PSI - Issue 66

ScienceDirect Structural Integrity Procedia 00 (2025) 000–000 Structural Integrity Procedia 00 (2025) 000–000 Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Available online at www.sciencedirect.com ScienceDirect

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Procedia Structural Integrity 66 (2024) 525–534

8th International Conference on Crack Paths Nondestructive detection of internal pipe cracks in hydrogen-energy systems Yamato Abiru a , Hiroshi Nishiguchi a,* , Toshiya Itaya b Abstract In recent years, hydrogen energy has garnered significant interest for use as a clean, renewable energy source essential for achieving a carbon-neutral society. However, hydrogen ingress into metals may cause hydrogen embrittlement, reducing metal strength. Hydrogen-utilizing facilities typically use materials resistant to embrittlement, such as austenitic stainless steel SUS316L and aluminum alloy A6061-T6. Having said that, these materials are costlier than carbon steel, posing a barrier to widespread hydrogen energy adoption. Thus, several researchers are actively trying to replace these materials with more economical options, such as carbon and low-alloy steels. This paper aims to develop a nondestructive testing (NDT) technique to detect internal pipe cracks. We employed commonly used methods, specifically eddy current testing (ECT) and hammering tests (HT), to detect cracks in hydrogen-precharged and uncharged specimens. Experimental pipes, simulating those in hydrogen stations, were created with artificial cracks, and hydrogen-precharging was achieved by immersing specimens in a 20 mass% ammonium thiocyanate solution at 40°C for 72 h. The results indicated that crack growth and initiation rates were faster in hydrogen precharged specimens, reducing the cycle count required for cracks to reach the outer surface by approximately one tenth. The ECT effectively identified large cracks in hydrogen-precharged materials, although it struggled with smaller, internal cracks. Conversely, HT detected cracks at 0.78 mm in uncharged specimens and 2.04 mm in hydrogen-precharged specimens. Sensitivity was slightly lower for hydrogen-precharged specimens, as crack-specific peaks were absent below 1.93 mm, underscoring the need for tailored inspection methods in hydrogen-exposed materials . © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of CP 2024 Organizers Keywords: Hydrogen; Hydrogen embrittlement; Nondestructive testing; Eddy-current test; Hammering test; Crack propagation 8th International Conference on Crack Paths Nondestructive detection of internal pipe cracks in hydrogen-energy systems Yamato Abiru a , Hiroshi Nishiguchi a,* , Toshiya Itaya b a Sasebo National College of Technology, 1-1 Okishin-machi Sasebo City, Nagasaki 857-1193, Japan b Suzuka National College of Technology, 2191 Hirata-cho, Suzuka City, Mie 510-0294, Japan Abstract In recent years, hydrogen energy has garnered significant interest for use as a clean, renewable energy source essential for achieving a carbon-neutral society. However, hydrogen ingress into metals may cause hydrogen embrittlement, reducing metal strength. Hydrogen-utilizing facilities typically use materials resistant to embrittlement, such as austenitic stainless steel SUS316L and aluminum alloy A6061-T6. Having said that, these materials are costlier than carbon steel, posing a barrier to widespread hydrogen energy adoption. Thus, several researchers are actively trying to replace these materials with more economical options, such as carbon and low-alloy steels. This paper aims to develop a nondestructive testing (NDT) technique to detect internal pipe cracks. We employed commonly used methods, specifically eddy current testing (ECT) and hammering tests (HT), to detect cracks in hydrogen-precharged and uncharged specimens. Experimental pipes, simulating those in hydrogen stations, were created with artificial cracks, and hydrogen-precharging was achieved by immersing specimens in a 20 mass% ammonium thiocyanate solution at 40°C for 72 h. The results indicated that crack growth and initiation rates were faster in hydrogen precharged specimens, reducing the cycle count required for cracks to reach the outer surface by approximately one tenth. The ECT effectively identified large cracks in hydrogen-precharged materials, although it struggled with smaller, internal cracks. Conversely, HT detected cracks at 0.78 mm in uncharged specimens and 2.04 mm in hydrogen-precharged specimens. Sensitivity was slightly lower for hydrogen-precharged specimens, as crack-specific peaks were absent below 1.93 mm, underscoring the need for tailored inspection methods in hydrogen-exposed materials . © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of CP 2024 Organizers Keywords: Hydrogen; Hydrogen embrittlement; Nondestructive testing; Eddy-current test; Hammering test; Crack propagation © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of CP 2024 Organizers a Sasebo National College of Technology, 1-1 Okishin-machi Sasebo City, Nagasaki 857-1193, Japan b Suzuka National College of Technology, 2191 Hirata-cho, Suzuka City, Mie 510-0294, Japan

* Corresponding author. Tel.:+81-956-34-8451; fax: +81-956-34-8409. E-mail address: hiroshin@sasebo.ac.jp * Corresponding author. Tel.:+81-956-34-8451; fax: +81-956-34-8409. E-mail address: hiroshin@sasebo.ac.jp 2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. 2452-3216 © 2025 The Authors. Published by ELSEVIER B.V.

2452-3216 © 2025 The Authors. Published by ELSEVIER B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0) Peer-review under responsibility of CP 2024 Organizers 10.1016/j.prostr.2024.11.106 This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)Peer-review under responsibility of CP 2024 Organizers This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)Peer-review under responsibility of CP 2024 Organizers