Going Beyond ASME B31.12: A Technical Feasibility Case Study for the Conversion of a 16” X 20 km Onshore Gas Pipeline to Hydrogen Storage

Abstract The conversion of existing assets to hydrogen needs to be managed with due diligence. Current industry codes such as ASME B31.12 have remained relatively immature in their approach to repurposing and do not yet reflect the rapidly evolving research developments in this areas, for example accounting for the presence of historic defects and damages. This paper proposes a method for pragmatic and safe pipeline repurposing that presents the project with an early screening of major barriers that may potentially compromise repurposing. In line with current industry knowledge, this approach includes the removal of conservatisms associated with some of the design equations given in existing codes i.e. ASME B31.12. The case study provided to illustrate this process is a 20 km 16″ pipeline proposed for conversion to hydrogen storage. The overall objective was to define a safe operating envelope within which the capacity of all segments of the vintage pipeline can be maximized. The input data, assumptions made where data was unavailable or incomplete, engineering critical assessment methods and defect compliance criteria, and results are provided. The operating envelope is tested against potential H2 operating cases, and a test and inspection plan proposed to confirm the assumptions made as future work. Conservative decisions in light of open industry gaps are highlighted where applicable. The study provides a clear, documented demonstration of feasibility for hydrogen storage within a specified operating envelope of restricted pressure and pressure cycling before further committing to subsequent repurposing strategy phases.