PSI - Issue 48

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2023) 000 – 000

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ScienceDirect

Procedia Structural Integrity 48 (2023) 310–317

© 2023 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 the IRAS 2023 organizers Abstract Comprehensive inspections of several hydraulic units’ (HU) supporting structures at operating hydro power plants reveal main causes for crack formation in HU supporting structures after long-term operation. This also identifies characteristic areas most prone to crack formation. The inspection included the following: equipment operating mode analysis, previous tests analysis, non-destructive testing of the base metal as well as welded joint areas and fastening elements, while also structure strength and durability computational studies by methods of mathematical 3D-modeling. The main practical result is the conclusion that crack formation is inevitable in some welded areas of HU supporting structures even in case of meeting all operating conditions and with high quality of the repairs. This occurs mainly due to the high local stress concentration in the individual welds of the supporting structures under the influence of operational loads and the uneven distribution of stresses in identical structural elements. These factors were not taken into account in the design of HUs that have already been working for over 30 or 40 years. Over a long operating time, welds that bear the most load have accumulated damage, which is not detectable by traditional non-destructive testing methods. This accumulated damage reduces mechanical and fatigue characteristics of the material and leads to crack formation. As a result, there is an intense crack formation of the supporting structures in a number of units. It reduces the earlier modernization effectiveness and limits the HU lifetime overall by reducing inter-maintenance periods and increasing the amount of recovery repairs. The research results help to develop effective measures reducing the intensity of crack formation in HU supporting structures. These activities will be individual and highly dependent on the structure and operation modes of the equipment. © 2023 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) Second International Symposium on Risk Analysis and Safety of Complex Structures and Components (IRAS 2023) Crack Growth Causes in Supporting Structures of Hydraulic Units Evgeniia Georgievskaia a, * a Center of design and technological innovation LLC, 197022, Saint-Petersburg, Russia Abstract Comprehensive inspections of several hydraulic units’ (HU) supporting structures at operating hydro power plants reveal main causes for crack formation in HU supporting structures after long-term operation. This also identifies characteristic areas most prone to crack formation. The inspection included the following: equipment operating mode analysis, previous tests analysis, non-destructive testing of the base metal as well as welded joint areas and fastening elements, while also structure strength and durability computational studies by methods of mathematical 3D-modeling. The main practical result is the conclusion that crack formation is inevitable in some welded areas of HU supporting structures even in case of meeting all operating conditions and with high quality of the repairs. This occurs mainly due to the high local stress concentration in the individual welds of the supporting structures under the influence of operational loads and the uneven distribution of stresses in identical structural elements. These factors were not taken into account in the design of HUs that have already been working for over 30 or 40 years. Over a long operating time, welds that bear the most load have accumulated damage, which is not detectable by traditional non-destructive testing methods. This accumulated damage reduces mechanical and fatigue characteristics of the material and leads to crack formation. As a result, there is an intense crack formation of the supporting structures in a number of units. It reduces the earlier modernization effectiveness and limits the HU lifetime overall by reducing inter-maintenance periods and increasing the amount of recovery repairs. The research results help to develop effective measures reducing the intensity of crack formation in HU supporting structures. These activities will be individual and highly dependent on the structure and operation modes of the equipment. © 2023 The Authors. Published by ELSEVIER B.V. Second International Symposium on Risk Analysis and Safety of Complex Structures and Components (IRAS 2023) Crack Growth Causes in Supporting Structures of Hydraulic Units Evgeniia Georgievskaia a, * a Center of design and technological innovation LLC, 197022, Saint-Petersburg, Russia

Peer-review under responsibility of the IRAS 2023 organizers Keywords: crack ; hydraulic unit ; non-destructive testing ; residual life ; stresses Keywords: crack ; hydraulic unit ; non-destructive testing ; residual life ; stresses

* Corresponding author. Tel.: +7-921-971-64-43 E-mail address: sciencedir@cdti.ru * Corresponding author. Tel.: +7-921-971-64-43 E-mail address: sciencedir@cdti.ru

2452-3216 © 2023 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 the IRAS 2023 organizers 2452-3216 © 2023 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 the IRAS 2023 organizers

2452-3216 © 2023 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 the IRAS 2023 organizers 10.1016/j.prostr.2023.07.127