Oil-Tank Weld Detection Using EMAT

Abstract

Tanks are typically used for the storage of oil by the petrochemical industry, and the storage quality is largely determined by the safety of the equipment. Recently, Electromagnetic Acoustic Transducer (EMAT) technology has been the focus of many non-destructive examinations, as EMATs can generate elastic waves without contact, thereby making it easy to carry out the process of detection. The Shear Horizontal (SH)-guided waves that are generated by an EMAT are modeled in a plate made of ferromagnetic material, and this is of particular interest regarding the testing of welded structures. This paper provides an EMAT-sensor design that can be used to find cracks in the welds of a tank whereby the need for people to climb onto the tank is removed; furthermore, regarding cases where the amplitude signal of the SH-wave EMATs is too low, a simulation is used in this paper to propose a method that improves the transduction efficiency.

Development of an MFL Coil Sensor for Testing Pipes in Extreme Temperature Conditions

“…Urayama et al [ 25 ] have developed and tested a dual Electro-Magnetic Acoustic Transducer (EMAT)/EC probe for monitoring pipe wall thinning at high temperatures (300 °C). It is a non-contact defect detection technique [ 26 ] that uses laser-generated ultrasound [ 27 ] where an array of EMATs is used for crack detection using lamb waves, and a qualitative model is developed for the laser-generated transient ultrasonic lamb waves in orthographic thin plates [ 28 , 29 ]. This technique, however, cannot be used to detect corrosion.…”

A Hybrid Ultrasonic Guided Wave-Fiber Optic System for Flaw Detection in Pipe

“…This technique is responsible for amazingly fast inspection of corrosion type defects in large plate-like structures employing radar type circumferential or sector scans. Other NDT applications for guided waves, for example, include oil-tank weld detection using EMAT-generated shear-horizontal guided waves [14] 2017, fundamental torsional mode detection of angled cut flaws [15] 2016, and liquid level displacement measurements using magnetostrictive sensors [16] 2017.…”