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Time of Flight Diffraction (TOFD) Level 2

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. TOFD has also become the most accurate and effective Non-Destructive Testing (NDT) technique in determining defect height. Time of Flight Diffraction has significant advantages regarding safety, required time of inspection, and 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. This course is designed to take the advanced NDT technician through the Time of Flight Diffraction Technique and its ability to perform flaw detection, location and sizing. Considerable time is spent in the collection and analysis of Time of Flight Diffraction data and the comparison to traditional Pulse -Echo technique.

We can provide TOFD Training courses and examinations suitable for the following certification scheme.

  • PCN/SNT-TC-1A/NAS 410 - EN 4179.

We can also provide training for PCN/SNT-TC-1A/NAS 410 – EN 4179 NDT Level 3.

An example of the syllabus that is used for TOFD training courses is shown below for Level 2. Decibel can tailor make the syllabus to satisfy the requirements of an individual’s company specific written practice if requested.

Key Syllabus Topics - Level II

Fundamentals of TOFD

  • Principles of TOFD and the Diffraction Process.
  • Basic TOFD set up and types of scans.
  • Digitization of the Analogue Ultrasonic Signals.
  • Data collected during an Inspection.
  • Grey scale imaging and B-scans.
  • Analysis and Off-line Facilities.
  • Precision and Resolution.
  • Beam Spread Considerations and basics for Calculation of Beam Spread.
  • Example of Selection of Number of Scans for an Inspection.
  • Choice of Probe Angle.
  • Transducer size and frequency.
  • Choice of Probe Centre Separation.
  • Calibration of Setting of Gain.
  • Flaw Sizing with the Pulse Echo Technique.
  • Comparison of Flaw Sizing Accuracy for Different Techniques.
  • Angular Variation of Diffraction Signals.
  • Effect of Change in PCS and Importance of Calibration with Lateral and Back Wall signals
  • Error due to Variations in Couplant Depth, Surface Profile and Velocity Error.
  • Index Point Migration Errors and other cumulative errors.

Data collection and basic interpretation

  • Manual, encoded parallel and non-parallel scans
  • Encoder calibrations
  • Storage, manipulation and interpretation of data
  • Basic Interpretation

Key Benefits

  • The technician should leave the course with a sound understanding of the TOFD process.
  • The technician will be able to carry out basic operations functions, including calibration, detection and identification of indications.
  • The technician, with dedicated application will be able to apply code compliant examinations to welded components.

Qualification Required

Candidates with good knowledge over Ultrasonic Testing & its application may enroll towards this program, if the interested candidates doesn’t have enough knowledge over Ultrasonic Testing and it’s practical application, those candidates may initially enroll towards Practical Ultrasonic Testing/ Specialization in A- Scan UT program conducted at Decibel and after that they can enroll towards this program.

About Qualification

For PCN: Refer PCN General Requirements Document

For NAS410/EN4179/SNT-TC-1A: According to Written Practice.

For ACCP: Refer ACCP General Requirements Document

Course Duration:

Will vary depends on the type of certification chosen

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