Title : Magnetic Gradient Tomography Method (MTM-G), Next MTM generation of assessing the integrity of difficult-to-inspect pipelines
Abstract:
This paper describes an innovation in the Magnetic Tomography Method (MTM), which is an improve on the previous approach and technology. The principles and approach about assessing pipeline integrity remain the same, especially for pipes that are non-piggable and difficult to inspect using other methods. The particular innovations are concentrated on the evaluation on the potential of the new technology in terms of the best compliances with market demands. A new generation of technology known as Magnetic Gradient Tomography Method (MTM-G) has been developed, with the key point being the ability to classify mechanical stresses by types into hoop, longitudinal, and other any various complex combinations (bending, twisted, shear stresses, and so on). MTM-G is outfitted with a new gradient sensor topology, new sensitivity grades, and additional application of signal processing techniques that will increase the confidence level of providing contactless inspection data. As a result, MTM-G technology and approach can directly recognize the signal from various types and sources of stresses as the shape of its magnetic response allows for more accurate assessment of the pipeline's behaviour under actual stress conditions caused either by locally concentrated defects and clusters or by a general stress-deformed state. The MTM-G approach and technology have been designed to more clearly delineate the areas characterizing the changing of hoop parts of mechanical stresses that will determine the operating modes of pipelines in a pressure term and longitudinal part that will affect the operation of subsea pipelines with variable underwater currents, areas with unstable soil, sudden soil movements, and areas with a significant impact of temperature changes.
With MTM-G, the approach and technology have broadened the applications of existing technologies. The technological breakthrough is intended to assist asset owners who want to discover more about their pipeline's behaviour and true state under in-situ operation conditions. On the other hand, the new approach and technology retain all of the benefits of non-contact external inspection, examining the actual state of the pipeline and evaluating risk as well as prognosis with greater reliability and confidence.
