High strength and low alloy steels are used as an effective material for pipeline systems operating at high pressure and flow with reduced weight and cost. But conditions of the marine environment, such as the corrosive environment, requires the use of special protection. Non-conductive coatings are used in pipelines throughout the oil and gas industry for a variety of applications including corrosion protection. Being able to inspect through coating layers is, therefore, important for quality control and structural integrity assessments. However, most characteristically non-destructive evaluation (NDE) method become ineffective in such applications. Due to lift off variation, eddy current sensors can be used to detect flaws underneath the coating. Lift off is the term used to denote the impedance change that occurs when there is variation in the distance between the inspection coil and the specimen. On the other hand, lift off could occur in the same direction as the flaw, canceling the flaw response, and this may be an inconvenience to the application of the technique in some locations. One instrument which enable to reduce this undesirable effect is the Meandering Winding Magnetometer (MWM). This is a multifrequency instrument capable of determining the level of degradation of the oxidation/corrosion, as well as the detection of cracks, even under coating layers. In this paper, a two-dimensional (2-D) and a three-dimensional (3-D) finite element model is described for non-destructive evaluation applications without removing coatings or insulation that directly compute the electromagnetic field disturbance due to sensor arrangements (using inductive sensor elements) with high frequencies and models based on pre-computed databases to determine the properties of the pipeline and the damage profilometry. A composite grid method was applied in the analysis of the electromagnetic field penetration of eddy currents. The optimization of the parameters was performed using COMSOL Multiphysics® 5.4 finite element modeling (MEF) software in "2D asymmetric" and "3D" sessions. Lastly, the results of the simulation in three dimensions were compare with the results obtained through the experimental arrangement using MWM technology.
展开▼
