Time-of-flight diffraction ultrasonics

About: Time-of-flight diffraction ultrasonics is a(n) research topic. Over the lifetime, 544 publication(s) have been published within this topic receiving 3189 citation(s).

Reliability of non-destructive test techniques in the inspection of pipelines used in the oil industry

Abstract: The aim of this work is to evaluate the reliability of non-destructive test (NDT) techniques for the inspection of pipeline welds employed in the petroleum industry. Radiography, manual and automatic ultrasonic techniques using pulse-echo and time of flight diffraction (TOFD) were employed. Three classes of defects were analyzed: lack of penetration (LP), lack of fusion (LF) and undercut (UC). The tests were carried out on specimen made from pipelines containing defects, which had been artificially inserted on laying the weld bead. The results showed the superiority of the automatic ultrasonic tests for defect detection compared with the manual ultrasonic and radiographic tests. Additionally, artificial neural networks (ANN) were used in the detection and automatic classification of the defects.

Crack detection and sizing technique by ultrasonic and electromagnetic methods

Abstract: Improvements in defect detection and sizing capabilities for non-destructive inspection techniques have been required in order to ensure the reliable operation and life extension of nuclear power plants. For the volumetric inspection, the phased array UT technique has superior capabilities for beam steering and focusing to objective regions, and real-time B-scan imaging without mechanical scanning. In contrast to the conventional UT method, high-speed inspection is realized by the unique feature of the phased array technique. A 256-channel array system has developed for the inspection of weldment of BWR internal components such as core shrouds. The TOFD crack sizing technique also can be applied using this system. For the surface inspection, potential drop techniques and eddy current techniques have been improved, which combined the theoretical analysis. These techniques have the crack sizing capability for surface breaking cracks to which UT method is difficult to apply. This paper provides the recent progress of these phased array and electromagnetic inspection techniques.

Finite Element Analysis Model on Ultrasonic Phased Array Technique for Material Defect Time of Flight Diffraction Detection

Abstract: In this study, the finite element method (FEM) for phased array technology in ultrasonic time of flight diffraction (TOFD) for the defect detection of two-dimensional (2-D) geometric materials was researched. The phased array technology generated the FEM model for the TOFD signal. We have established the finite element model by the FEM software ANSYS based on the ultrasonic mechanism about the defects and the phased array transducer. A plane strain elements have simulated the reflected signal of the defect. We can compare the error ratio between simulation and experiment by using the theoretical calculation value as the benchmark, and find the feasibility of the FEM detection.

A laser–EMAT system for ultrasonic weld inspection

Abstract: Non-destructive testing of welded metal components is an area where significant cost savings can be made if preparation costs can be minimised. The largest cost associated with preparation is grinding off the weld cap in order to facilitate the detection of defects that may be present just under the cap. In addition, there are also potential savings to be made if the actual testing time can be reduced or if the tests can be performed at elevated temperatures beyond which conventional contacting ultrasonic techniques can be practically used. This paper describes a non-contacting NDT method using a pulsed laser and an electromagnetic acoustic transducer (EMAT) which has the potential to interrogate the entire cross-section of a weld.