Issue 59

J.L. González -Velázquez et alii, Frattura ed Integrità Strutturale, 59 (2022) 105-114; DOI: 10.3221/IGF-ESIS.59.08

Focussed on Fracture and Structural Integrity

On the Assessment of non-metallic inclusions by part 13 of API 579 -1/ASME FFS-1 2016

Jorge Luis González-Velázquez, Ehsan Entezari Department of Metallurgy and Materials, Escuela Superior de Ingeniería Química e Industrias Extractivas, Instituto Politécnico Nacional, Mexico jlgonzalezv@ipn.mx, https://orcid.org/0000-0001-6914-4449 ehsan.entezari2014@gmail.com, https://orcid.org/0000-0003-3379-1761 Jerzy A. Szpunar Department of Mechanical Engineering, University of Saskatchewan, Canada jerzy.szpunar@usask.ca, https://orcid.org/0000-0002-1291-8375

A BSTRACT . Improvement of non-destructive inspection techniques has allowed more frequent detection of closely spaced zones of non-metallic inclusions in pressure vessels made of low carbon steel. In the present study, closely spaced inclusions in an in-service cylindrical horizontal pressure vessel were detected by Scan-C ultrasonic inspection and considered as laminations to be assessed by Part 13 of the API 579-1/ASME FFS-1 2016 standard. The outcoming results were considered as a rejection for Level 1 assessment, and a repair or replacement of the component was required, even though it retained a significant remaining strength. Thus, an alternative procedure to assess the mechanical integrity of pressure vessels containing zones of non- metallic inclusions is proposed by adopting some criteria of the API 579- 1/ASME FFS-1 Part 13 standard procedure and taking into consideration the dimensions and grouping characteristics of the inclusion zones. K EYWORDS . Structural integrity assessment; Non-metallic inclusions Ultrasonic inspection; Pressure vessel.

Citation: González-Velázquez, J.L., Entezari, E., Szpunar, J.A., Assessment of non-metallic inclusions by part 13 of API 579 -1/ASME FFS-1 2016, Frattura ed Integrità Strutturale, 59 (2022) 105-114.

Received: 28.08.2021 Accepted: 15.10.2021 Published: 01.01.2022

Copyright: © 2022 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.

I NTRODUCTION

he presence of non-metallic inclusions (NMIs) in the shell and heads of pressure vessels made of low carbon steel exposed to sour environments in the oil and gas industries is one of the main factors to increase the susceptibility of hydrogen-induced cracking (HIC). According to Gonzalez-Velazquez [1], the interface between the NMIs and the steel matrix is the preferred site for hydrogen trapping and nucleate HIC. Accordingly, the hydrogen originated from hydrogen sulfide (H 2 S) and atmospheric moisture traps at the interface between steel matrix and NMIs, increasing molecular hydrogen pressure [2-4]. High molecular hydrogen pressure separates the metallic matrix and inclusions, causing propagation T

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