PSI - Issue 47

ScienceDirect Structural Integrity Procedia 00 (2022) 000 – 000 Structural Integrity Procedia 00 (2022) 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 47 (2023) 417–425

27th International Conference on Fracture and Structural Integrity (IGF27) Interaction of Two Growing Corrosion Pits on the Surface of a Spherical Pressure Vessel L.A. Almazova a , O.S. Sedova a , S.A. Kabritz a * a Saint Petersburg State University, St.Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia 27th International Conference on Fracture and Structural Integrity (IGF27) Interaction of Two Growing Corrosion Pits on the Surface of a Spherical Pressure Vessel L.A. Almazova a , O.S. Sedova a , S.A. Kabritz a * a Saint Petersburg State University, St.Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg, 199034 Russia

Abstract Abstract

© 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 IGF27 chairpersons In the paper, two growing corrosion pits on the surface of a spherical pressure vessel are considered. The rate of their growth is supposed to be linearly dependent on the maximum principal stress at their bottom. The effect of different geometrical parameters, including distance between the defects, on the maximum stresses and the pit growth rate is analysed. For the considered parameters, the growth rate of a certain pit is not significantly affected by the presence of the second pitting, even when the distance between them does not exceed their radii. The depth of the pits has hardly noticeable effect on the maximum stresses and the growth rate. A decrease in the radii of the vessel, its thickness being fixed, leads to a reduction in the maximum stresses at the bottom of the pits; the growth rate of the pits also slightly decreases with decreasing radii of the vessel. The distance between the pits affects the stress distribution around the pits: for relatively large distances, pits do not influence each other and the maximum stress is reached at the bottom of the pits, while as the distance decreases, the interaction between pits begins to appear and the maximum stresses are observed at the edge between the pits. © 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 IGF27 chairpersons Keywords: Pitting corrosion; Stainless steel; Surface defects; Finite element analysis; FEM; Spherical shell; Stress state; Pressure vessels In the paper, two growing corrosion pits on the surface of a spherical pressure vessel are considered. The rate of their growth is supposed to be linearly dependent on the maximum principal stress at their bottom. The effect of different geometrical parameters, including distance between the defects, on the maximum stresses and the pit growth rate is analysed. For the considered parameters, the growth rate of a certain pit is not significantly affected by the presence of the second pitting, even when the distance between them does not exceed their radii. The depth of the pits has hardly noticeable effect on the maximum stresses and the growth rate. A decrease in the radii of the vessel, its thickness being fixed, leads to a reduction in the maximum stresses at the bottom of the pits; the growth rate of the pits also slightly decreases with decreasing radii of the vessel. The distance between the pits affects the stress distribution around the pits: for relatively large distances, pits do not influence each other and the maximum stress is reached at the bottom of the pits, while as the distance decreases, the interaction between pits begins to appear and the maximum stresses are observed at the edge between the pits. © 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 IGF27 chairpersons Keywords: Pitting corrosion; Stainless steel; Surface defects; Finite element analysis; FEM; Spherical shell; Stress state; Pressure vessels

1. Introduction 1. Introduction

* Corresponding author. fax: +7-812-428-71-59. E-mail address: y.pronina@spbu.ru * Corresponding author. fax: +7-812-428-71-59. E-mail address: y.pronina@spbu.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 IGF27 chairpersons 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 IGF27 chairpersons

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 IGF27 chairpersons 10.1016/j.prostr.2023.07.083