论文信息 - Effects of stress on MFL responses from elongated corrosion pits in pipeline steel

Effects of stress on MFL responses from elongated corrosion pits in pipeline steel

A hydraulic pressure vessel simulation of an operational length of pipeline was constructed to investigate the effects of line pressure stress conditions on Magnetic Flux Leakage (MFL) signals from elongated corrosion pits in API X70 steel line pipe. Two axially elongated corrosion pits were electrochemically milled into the pipe at different circumferential stress levels. Axially excited radial MFL fields were measured. The behaviour of both individual measurements and data trends were correlated with magnetic Barkhausen noise measurements around the perimeter of each defect. Results differ between the defect milled without an applied stress and the defect milled under an applied circumferential tension of 220 MPa. This indicates the need to account for the ambient stress conditions during defect formation in any MFL tool calibration technique.

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