A unique high quality study to improve pipeline safety.

What is it about?

This study focuses on the safety and durability of pipelines used to transport hydrogen gas, which is important for reducing carbon emissions. Challenges include: - Hydrogen can weaken steel pipelines, especially in areas near welds, called heat-affected zones (HAZ). - These areas are more prone to cracking because of their hard and brittle microstructures. Researchers developed a method to mimic the microstructures found in these vulnerable weld regions by using heat treatments on steel samples. They tested three types of steel (older and modern) and four different microstructures, including the original base metal and three simulated HAZ microstructures. The tests were conducted in normal air and in high-pressure hydrogen gas to see how the steel behaves under these conditions. The results showed that hydrogen significantly reduces the strength and fracture resistance of the steel, especially in the hard and brittle microstructures. Older steel was found to be more vulnerable to cracking than modern steel due to its higher carbon content and impurities. The study highlights the importance of considering the specific microstructures in pipelines when assessing their safety for hydrogen transport.

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Why is it important?

The study highlights the critical importance of understanding the structural integrity of hydrogen transport pipelines, particularly in the heat-affected zones (HAZ) near welds, which are highly susceptible to hydrogen embrittlement. Tailored heat treatments were developed to replicate the microstructures in these vulnerable regions, enabling precise testing of their fracture resistance. The findings emphasize that hard and brittle microstructures, especially in older pipeline steels, are more prone to cracking in hydrogen environments. This research underscores the need for comprehensive assessments of pipeline materials and microstructures to ensure safe hydrogen transport, especially as existing natural gas pipelines are repurposed for hydrogen use.

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