Hydrogen conversion of existing pipelines: integrity solutions

Background: In the global transition to low-carbon energy, hydrogen is becoming an important energy carrier. Adapting existing pipelines for hydrogen transportation can reduce costs and accelerate the development of hydrogen infrastructure. However, the use of pipelines in a hydrogen environment is associated with risks such as hydrogen embrittlement and metal cracking. Kazakhstan still lacks practical experience in the operation of hydrogen pipelines, which makes the task of assessing the technical condition of existing pipelines and their adaptation for operation with hydrogen urgen. Aim: To conduct a comprehensive analysis of the integrity of the pipeline operated in an aggressive hydrogen sulfide environment and to assess the possibility of its repurposing for hydrogen transportation taking into account international standards and methods of strength calculation. Materials and methods: The data of in-line inspection (ILI) including ultrasonic testing of wall thickness were used in the work. API 579 standards were used for defects assessment. Calculations were performed using NIMA software, which allows analyzing data on laminations and cracks in metal. Results: The analysis identified six sections with laminations, of which five were found to be acceptable for service at the current operating pressure of 75 bar. One defect (#6) was classified as unacceptable, requiring either immediate repair or a reduction in operating pressure to 52 bar. Conclusion: The study confirmed that conversion of existing gas pipelines for hydrogen transportation is feasible provided thorough diagnostics and compliance with international standards for strength assessment. Implementation of regular pipeline condition monitoring and development of a phased repair strategy to improve infrastructure reliability in hydrogen environment is recommended.