Received wisdom regarding guidelines of boiler tube thickness evaluation, specifies 70% wall thickness as the flag point below which the tube should be replaced. The aim of this work is to investigate the feasibility of remote field testing (RFT) method in the inspection of ferromagnetic materials and demonstrate its limitations, in the timely and reliable detection of boiler tube defects, using conventional commercial probes. The impact of excitation frequency and channel bandwidth on defect amplitude, phase, defect sizing and material permeability are analysed. Samples of ASTM A179 and ASTM A 106 carbon steel tubes having artificial discontinuities were studied. The response of RFT inspection to various defects was measured, as was the sensitivity to defect size. Experimental results show that small size defects like porosity, fatigue crack and axial oriented cracks may present unfavourable conditions for early defect detection in boiler tubes. Based on the experimental setup used, RFT may reliably detect discontinuities greater than 4mm diameter with up to 40% diminution. However, it may be challenging to detect defects occurring close to boiler tube sheet.
|Publication status||Accepted/In press - 13 Jun 2018|
|Event||International Conference on Robotics, Automation and Non-Destructive Evaluation - Chennai, India|
Duration: 3 Jan 0001 → …
|Conference||International Conference on Robotics, Automation and Non-Destructive Evaluation|
|Period||3/01/01 → …|