PR-186-203813-R02 Pipeline Mid-wall Defect Detection and Fitness for Service Assessment

Hydrogen induced cracking (HIC) within the wall of line pipe is a threat recognized by the pipeline industry; the industry could benefit from a standardize approach to determining threat susceptibility as well as a methodology to estimate the anticipated growth rate of HIC given a set of pipe design, environmental conditions, and operational parameters. The overall objectives of this project were to compile historical literature and references toward understanding HIC as a cracking mechanism and to develop preliminary susceptibility criteria for the threat of HIC. A better understanding of the threat of HIC will reduce product leaks and equipment emissions from all parts of the hydrocarbon transport and storage infrastructure as well as better prepare for the quickly approaching hydrogen economy.

A literature review on the current industry understanding of mid-wall HIC[1] was conducted. A summary of key factors influencing HIC and modern integrity management approaches for the phenomenon are summarized. Based on the literature review, gaps in published industry knowledge were identified.

A literature review was also conducted on the performance of non-destructive examination (NDE) techniques (both in-line and field) and their ability to detect and size mid-wall HIC. A description of the techniques (considering liquid and gas mediums for in-line technologies) and the current understanding of their performance are summarized. Several case studies that were used to assess non-destructive inspection performance are also summarized.

Based upon the current industry understanding of the mid-wall HIC mechanism, as well as the capabilities of NDE technologies, an integrity management framework was developed and is described.

As a result of the literature reviews, case studies, and framework development, a number of gaps in industry knowledge and experience were identified. Most importantly, there is a need for continuous improvement of NDE technologies. Results of the gap analysis should be used to drive work to mitigate the onset of mid-wall HIC and to identify the presence of mid-wall cracking so that the threat can be actively and effectively managed.

[1] The terms mid-wall cracking (MWC) and hydrogen induced cracking (HIC) are synonymous in this report.