In-Situ Hydrogen Analysis in Weldments: Novel NDE for Weld Inspection

Main Objective

In this program, the Colorado School of Mines and the National Institute of Standards and Technology - Boulder will collaborate in the development of non-destructive technology for weld inspection, assessment, and repair in high strength pipeline steels and their weldments. Advanced sensors will allow the pipe integrity to be frequently or continuously monitored to assure pipeline safety and environmental protection. The research would be further advanced by the characterization of hydrogen in pipeline steel weldments. The characterization of hydrogen content and behavior in high strength steel weldments is timely and important with the introduction of new higher strength steels (e.g. X100, which have higher susceptibility to hydrogen damage) in the pipeline industry.

Public Abstract

The assessment of hydrogen content in pipeline steel weldments is an essential requirement to monitor loss of weld integrity with time and to prevent failures. With use of pipeline steels of increasing strength, the threshold of hydrogen concentration for hydrogen cracking is significantly being reduced. Cathodic protection and corrosion processes both contribute to accumulation of hydrogen as a function of time, which will eventually meet the cracking criteria. New and unique methodologies based on electronic property measurements offer the pipeline industry advanced non-destructive tools to achieve weldment hydrogen content assessment in-situ and in real-time. The use of thermoelectric power, a surface contact non-destructive measurement, has been demonstrated for assessment of hydrogen in pipeline steel weldments while the pipe is exposed without coating. A non-contact induced current low-frequency impedance analysis technique has also been developed to cost-effectively assess hydrogen content in weldments through the pipe coating. In-situ testing of fatigue crack specimens will further advance understanding of the influence of hydrogen in steel. These advanced techniques have been successfully demonstrated to assess hydrogen content in linepipe steel. This proposal will further advance the use of induced current low-frequency impedance measurements to monitor hydrogen content in pipeline steel weldments.

Final Report

DTPH56-07-T-000009 Final Report

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Other Files

Success Story

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Success Story

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