Thermoplastic Composite Riser Guidance Note

摘要

A new class of flexible risers is being developed: bonded fiber reinforced thermoplastic risers. These risers have some characteristics which are similar to unbonded flexible risers and some similar to bonded composite risers, giving them very interesting overall properties. In order to apply this promising technology its functionality and safety should be ensured. For this reason a new guidance note is being developed in a joint industry project, describing design requirements, material characterization and test methods. The guidance note is performance based allowing a wide range of designs and optimization for the application. It addresses the design issues from the standards of related products, DNV-RP-F202 “Composite Risers” and API 17 J “Specification for Unbonded Flexible Pipe”. Since bonded thermoplastic fiber reinforced pipes are not directly covered in the existing riser standards, any aspects related to this class of material are developed new. An overview is given how the guidance note is organized and how the requirements are described. The guidance note addresses load cases and environments to consider. It lists the failure mechanisms that need to be controlled. It gives design criteria or test requirements for each failure mode to show that none of the critical failure mechanisms will happen during the design life. Full-scale test requirements are also addressed. Special emphasis is given to the end fittings. They will have to be qualified by a combination of analysis and testing. Since long-term performance is the most critical question for ensuring performance during the lifetime, cyclic fatigue and stress rupture (static fatigue) will have to be considered for all failure mechanisms and all environments. Long-term performance is characterized using the pyramid system. Basic properties are established on the material level based on many tests. Special conditions and component performance are tested on a few samples for comparison. Thermoplastic composite risers designed according to this guidance note should be fit for purpose during their design life.