Time-of-flight diffraction ultrasonics

About: Time-of-flight diffraction ultrasonics is a research topic. Over the lifetime, 544 publications have been published within this topic receiving 3189 citations.

Laser Ultrasonic Study of Crack Tip Diffraction

Abstract: Ultrasonic diffraction pattern at a crack tip and crack depth sizing based on the diffraction are studied by using laser‐generated bulk waves Directivity patterns oriented essentially along the normal for the diffracted longitudinal wave and essentially at 45 (deg) for the diffracted shear wave for any incident angles is obtained A laser‐ultrasonic system combined with time‐of‐flight (TOFD) analysis is produced and demonstrates accurate crack sizing on an artificial slot having a variable depth from 0 mm to 10 mm An improvement of signal‐to‐noise ratio by split spectrum processing (SSP) is also suggested

Reducing pipeline construction costs: New technologies

Abstract: The Oil and Gas industry is constantly looking for ways to reduce capital investment for new projects while maintaining performance and quality standards. As the demand for oil and natural gas increases, so does the need for an expanded network of onshore and offshore transmission pipelines. However, the capital investment associated with new pipelines is enormous. There are a number of materials joining technologies that are being investigated to reduce pipeline construction costs. This document presents three technologies showing particular promise: laser pipeline welding, the use of high strength pipeline materials, and advanced automatic inspection. Test have shown that the HLAW process, which combines the LBW and GMAW processes, is felt to offer a number of benefits in terms of higher potential productivity, ability to produce welds with excellent material properties and a reasonable tolerance for fit-up variations. For existing laser power levels, a viable scenario for implementation of lasers for pipeline welding applications is the use of HLAW for root bead welding, followed by joint filling with conventional mechanised GMAW-P. Concerning the use of high strength pipeline materials, results of a project are presented. The primary objective of this study was to evaluate the mechanical properties of weld metals deposited using a number of commercially available welding consumables and welding processes. This work included characterization of weld metal microstructure, HAC susceptibility of the GMA weld metal and X100 base metal, and solidification cracking of selected welding consumables. The project evaluated commercially available consumables using several welding processes and shielding gases. The third part of the document covers results of a project aiming to collect third-party independent data and statistically characterise the systematic and random errors in girth weld defect sizing, as measured by mechanised ultrasonic testing P/E, TOFD methods and PA ultrasonic technology, in support of pipeline reliability assessments. The defect sizing accuracy of the automated ultrasonic testing (AUT) of girth welds was evaluated using zonal discrimination with focused and non-focused search units arranged for P/E and TOFD methods and PA technology. The objectives were achieved by conducting “open” and “blind” UT trials. NDE flaw verification and destructive testing for flaw size validation were performed. AUT data were collected and statistically analysed.

Detection of Imperfections in Welded Joints Using the Time-of-Flight-Diffraction Technique (TOFD)

Abstract: The paper presents the results of research on an ultrasonic testing technique known as the time-of-flight-diffraction (TOFD) technique. The research-related tests involved a 10 mm thick MMA welded butt joint containing imperfections in the form of linear slag inclusions. The paper contains TOFD images obtained by scanning the face and the root side of the weld. The TOFD examination results were compared with the results of micro and macroscopic metallographic examinations performed at selected points of the welded joint.

In-line inspection using time-of-flight diffraction

Abstract: The authors look at the potential of an alternative NDT technique time-of-flight diffraction (TOFD), to replace the traditional methods of inspecting fabricated tubular components. The disadvantages of conventional ultrasonic and radiographic inspection are outlined and the processes compared with TOFD.