An Eddy Current Testing Platform System for Pipe Defect Inspection Based on an Optimized Eddy Current Technique Probe Design

Abstract

The use of the eddy current technique (ECT) for the non-destructive testing of conducting materials has become increasingly important in the past few years. The use of the non-destructive ECT plays a key role in the ensuring the safety and integrity of the large industrial structures such as oil and gas pipelines. This paper introduce a novel ECT probe design integrated with the distributed ECT inspection system (DSECT) use for crack inspection on inner ferromagnetic pipes. The system consists of an array of giant magneto-resistive (GMR) sensors, a pneumatic system, a rotating magnetic field excitation source and a host PC acting as the data analysis center. Probe design parameters, namely probe diameter, an excitation coil and the number of GMR sensors in the array sensor is optimized using numerical optimization based on the desirability approach. The main benefits of DSECT can be seen in terms of its modularity and flexibility for the use of different types of magnetic transducers/sensors, and signals of a different nature with either digital or analog outputs, making it suited for the ECT probe design using an array of GMR magnetic sensors. A real-time application of the DSECT distributed system for ECT inspection can be exploited for the inspection of 70 mm carbon steel pipe. In order to predict the axial and circumference defect detection, a mathematical model is developed based on the technique known as response surface methodology (RSM). The inspection results of a carbon steel pipe sample with artificial defects indicate that the system design is highly efficient.

Investigate the effect of lift-off on eddy current signal for carbon steel plate

“…Effect of factors with central points and corresponded interactions was investigated by perturbation plots and response surface plots respectively. F ratio for the models ascertained less than 0.05 to ensure the fitting model reflects and appropriate for response prediction to the system [9].…”

“…Although, lowering of excitation frequency enhances the depth of penetration of eddy currents [8]. However the ECT methods detect variations in the magnetic field using coil which are fundamentally limited by their poor sensitivity at low frequencies weak strength of the magnetic fields limits the detection sensitivity of coils for deep flaws (>5.0 mm) [9]. At significant lift-off, no detectable emf will be induced in the secondary coil due to the sample [10,11].…”

Review of Pulsed-Eddy-Current Signal Feature-Extraction Methods for Conductive Ferromagnetic Material-Thickness Quantification

“…While several techniques have been investigated for defect and crack detection of conductive materials [4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], when it comes to thickness quantification of conductive ferromagnetic materials, the Pulsed Eddy Current (PEC) technique, especially the detector coil-based PEC sensor architecture, has been commonly used [21][22][23][24]. The main reason for this associated with detector coil-based PEC sensors can be identified as it being possible to extract signal features that are proportional to the diffusion time constant of eddy currents [23] induced inside a ferromagnetic wall-like structure, and this diffusion time constant behaving as a function of the wall thickness [23].…”

A High Signal–Noise Ratio UWB Radar for Buried Pipe Location Using Golay Complementary Sequences

“…Once the buried pipes are damaged, the undesirable fluid losses due to leaks can cause enormous environmental and economic repercussions. Ultra-wideband (UWB) ground penetrating radar (GPR) [1][2][3] as one of the non-destructive techniques [4][5][6][7][8] to locate the underground pipes attracts increasing attention because it is capable of accurately locating both metallic and non-metallic pipes without prior knowledge. However, conventional UWB GPR utilizes short pulse as the transmit signals, which leads to a tradeoff between the resolution and the detection distance.…”