NRI Featured In World Pipeline – Composite Repair

Pipeline Composite Repair System As featured in the June issue of World Pipelines

Composite Repair: The Right Mix

Matt Green, NRI, USA, examines the importance of case specific engineering and design.

If there is one thing that can be said for composite repair systems, it is that they are one of the fas growing and most popular options for the repair of corroded pipelines. With their lightweight construction, high strengths and easy installation it is no wonder they are becoming a preferred option for repairing corrosion defects, dents and third party damage. Numerous ing programmers have been completed on a wide range of composite repair systems and varying component ingredients. As with most materials in any industry, each system and ingredient options have their merits as well as their downfalls. What is important is that the system under evaluation is fit for the intended usage. It is not simply a matter of this product can do this or that material is used for that. The beauty of a composite repair system is that each one can be designed for the application at hand.

So does that mean that any composite system can be used for any application? No, not necessarily. The ASME PCC-2 and ISO/TS 24817 documents clearly define the qualification ing and requirements for design of a composite repair based on the system properties and the pipe specifications and defect.  However. while a specific system may qualify, that does not always mean it is the best fit for the current, specific need.One example oF this is the fibre chosen to provide the structural properties of the repair system. A carbon fibre option may be chosen and represented in the repair system. and while this fibre is one of the strongest currently used in most commercial products to date, for many repair needs, it may be overkill and a glass fibre could perform more than sufficiently. This ís where the engineering behind the composite repair systems and design comes into play and working with a manufacturer that has ed and qualified numerous options can make all the difference in the world.

Custom design options

The idea of composite repair systems is definitely becoming more widely accepted in the oil and gas industry on a global scale. What makes them an attractive option for usage in the field for the repair of pipelines is not only the ease of the product and its application, but also that they can be designed on an as needed basis for each individual repair location need. This means that custom design options can be quickly created during inspections, direct assessments, or after inline inspections have been completed. The ability for a pipeline owner/operator to quickly design a repair option while an inspection is being completed is invaluable as the majority of cost involved with performing a pipeline repair is found in the cost of excavation and keeping the hole open. Many times there is no ability to wait for clamps to be manufactured, no allowance for welding a live line or the ability to get the necessary equipment onsite to perform any other repair option.

Remote Location Pipeline Repair
Figure 1. Remote locations sometimes dictate what can and cannot be used for pipe repair.

As numerous as the benefits are for composite repair systems for repairing pipeline, it is of crucial importance that the knowledge of the repair system, its properties, capabilities and limitation are fully understood. While untrained personnel can carry out many low pressure or low risk applications on small diameter piping, a truly engineered and designed repair system takes more than just a hands-on skill set. How can a pipeline owner/operator determine the best fit for their needs, or the best company to supply the composite repair system? While this seems like a simple question, it is far from a simple answer. The ASME and ISO documents previously mentioned provide guidelines as to how a composite repair system can be evaluated for qualification and ing requirements. However, it is still up to the owner/operator to fully evaluate each composite repair system as well as the manufacturer, including the engineering support staff dedicated to the system.

Pipe Repair Dig Location
Figure 2. Pipeline repair dig site location.

The manufacturer or supplier of the composite repair system must be able to provide full engineering and technical support on the repair system as well as full knowledge and understanding of the design of individual repairs. It is only when all aspects of the composite repair system are known and understood that a truly effective repair be created. Having the ability to choose from a variety of fibre options and architectures and resin matrices can be a valuable tool for the engineer designing the repair system. This has been the approach and goal of NRI for more than 10 years (ever since the first set of industry documents were bing created) and with more than five different composite repair systems fully qualified to the ASME and ISO documents. It is a great benefit when designing repair systems for pipelines.

There is a tendency to rely on older repair methods simply because there is a comfort level with what has “always worked” for repair needs. It is a growing opinion in the industry today that composite repair materials are just beginning to enter the time of “acceptance” since they have now been used in the field for almost 20 years for various repair needs. These successful field usages combined with a bevy of in depth ing programmes conducted by the Gas Technology Institute (GTI), Stress Engineering Services (SES) and Pipeline Research Council International (PRCI) have proven that composite repair materials can withstand harsh operating and environmental conditions. As more owner/operators utilize composite repair systems within their pipeline systems, there are more case histories for them, which continue to strengthen the case for this beneficial and cost-effective repair method.

Case Study: Northern Europe

Direct Assessment Inspection of Corroded Pipeline
Figure 3. Direct assessment inspections of the corroded pipe.

One such instance of a pipeline owner operator taking advantage of the benefits of composite repair materials was during a pipeline repair programme in northern Europe. After their inline inspection report was completed and reviewed, it was determined that more than 200 points required remediation as they were above the wall loss criteria for their systems. It then fell to the operator to determine the best course of action for the pipeline to meet the demands of regulation authorities while also meeting the demands of the owners to maintain operation of the pipeline to avoid loss of revenue. Various options were examined and it was decided that a composite repair system was the best method to balance the needs of all parties involved, get the pipeline repaired and maintain the profitability of the system overall. With the ability to maintain operations during repair, no requirements of additional heavy machinery or tooling, fast installations and cost savings associated, it was an easy choice for the pipeline.

Carbon Fibre Composite Repair System
Figure 4. Successfully repaired using the Viper-Skin™ carbon fibre composite repair system.

Each repair area was assessed based on the inspection report and a composite repair system was designed based on the parameters of the pipeline, operating the design conditions, and severity and type of the defects. Once complete, each repair was reviewed and during each repair location project, the specific defect was directly assessed for accuracy to the inspection report to confirm that the design of the composite repair maintained relevance for the repair. Any defect that was found to be outside of the calculated repair parameters was quickly re-assessed and additional layers could be applied as necessary. The flexibility of the repair system design and field personnel working in conjunction with the manufacturer’s engineering department insured that all repairs were fit for service even if they were not exactly as indicated on the inline inspection report.

Conclusion

The design and engineering of the composite repair systems are of critical importance to the success of the final, applied product. Manufacturing a great system does not automatically mean that the system will be successful. Material properties are easy to determine and installation can be a learned skill, but without the proper knowledge of composite materials and engineering to support the repairs being made, there can be no assurance that what was installed can do what is required. Working with the right professionals for composite repaire systems, as with any product in any industry, will make all the difference and can keep your pipeline running smoothly.