New Polyamide With Improved Hydrolysis Resistance

Polyamide, particularly PA11, has been used in flexible pipes for number of years, and has demonstrated an excellent behavior for containment layer application because of its good mechanical properties. However, Polyamides are subjected to hydrolysis, a phenomenon accelerated by elevated temperatures and the acidity of the fluid. Polyamides can thus be used in a temperature domain which must be consistent with the level of ageing acceptable for flexible pipe applications (static or dynamic). The methodology to calculate PA11 life time is dependent on the temperature, acidity and the application detailed in API 17TR2. For several years, Technip has been working on the development and the qualification of a new polyamide with enhanced hydrolysis resistance. Therefore, a full qualification program including tests recommended by API 17 J, extrusion process validation and full-scale dynamic tests, has been performed. Moreover, in line with API 17 TR2, hydrolysis curves have been designed from a full set of ageing test results. These curves show that this new PA can be used at higher temperatures than those presented in the API. Technip has now completed qualification of this new High Performance Polyamide (HPPA) for the inner sealing layer in applications where the conveyed fluid is hot (up to 90°C) and contains a significant water cut during the whole life of the flexible pipe.