Abstract
This paper aims to provide an overview of the experimental and simulation works focused on the detection, localisation and assessment of various defects in pipes by applying fast-screening guided ultrasonic wave techniques that have been used in the oil and gas industries over the past 20 years. Major emphasis is placed on limitations, capabilities, defect detection in coated buried pipes under pressure and corrosion monitoring using different commercial guided wave (GW) systems, approaches to simulation techniques such as the finite element method (FEM), wave mode selection, excitation and collection, GW attenuation, signal processing and different types of GW transducers. The effects of defect parameters on reflection coefficients are also discussed in terms of different simulation studies and experimental verifications.
Highlights
Industrial pipeline systems are commonly used to transport oil, gas and petrochemical products
The interesting part is that the peak of the reflection coefficient (RC) for defects including low axial extents, such as cracks, is less than that for defects, such as corrosion patches, when the axial extent makes up a significant portion of the wavelength and can be observed to be less complicated than cracks
The improved test methodology is summarised in three steps: (1) performing unfocused long-range ultrasonic testing (LRUT) applying axisymmetric wave modes and using improved methods for showing the results to detect regions of interest, (2) performing an inspection using the phased array flexural mode focusing technique at axial locations specified by the data obtained using Step 1 and (3) combining the angular distribution data obtained using Step 2 and the amplitude data from the normal inspection technique to provide a classification of defect severity [95]
Summary
Industrial pipeline systems are commonly used to transport oil, gas and petrochemical products (e.g., corrosive substances). The locations of internal and external defects in the pipe wall are identified by their are identified by their reflection arrival time. A systematic analysis of frequency, guided wave mode, defect size and pipe size on the RC from notches was presented. Circumferential extent, depth and location of various shaped defects were studied by focusing on 44 circumferential locations around the pipes at a particular distance and the maximum amplitude of the defect signal obtained for each circumferential focal position. The amplitude factors and time delay for GW array focusing were nonlinear functions of the active frequency, excitation condition, pipe size and focal distance. To discuss and compare two focusing techniques that can increase defect detectability by focusing the UGWs by transducer arrays (1) SBF focused UGWs by employing cross-correlation analysis. At a provided maximum depth of a finite defect, the RC peak from defects was a linear function of the circumferential length of the defects and was independent of their shapes
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