Plastic Pipes Conference Association # 2023 Lake Buena Vista
Carine Lacroix, Philippe Louvel, Danielle Mark, Dominique Gueugnaut
A test program was carried out on two Polyamide resins, Polyamide 11 (PA11) and Polyamide 12 (PA12), both certified for gas networks. Polyamide’s advantage lies in its implementation, similar to that of polyethylene, and its properties allowing it to operate at up to 18 bar for gas, all other conditions being equal. This material is therefore of strategic importance in the development of natural gas networks, and for new gases.
The aim of the study was to evaluate the robustness of Polyamide network installation, with a focus on installation and fusibility in normal and harsh operational conditions. Electrofusion, on tapping saddles, and Butt fusion of PA11 and PA12 were tested. With pipelines or fittings fused “as received” or voluntarily aged or saturated with water, quality of PA fusion was evaluated. Cross-fusion of PA11 and PA12 was also evaluated.
Results obtained from tear tests showed that there is an influence of water saturation of the pipeline on the quality of the fusion. PA 11 and PA12 also showed some differences in behavior, regarding both water saturation and fusion capability.
However, even if the harmful influence of prolonged exposure to humidity on fusibility has been widely demonstrated, it remains to be understood how representative the water saturation caused by immersion in baths at 80°C is, compared to real conditions. In operational conditions, in a 100% wet soil, at a temperature of about 15°C, the time required to saturate the surface of a buried PA pipe with water would be about 200 days.
The results from this study show that under operational conditions, extreme caution is necessary for fusion operations on polyamide networks buried in a wet environment, or incorrectly stored. An adaptation of the fusion protocols for these degraded cases should be considered. To establish these protocols, work with suppliers of materials and fittings is necessary
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