Session: CS-02-01 Hydrogen Effects on Material Behavior for Structural Integrity Assessment-Assessment of Pipelines

Paper Number: 123584

123584 - Hydrogen-Assisted Fatigue in Pipeline Steels: Modeling and Risk Assessment 

The increasing demand for energy, as well as the global threat of climate change, has driven the search for alternative energy sources, with hydrogen being widely considered as an alternative to fossil fuels. However, a major concern still exists regarding material degradation under hydrogen, a process known as hydrogen embrittlement. This issue has been under study for decades with no consensus reached. The fatigue behavior of pipeline steels under gaseous hydrogen is a critical problem that is impeding the industry’s adoption of hydrogen into the current infrastructure. Experimental testing suggests an increase in the crack growth rates by over an order of magnitude in different steel grades.

This study focuses on a hydrogen-assisted fatigue crack growth model that depends on the loading conditions such as gas pressure and material variability. The model is benchmarked using the ASME B31.12 code, and probabilistic fatigue life predictions are obtained based on a real-world random loading spectrum using a time-based subcycle fatigue crack growth model. These predictions subsequently aid in risk assessment and risk-based maintenance optimization for gas pipelines. A model demonstration is carried out to identify the synergistic effects of various defects on the reliability of pipeline steels under hydrogen, including welds and surface quality. It is found that the presence of multiple interactive threats greatly affects fatigue reliability. Several future research directions are recommended based on the current findings.

Presenting Author: Kaushik Kethamukkala Arizona State University

Presenting Author Biography: Kaushik Kethamukkala is a second year PhD student in the Department of Mechanical Engineering
at Arizona State University. He is working under the supervision of Dr. Yongming Liu, studying
the effects of gaseous hydrogen on the fatigue behavior of pipeline steels.

Authors:

Kaushik Kethamukkala Arizona State University
Yongming Liu Arizona State University