Session: 09-04-01 fracture and toughness for H2 pipelines

Paper Number: 133278

133278 - Comparative Fracture and Fatigue Testing of Selected Pipeline Microstructures in Gaseous Hydrogen Environment 

Abstract: 

An ongoing study is assessing the suitability of a variety of line pipe materials for use in gaseous hydrogen transmission pipelines. The study involves comparative fracture toughness and fatigue testing in gaseous hydrogen and in wet sour environments. Initial testing already published focused on the parent and seam weld centre line microstructures of an offshore 1970’s API 5L X60 grade material from a 36” diameter pipe joint.

This paper presents the results from a significant expansion of the study, to include a variety of other materials commonly present in Shell pipelines that are anticipated to be repurposed for use in hydrogen service. This includes the heat affected zone of the above vintage X60 material, a 2010’s era sour rated seamless X65 (SMLS, 10” OD) material that has been strained and aged, with tests carried out on both the parent pipe and girth weld center line, and finally the parent pipe microstructure of a late 1960’s X60 high frequency electric resistance welded pipe sample (HF-ERW, 12” OD).

This paper presents the fatigue and threshold fracture toughness performance up to 172 bar H2 (2500 psi) and compares the results to existing literature data. The fracture performance varied widely between microstructures, with better performance for the modern SMLS material microstructures compared to the parent microstructure of the vintage materials. The fracture performance of the vintage HF-ERW X60 in particular was lower than the 55MPa√m expected from literature. These differences are analysed and discussed in more detail in this paper.

This paper also presents the results from comparative tests carried out in low partial pressures of H2S, in an attempt to better narrow down the equivalence point between hydrogen gas and wet H2S service. As anticipated, the less aggressive sour service environment (NACE Region 1) is more comparable to gaseous hydrogen performance than the more severe NACE Region 3 previously used in earlier publications. Further investigations into the time dependent cracking phenomenon beyond that already reported for the X60 material are covered elsewhere.

The wider impact of these results on hydrogen pipeline design, pipeline repurposing, and integrity management are also discussed in this paper.

Presenting Author: Sarah Hopkin Shell Global Solutions International B.V.

Presenting Author Biography: Sarah Hopkin is a materials engineer in the hydrogen research department of Shell’s Projects & Technology research organisation. She focuses on understanding the technical challenges related to transporting hydrogen through pipelines and other transport and storage technologies for the hydrogen supply chain. Sarah previously managed the corrosion and asset integrity of Shell’s UK registered gas platforms in the southern north sea. She has a master’s degree in materials science from the University of Oxford, and is a Chartered Engineer with the Institute of Materials, Minerals & Mining. She has published several papers related to hydrogen embrittlement of steels.

Authors:

Sarah Hopkin Shell Global Solutions International B.V.
Bostjan Bezensek Shell Global Solutions UK
Tom Martin Shell Global Solutions International B.V.
Wim Guijt Shell Global Solutions International B.V.