Circumferential guided wave EMAT system for pipeline screening using shear horizontal ultrasound

Abstract

The use of guided waves is now widespread in industrial NDT for locating metal loss in pipelines, that manifests as pitting, corrosion and general wall thinning. In this paper, a screening technique is assessed in terms of defect detection and defect sizing capability.Shear Horizontal (SH) guided waves propagate circumferentially around the pipe whilst the scanner is moved axially along the length. This type of tool is preferable to other methods, being applied to the exterior of the pipe, without requiring full circumferential access, and is able to operate through thin coatings (up to 1 mm thick). It is designed to provide a pipe screening tool for petrochemical pipelines both topside and subsea, particularly for detecting defects at pipe support areas. The system's efficacy in terms of detection and sizing of defects is considered via experimental measurements on artificially induced defects and in service corrosion patches, with results compared to finite element modelling of the interaction of the guided waves with artificial defects. Finite element modelling has 2 been used to better understand the behaviour of different wave modes when they interact with defects, focusing on the mode conversions and reflections that occur.

Pipeline Health Monitoring to Optimise Plant Efficiency

“…There are several transduction technologies for generation and detection of UGW including electromagnetic acoustic transducers (EMATs) [33], piezocomposite transducers, magnetostrictive devices [34], lasers and the most commercially used piezoelectric transducers.…”

Characteristics of T(0, 1) Guided-Wave Point-Focusing Electromagnetic Acoustic Transducer for Pipe Inspection

“…The primary means of NDT include: ultrasonic testing [6], magnetic flux leakage testing [7], eddy current testing [8], radiation testing in medical treatment [9], and optical fiber for long-term strain detection for buildings [10]. Among these methods, ultrasonic testing, particularly with guided-wave technology, is widely used in industrial testing to detect defects in thin-walled plates and pipes [11][12][13]. As a sound detection technology, ultrasonic guidedwaves can travel very far along a pipe with little attenuation, and offer a clear directionality in the propagation process, so that defects in the specimen at various positions along the guidedwave propagation path can be detected [14].…”

In-line inspection of unpiggable buried live gas pipes using circumferential EMAT guided waves

“…Guided wave has been widely used for NDE applications 1 . For pipeline NDE, two types of guided waves are usually employed, namely axial waves [2][3][4][5][6][7][8] and circumferential waves [9][10][11][12][13][14] . Axial wave method usually requires access to a "ring" shape section of the pipe.…”