Abstract

Pipelines are the primary means of land transportation of oil and gas globally and pipeline integrity; is therefore, of high importance. Failures in pipelines may occur due to internal and external stresses that produce stress concentration zones, which may cause failure by stress corrosion cracking. Early detection of stress concentration zones could facilitate identification of potential failure sites. Conventional non-destructive testing (NDT) methods, such as magnetic flux leakage, have been used to detect defects in pipelines; however, these methods cannot be effectively used to detect zones of stress concentration. In addition, these methods require direct contact, with access to the buried pipe. Metal magnetic memory (MMM) is an emerging technology, which has potential to characterize stress state of underground pipelines from above ground. The present paper describes magnetic measurements performed on steel components, such as bars and tubes, which have undergone changing stress conditions. It was observed that plastic deformation resulted in modification of measured residual magnetization in steels. In addition, an exponential decrease of signal with distance of the sensor from the sample was observed. Results are attributed to changes in the local magnetic domain structure in the presence of stress, but in the absence of an applied field.

How to Cite:

Saleem, A., Underhill, P. & Krause, T., (2019) “Non-contact magnetic characterization of steel structures”, Review of Progress in Quantitative Nondestructive Evaluation .