New Methodologies for Measuring and Monitoring Hydrogen for Safety in Advanced High Strength Line Pipe Steel: Development of a Non-Destructive Non-Contact Electromagnetic Sensor of Hydrogen Content Determination in Coated Line Pipe Steel

摘要

The assessment of the hydrogen content in pipeline steel is an essential requirement to monitor loss of integrity with time and prevent failures. With the 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. Continued accumulation of hydrogen with time will eventually meet the cracking criteria. New and unique methodologies based on electronic property measurements offer the pipeline industry non-destructive tools to achieve this hydrogen content assessment in-situ and in real-time. The use of thermoelectric power, a surface contact non-destructive measurement can assess hydrogen in pipeline steels while the pipe is exposed without coating. A non-contact through-coating technique has also been developed to assess hydrogen through the pipe coating. The induced current low-frequency impedance technique is a cost-effective practice to monitor the hydrogen accumulation in high-strength steel pipelines. This report describes the scientific basis and engineering practice to utilize both of these advanced electronic property measurement techniques. These advanced techniques have been successfully demonstrated to assess hydrogen content in linepipe steel. The practice of determining the equivalent microstructure or steel properties from which standards for hydrogen determination can be produced is also described.