-ERW (Low Frequency, Electric Resistance Weld) pipe samples.
The composite system successfully reinforced planar and crack-like defects, improving both burst capacity and overall fatigue performance. Several considerations must be observed to ensure successful composite reinforcement of crack defects:
It is critical to know both the crack length and its depth to design a high-performing repair.
The service environment of the pipeline must be considered for composite reinforcement of crack defects. While natural gas lines experience less aggressive pressure cycling, liquid lines experience higher pressure cycling, which may call for more conservative design factors.
Material manufacturing history of the pipe itself, such as the LF-ERW seam quality, heavily influences performance and must be considered when designing a solution.
Girth Weld Testing
The rise in girth weld failures in pipelines, particularly due to geohazard loading, has underscored the critical need for effective weld reinforcement solutions to ensure pipeline integrity. Girth welds, being the structurally weakest parts of a pipeline, are susceptible to failure from third-party damage, corrosion, weld defects, and geohazard-induced stress.
This testing program included subjecting girth weld samples to three extreme loading situations: 1) Bending and internal pressure, 2) Axial tension and internal pressure, and 3) Burst tests to the point of failure. The testing programs showed that composite reinforcement is well suited to support girth welds, so long as design inputs accurately reflect real geohazard loading and operational loading conditions.
Air Pocket Analysis
A separate testing program explored the impact of air bubbles within composite reinforcement systems.Using full-scale testing and Finite Element Analysis, it showed that while small air pockets are generally harmless, larger ones can weaken pressure capacity and compromise repair integrity.
Since composite wraps are often applied in the field, this research offers valuable insights into how to manage air pockets and whether they pose a risk to the long-term performance of the repair. It emphasizes the need for proper installation and quality control to ensure safe, long-lasting pipe repairs.
An elevated temperature testing program used coupons to demonstrate that carbon fiber composites behaved differently at different cure temperatures.
Elevated Temperature Testing
Another testing protocolusing coupons demonstrated that carbon fiber-reinforced composites perform differently at different cure temperatures, especially for those operating in elevated-temperature environments.
The findings of this testing program demonstrate that:
Carbon fiber-reinforced composites have different properties with different cure temperatures, especially for elevated-temperature service
Tensile modulus should sharply decrease when the temperature exceeds the glass transition temperature of the composite
Tensile modulus and strength inputs for design calculations should use elevated temperature properties of the composite
Testing protocols should be in place to understand the critical relationship between cure temperature and its impact on the composite system.
The Advanced FRP composite repair system has been involved with several different testing programs to validate its use for pipeline repairs.
History Of Testing & Validation For Composite Repairs for Pipelines
Composite repairs are a proven solution for addressing a wide range of pipe defects and are increasingly accepted across critical industries due to the many advantages they provide.
Key advantages include:
Over the past three decades, composite repairs have grown more common. Their applicability for numerous repair scenarios has motivated operators, manufacturers, and contractors to further test and validate systems for permanent repair solutions. These efforts have been reinforced through collaborative research projects across industries. In this article, we will review the history of validation and repair, including testing programs conducted by Advanced FRP Systems.
Use of Composites for Pipeline Defect Repairs
Composites are widely used across industries for high-pressure and process piping for external and internal corrosion. Substantial testing and successful use cases demonstrate composites’ long-term performance as a repair.
Aside from corrosion features, other pipeline defects often require a case-by-case consideration of the defect’s particular characteristics(sizing, growth rate, location, context and history, environment, etc.). These defects include crack-like features, stress corrosion cracking (SCC), dents, and gouges. For geohazards, multiple threats may exist simultaneously, such as within a girth weld area. In all of the above situations, repair decisions must be made after considering all influencing factors.
History of Validation Programs Across the Pipeline Industry
Composite repairs have been evaluated for pipelines since the 1990s. Some of this research was conducted through the Pipeline Research Council International (PRCI), which brings together the world’s largest pipeline operators to collaboratively conduct research and testing to solve industry challenges. According to PRCI reports, over 35 different composite repair systems have been tested and evaluated for use in transmission and process piping applications.
At the time that composite repairs were being evaluated as a potential pipeline repair solution, PRCI facilitated several research projects related to composites. The timeline below provides insight into the breadth and depth to which composites have been assessed since 2010* with PRCI.
2010: State-of-the-Art Assessment of Composite Repair Systems
2012: Composite Repair of Mechanically Damaged Pipes
2012: NDE and Inspection Techniques Applied to Composite Wrap Repairs
2016: Guidelines for Using Composite Systems to Repair High Pressure Pipelines
2018: Composite Repair Load Transfer Study
2018: Study to Evaluate Delamination and Disbonding of Composite Repairs
2020: Inspection of Composite Repairs for Pipelines and Piping – Phase 3 NDE Trials
2020: Evaluating Composites in Reinforcing Mechanically Damaged Pipelines with Dent and Gouge
2020: Long-Term Composite Repair Study – Burst Test
2021: Evaluating Installation Techniques for Pipeline Repair Methods
*List is a representative sample, not a complete history
In addition to the projects facilitated by PRCI, there have also been several Joint Industry Programs (JIPs) among operators, composite manufacturers, contractors, and other stakeholders over the past 30 years. These JIPs may have covered gaps in knowledge from the collaborative PRCI projects or answered a specific question about a particular composite system.
History of Testing and Validation Programs Conducted by Advanced FRP Systems
Advanced FRP has funded several testing programs for its own composite systems. See below for a review of a selection of testing done recently for Advanced FRP Systems’ composites.
Crack Testing
Advanced FRP’s full-scale crack testing program included both pressure cycling and burst testing of eight samples. Each sample was outfitted with EDM-machined notches to create 3-inch-long cracks approximately 50% deep. The goal was to demonstrate the ability of the installed composite material to restore the integrity of cracks in the LF-ERW (Low Frequency, Electric Resistance Weld) pipe samples.
The composite system successfully reinforced planar and crack-like defects, improving both burst capacity and overall fatigue performance. Several considerations must be observed to ensure successful composite reinforcement of crack defects:
Girth Weld Testing
The rise in girth weld failures in pipelines, particularly due to geohazard loading, has underscored the critical need for effective weld reinforcement solutions to ensure pipeline integrity. Girth welds, being the structurally weakest parts of a pipeline, are susceptible to failure from third-party damage, corrosion, weld defects, and geohazard-induced stress.
This testing program included subjecting girth weld samples to three extreme loading situations: 1) Bending and internal pressure, 2) Axial tension and internal pressure, and 3) Burst tests to the point of failure. The testing programs showed that composite reinforcement is well suited to support girth welds, so long as design inputs accurately reflect real geohazard loading and operational loading conditions.
Air Pocket Analysis
A separate testing program explored the impact of air bubbles within composite reinforcement systems.Using full-scale testing and Finite Element Analysis, it showed that while small air pockets are generally harmless, larger ones can weaken pressure capacity and compromise repair integrity.
Since composite wraps are often applied in the field, this research offers valuable insights into how to manage air pockets and whether they pose a risk to the long-term performance of the repair. It emphasizes the need for proper installation and quality control to ensure safe, long-lasting pipe repairs.
Elevated Temperature Testing
Another testing protocolusing coupons demonstrated that carbon fiber-reinforced composites perform differently at different cure temperatures, especially for those operating in elevated-temperature environments.
The findings of this testing program demonstrate that:
Testing protocols should be in place to understand the critical relationship between cure temperature and its impact on the composite system.
The Advanced FRP composite repair system has been involved with several different testing programs to validate its use for pipeline repairs.
To learn more about available composite repair systems and our validation programs, visit our Resource Library on our website, or check out our selection of whitepapers.