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A. TIME OF FLIGHT DIFFRACTION


Time-of-flight diffraction (TOFD) method of ultrasonic testing is a sensitive and accurate method for the Non Destructive Testing of welds for defects.Time of Flight Diffraction (TOFD), originally developed for crack-sizing in nuclear applications, is an Ultrasonic Testing technique, which established itself as a widely used tool for detecting welding flaws. Measuring the amplitude of reflected signal is a relatively unreliable method of sizing defects because the amplitude strongly depends on the orientation of the crack. Instead of amplitude, TOFD uses the time of flight of an ultrasonic pulse to determine the position of a reflector. TOFD has also become the most effective Non-Destructive Testing (NDT) technique in determining defect height.High-density polyethylene (HDPE) piping has been used in place of steels in the petrochemical, power, and mining industries due to its exceptional resistance to corrosion and erosion. Recently, HDPE has also been used for nuclear safety-related cooling water applications. The application of nuclear quality assurance requirements requires reasonable assurance that the production fusion joint is sound. Ultrasonic time-of-flight-diffraction (TOFD) inspection of fusion joints is an easily employed nondestructive examination tool that can be used to provide additional assurance of fusion-joint integrity. Time of Flight Diffraction has significant advantages regarding safety, required time of inspection, costs and, today is increasingly replacing onsite Radiography. As this technique is being increasingly applied globally, it is essential to educate specialists about its appropriate use and interpretation.

Axionz provide TOFD training courses and certifications.

Topics covered - Level II

The course covers an in depth blend of theory and applied practical work which complement each other to demonstrate what TOFD can and cannot do. Students will be taught how to optimise data acquisition parameters during equipments set-up, plan inspections, understand measurement capabilities and limitations and analyse TOFD data. Data analysis involves a large range of pre-prepared data form samples typically found in industry including corrosion & erosion, original welding process flaws, in-service degradation flaws; fatigue cracking, hydrogen attack pitting and also addresses clad vessel inspections. Course material also includes data recorded from poor set-ups to demonstrate common errors and teach the student to be diagnostic when evaluating images. The objective of this is to enable the data analyst to be competent at instructing data acquisition crews to improve their data for the purpose of more reliable inspections.

Course Content

History of TOFD Development, TOFD Advantages and Limitations, Principles of TOFD, Principles of TOFD, Depth Calculation, Time Calculation, PCS Calculation, Types of TOFD Scan, Equipment Used In TOFD, Digitalization Principles, Equipment Requirements, TOFD Depth, Ring-Time Issues And Errors, Interpretation and Evaluation, Applications

Course Objectives

1.   To explain the theoretical background of the techniques & the TOFD machine characteristics.
2.   To calibrate TOFD equipment (velocity, Wedge delay, Sensitivity, Encoder)
3.   To Scan the plates and acquire the data.
4.   Example of Selection of Number of Scans for an Inspection..
5.   To locate and evaluate defects using TOFD..
6.   To select the correct type of probe/ machine parameters to examine welded butt joints in steel plate..
7.   To report on the location and size of defects in typical welded butt joints..
8.   To interpret code requirements.

Eligiblity Required

Minimum requirement for Candidates:

  • Well experienced in Ultrasonic Testing & its application.

Contact office Course fee and Course duration