Ultrasonic TOFD Method Application for Steel Components and Welds of 10mm Wall Thickness Using Ultrasonic Flaw Detector and ULTRA7 TOFD Software

摘要

Pressure Vessels inspection is carried out using complex of NDT techniques. A relatively recent technique ultrasonic NDT, is the Time-of-Flight Diffraction (TOFD) method as an effective method for detection and sizing of flaws. One of the way inspection heavy duty steel elements and welds is to use manual TOFD technique with longitudinal waves at refracted angles of 45 to 70 degrees. Typically inspections using this method have been on steel elements and welds varying from 12 mm to 300 mm wall thickness. In this paper is presented examples of using the TOFD techniques for 10mm wall thickness using USM 35XS and ULTRA7 TOFD software. This software provides TOFD inspection design (PCS, sound path, beam coverage, dead zones) and validation services. The calculations of the two dead zones are derived from relatively trigonometric equation, graphically displayed on a PC-screen and weld frame form. Using ULTRA-7TOFD the user must move the gate at which the flaw is located on PC-screen to determine the depth of defect. The diffraction points graphically displayed in a weld frame form and analyzed using geometry calculations.