Finite element modelling of a circumferential magnetiser

Pipeline integrity is vital and should be maintained through regular inspection. A popular inspection technique is magnetic flux leakage (MFL) where an in-line inspection (ILI) tool magnetically saturates the pipeline locally as it traverses the pipe inner bore. Pipe defects cause magnetic flux patterns to change and this change is detected by a set of magnetic sensors mounted on the tool. For the MFL technique to be optimised, magnetic saturation in the pipe material is required. This paper examines finite element (FE) simulations in which a section of line pipe is magnetised along its circumference under both static and moving tool conditions. Early findings are reported that highlight difficulties associated with maintaining a stable magnetic circuit for a moving ILI tool. The results provide insights into the design considerations and challenges of employing circumferential MFL tools and their associated sensors.