University of Illinois Urbana-Champaign

Fatigue crack growth in hydrogen pipeline steels

Che, Ziwei

Content Files
CHE-THESIS-2018.pdf

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https://hdl.handle.net/2142/101584

Description

Title
Fatigue crack growth in hydrogen pipeline steels
Author(s)
Che, Ziwei
Issue Date
2018-07-17
Director of Research (if dissertation) or Advisor (if thesis)
  • Sofronis, Petros
  • Dadfarnia, Mohsen
Department of Study
Mechanical Sci & Engineering
Discipline
Mechanical Engineering
Degree Granting Institution
University of Illinois at Urbana-Champaign
Degree Name
M.S.
Degree Level
Thesis
Date of Ingest
2018-09-27T16:17:52Z
Keyword(s)
fatigue, API steel, stress intensity factor
Abstract
Pipeline hydrogen transport and distribution are contemplated for hydrogen applications. Hydrogen introduction in the natural gas pipeline systems is also considered in the power to gas (P2G) approach to utilizing excess renewable energy when the supply exceeds the demand. It is well known that hydrogen embrittles all carbon steels used to manufacture pipelines and hence, safety and reliability of hydrogen transport requires that pipelines be assessed and tested against hydrogen embrittlement. The most severe embrittlement mechanism is hydrogen accelerated fatigue crack growth since it is well known that hydrogen can enhance fatigue crack growth rates by a factor of 10. In this thesis, the fatigue life of a line pipe manufactured with API steel is calculated by investigating the growth of a semi-elliptical crack on the inner diameter surface due to hydrogen pressure fluctuation. This behavior is compared with the life of the line pipe in an inert environment (e.g. natural gas or N2) under the same pressure fluctuations. The hydrogen or the inert environment pressure history is analyzed with the rainflow counting method and the crack depth calculations are carried out for a variety of API steels at load ratios for a given initial crack depth. The load ratio R equals where and are respectively the minimum and maximum stress intensity factors in a pressure cycle the crack experiences due to the pressure fluctuations. In particular for API X42 steel for which experimental data are available for calculations with greater load ratio, the fatigue life is calculated at load ratios and . The calculation of the stress intensity factor was done by using the closed form solution of Zahoor for which the validity range with regard to the crack and line pipe dimensions was established through comparisons with numerical calculations. The results demonstrate that hydrogen markedly accelerates crack growth and the initial crack depth has significant effect on the pipeline life.
Graduation Semester
2018-08
Type of Resource
text
Permalink
http://hdl.handle.net/2142/101584
Copyright and License Information
Copyright 2018 Ziwei Che

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