PSI - Issue 26

Available online at www.sciencedirect.com Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com ScienceDirect

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 26 (2020) 219–224

© 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of MedFract1 organizers Long-term operation of natural gas transit pipelines causes degradation of physical and mechanical properties of pipeline steels, which adversely affects their performance functions. These effects are generally not considered during their initial design. However, degradation degree of steel properties should be taking into account in evaluation of residual life-time of pipeline. Therefore, there is a need to evaluate the material degradation degree under operation. In-service degradation of mechanical and electrochemical properties of pipeline steels with different strength was analysed. Some peculiarities of evaluation of degradation degree of pipeline steels, using non-destructive methods, were distinguished. Instrumented indentation testing is reliable method for assessing the metal degradation degree at the stage of deformation aging. However, a usage of indentation method can be limited if degradation degree of a tested metal is high, when the second degradation stage associated with dissipated damaging is dominated. Electro chemical method enables quantitative evaluation of degradation degree of operated pipeline steels and prediction of brittle fracture resistance, namely impact toughness, at any stage of degradation, including the stage of dissipated damaging. © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of MedFract1 organizers Keywords: pipeline steel; degradation; hydrogen; operation; electrochemical analysis; indentation; brittle fracture resistance . T The 1 st Mediterranean Conference on Fracture and Structural Integrity, MedFract1 Non-destructive evaluation of operated pipeline steel state taking into account degradation stage Olha Zvirko*, Oleksandr Tsyrulnyk, Hryhoriy Nykyforchyn Karpenko Physico-Mechanical Institute of the National Academy of Sciences of Ukraine, 5, Naukova St. Lviv 79060, Ukraine Abstract

1. Introduction

Pipeline integrity is growing and challenging problem since age of pipelines transporting natural gas is increasing. Gas transit pipelines, due to their age, are subject to aging and degradation, which causes deterioration of pipeline steel

* Corresponding author. Tel.: +380-32-229-6294; fax: +380-32-264-9427. E-mail address: olha.zvirko@gmail.com

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of MedFract1 organizers

2452-3216 © 2020 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of MedFract1 organizers 10.1016/j.prostr.2020.06.025