This case study presents a technical assessment of the Glass Reinforced Plastic (GRP) piping system installation at a power plant, based on a visit conducted at its site. The evaluation focused on the material quality, engineering, and site installation activities for the project’s cooling water and firewater systems. Particular attention was given to the GRP piping, with a secondary overview of the High-Density Polyethylene (HDPE) firewater system.
Pipe Material Quality
This case study presents a technical assessment of the Glass Reinforced Plastic (GRP) piping system installation at the site, based on a site visit conducted in 2023. The evaluation focused on the material quality, engineering, and site installation activities for the project’s cooling water and firewater systems. Particular attention was given to the GRP piping, with a secondary overview of the High-Density Polyethylene (HDPE) firewater system.
Joint Fabrication and Quality Control
On-site observations of the joint fabrication process, involving grinding and laminating, indicated generally good workmanship. However, there is not much installation supervision to guarantee good quality components.
Field hydrotesting is deemed critical for validating joint and system integrity. The recommended procedure involves a performance test at 1.5 times the design pressure (9 bar) for two hours, followed by a leak tightness test at 1.1 times the design pressure (6.6 bar) for 24 hours. Detailed records of hydrotest packages, including test outcomes and retests, are required for quality assurance.
Storage Conditions and Material Handling
No guidelines were mentioned for the storage of resin and glass fibres. The storage conditions for resin were deemed to be acceptable. Glass fibres were stored at temperatures and humidity levels exceeding the manufacturer’s recommendations. Exposure to higher temperatures and humidity leads to deterioration, reducing its effectiveness as a reinforcement.
The absence of specific storage requirements in the vendor’s method statements was highlighted as a process shortcoming. It was recommended that resin containers be better insulated or shaded and that glass fibre materials be stored in air-conditioned spaces to maintain optimal conditions.
Installation and Burial Practices
Proper burying and backfilling of GRP pipes is important to prevent mechanical damage and ensure long-term performance. During the site visit it was observed that in some cases sand was used as backfill, whereas the design calls for crushed rock as the backfill material. Additionally, it was found that the backfill soil was not compacted and foreign objects, such as rock materials, were not removed from the trench.
Key Takeaways and Recommendations
Based on the site visit and assessment of the GRP piping installation, the following was concluded:
- Delamination in GRP pipes, likely linked to the fabrication method, poses a significant risk to system integrity and must be systematically identified and prevented.
- Proper storage of resins and glass fibers is essential to preserve material properties and ensure high-quality joints; method statements should explicitly define storage requirements.
- Comprehensive field hydrotesting of all piping sections is required for confirming system readiness and must be thoroughly documented.
- Installation practices, particularly those related to trench preparation, backfilling, and compaction, have a direct impact on the long-term performance of buried piping systems and require close supervision and adherence to best practices.