The presence of hard spot in pipelines, a localized confined region of relatively higher hardness, are prone to crack initiation and hydrogen embrittlement. Early detection of hard spots before it can be an integrity threat is an essential part of integrity management plan for pipelines susceptible to hard spot related failures. Electromagnetic principles and its dependence on the microstructure, heat treatment and chemistry are used effectively for hard spots characterization. The ability to detect shallow hard spots is essential for thermo-mechanically heat treated steel....
The presence of hard spot in pipelines, a localized confined region of relatively higher hardness, are prone to crack initiation and hydrogen embrittlement. Early detection of hard spots before it can be an integrity threat is an essential part of integrity management plan for pipelines susceptible to hard spot related failures. Electromagnetic principles and its dependence on the microstructure, heat treatment and chemistry are used effectively for hard spots characterization. The ability to detect shallow hard spots is essential for thermo-mechanically heat treated steel. It is unclear whether there are commercial tools that are effective, and no quantitative data is available. A holistic review of the existing and emerging technologies and their theoretical basis for the hard spot detection and their applicability to pipelines is indeed needed. This work reviews the electromagnetic principles that are applicable for hard spot detection/discrimination, and the applicable technologies that are either developed or being developed by various global NDE suppliers. Four different technologies have been identified for further examination during Phase II. The intent would be to quantify the detection/discrimination and characterization capabilities of each of these technologies. Selected providers have a unique way of hard spot identification and it would be very beneficial to compare their performance in the phase-II of this project. Inspection approaches, their key principles and their latest development are presented in this report.