PSI - Issue 16

Available online at www.sciencedirect.com ScienceDirect StructuralIntegrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com Scienc Direct StructuralIntegrity Procedia 00 (2019) 000 – 000

www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

ScienceDirect

Procedia Structural Integrity 16 (2019) 141–147

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers. © 2019 The Author(s). Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers mutual effect of corrosion environment, mech nical tresses and hyd ate formation were deter ined. A change in corrosion mechanism in chloride media t incr asi g chloride concentratio from 2.5 mol/L to high r concentration was found. Th revealed mor sig ficant fluence of m chanical stress on localized corrosion rate than o uniform corrosion one was associated with th formation of local galvanic elements on the metal sur ace an intensification of the metal dissolution in the tensile zone due t th weak ning f interatomic interaction c u ed by increase the distance between grains. Fatigu tests of the pipe steel specimens after exposure to gas t showed a significant decrease in durability (by 15 – 25% depending on test environment), the reason of which was obviously associated with increasing of corrosion damaging of the specimen surface as a result of t e aggressive action of gas hydrates. © 2019 The Author(s). Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” Influence of the gas hydrates on the corrosion rate of gas gathering pipelines Lubomyr Poberezhny*, Andrii Hrysanchuk, Halyna Grytsuliak Ivano-Frankivsk National Technical University of Oil and Gas,15 Karpatska St,. Ivano-Frankivsk 76019, Ukraine Abstract The regularities of corrosion degradation of the low carbon ferrite pearlite St 20 (0.2C) steel of gas gathering pipeline under the mutual effect of corrosion environment, mechanical stresses and hydrate formation were determined. A change in corrosion mechanism in chloride media at increasing chloride concentration from 2.5 mol/L to higher concentration was found. The revealed more significant influence of mechanical stress on localized corrosion rate than on uniform corrosion one was associated with the formation of local galvanic elements on the metal surface and intensification of the metal dissolution in the tensile zone due to the weakening of interatomic interaction caused by increase the distance between grains. Fatigue tests of the pipe steel specimens after exposure to gas hydrate showed a significant decrease in durability (by 15 – 25% depending on test environment), the reason of which was obviously associated with increasing of corrosion damaging of the specimen surface as a result of the aggressive action of gas hydrates. 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” Influence of the gas hydrates on the corrosion rate of gas gathering pipelines Lubomyr Poberezhny*, Andrii Hrysanchuk, Halyna Grytsuliak Ivano-Frankivsk National Technical University of Oil and Gas,15 Karpatska St,. Ivano-Frankivsk 76019, Ukraine Abstract The regularities of corrosion degradation of the w carbon fer ite pea lite St 20 (0.2C) steel of gas gathering pipeline er t Keywords : corrosion; mechanical stress; fatigue; hydrate formation, field pipeline

Keywords : corrosion; mechanical stress; fatigue; hydrate formation, field pipeline

1. Introduction 1. Introduction

Hydrates can easily influence various types of internal corrosion of gas pipelines. This corrosion refers to pitting corrosion, which is often observed both in neutral and acidic environments. This type of corrosion is very difficult to Hydrates can easily influence various types of internal corrosion of gas pipelines. This corrosion refers to pitting corrosion, which is often observed both in neutral and acidic environments. This type of corrosion is very difficult to

* Corresponding author. Tel.: +380-342-72-7173; fax: +380-342-54-7139. E-mail address: lubomyrpoberezhny@gmail.com

2452-3216 © 2019 The Author(s). Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers 2452-3216 © 2019 The Author(s). Published by Elsevier B.V. Peer- review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers * Corresponding author. Tel.: +380-342-72-7173; fax: +380-342-54-7139. E-mail address: lubomyrpoberezhny@gmail.com

2452-3216  2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the 6th International Conference “Fracture Mechanics of Materials and Structural Integrity” organizers. 10.1016/j.prostr.2019.07.033