TESTING STANDARDS FOR COMPOSITE REPAIR SYSTEMS
It is common for industries to develop and implement testing standards. While their use by manufacturers of products in an industry is usually not mandatory unless required by regulatory bodies of the government, such standards provide many important benefits. These benefits include evaluating the suitability of new products, defining performance envelopes, comparing different products to determine which product to use, guiding research and development (R&D) activities towards the attainment of specific and well-quantified targets, and building credibility by demonstrating that a product will work as advertised.
This post summarizes the use of industry standards for composite repair systems. See the post titled COMPOSITE REPAIR SYSTEMS FOR FLUID SYSTEM COMPONENTS (created 11 November 2018) for background information on such systems.
American Society of Mechanical Engineers (ASME), Post-Construction Committee – 2 (PCC-2), Repair of Pressure Equipment and Piping, Article 4.1, “Non-Metallic Composite Repair Systems: High Risk Applications”, is an important industry standard for the qualification of composite repair systems for use in challenging applications involving the repair of fluid transport system components such as pipelines and pipework. It should be noted that European and other international standards, covering evaluations of aspects of composite repair systems similar to those covered by this ASME standard, are also available.
This comprehensive testing standard defines a repair system in terms of the combination of all of its elements, for which qualification testing has been completed:
- Substrate (repair surface), which may be either metallic or non-metallic.
- Surface preparation.
- Filler material for load transfer.
- Primer layer adhesive (only needed in some repair systems, to attach the composite laminate to the substrate).
- Composite material (repair laminate), which is required to incorporate continuous fiber reinforcement in a thermoset polymer matrix.
- Application method (including sealing, coating, etc., as needed).
- Curing protocol.
- Interlaminar adhesive (only needed for repair systems that utilize pre-cured plies).
The following types of defects can be repaired:
- External corrosion where structural integrity is compromised.
- External damage, such as dents, gouges, fretting or wear (at supports).
- Internal corrosion or erosion (leaking or non-leaking).
- Manufacturing or fabrication defects.
Many material and performance properties are measured as a part of the evaluation of a repair system according to this standard. One or more preferred ASTM and ISO standards are listed for each property that needs to be measured.
The following two images show data for Syntho Glass® XT, a composite repair system that was developed and tested rigorously according to this standard as well as other standards. Note that, in addition to ensuring that the product is of excellent quality, testing done according to the standard has also generated key performance data for the product as well as helping in the preparation of specific and detailed instructions regarding the best practices that field technicians should follow in installing systems.