Phase 1 – Legacy Pipeline Material Data Survey and Assessment
Phase 1 will determine the range of materials used in legacy pipelines that are being considered for conversion to hydrogen service by the pipeline operators participating in the project. Once this range of materials of interest is established, the program will review previous and current research work and existing data sets to identify opportunities where there is both a comprehensive set of material test data for a pipeline system and available pipe specimens that can be used for small- and large-scale testing in hydrogen.
Phase 2 – Material Small-Scale Hydrogen Exposure Testing
Phase 2 will establish the impact of hydrogen exposure on pipeline material performance. An initial series of material property tests will be conducted in ambient conditions (in air) to establish the baseline for assessing the impact of hydrogen service on the material. The second series of small-scale tests will conduct a similar series of tests with continuous hydrogen exposure throughout the test. This will allow slow strain rate or cyclic load tests that are representative of the hydrogen environment in-service without concerns for hydrogen desorption during testing.
Phase 3 – Full-Scale Hydrogen Exposure Testing
Phase 3 will consist of tests of full-cross section line pipe specimens in hydrogen environments. These tests will be used to identify any differences in behaviour between small-scale and large-scale tests. The full-scale tests will consider specimens with features such as welds, wall loss or dents; depending on specimen availability. Tests could include monotonic or cyclic pressure tests with continuous exposure to the hydrogen environment.
Phase 4 – Material Classification and Performance Modelling
Phase 4 will bring together the information and test results from the program to classify materials considered in the program in terms of their susceptibility to hydrogen environments. The effects of hydrogen on material performance will be built into deterministic models to assess how future pipeline operating pressure profiles and pressure cycles in hydrogen service impact remaining pipe life. A probabilistic modelling approach will also be used to account for the many uncertainties in the model inputs to provide a reliability model for legacy pipelines in hydrogen service. The results of these analyses may also provide guidance for developing codes and standards for assessing the performance of other legacy pipeline materials that were not evaluated in this project.