NDT – Time of Flight Diffraction Training Courses

TOFD History and Development

Time of flight diffraction (TOFD) is an Ultrasonic Testing Technique originally developed to increase the sizing accuracy of flaws previously detected by conventional NDT techniques.

In recent years, not only technology and software have advanced, but also the usefulness of Time of Flight Diffraction. Unlike a few years ago, Time of Flight Diffraction is now the most important of all NDT methods for the detection of flaws. and not just for its accuracy in sizing.

Due to insufficient knowledge about the application of this new technology, flaws remained undetected, causing a general lack of confidence in the TOFD application. Many years passed with several industrial trials and validations being conducted, until finally a stage was reached where Time of Flight Diffraction has become an essential tool in the ultrasonic toolbox.

Today, TOFD is accepted worldwide, and in many cases, it has replaced onsite radiography as TOFD has strong advantages regarding safety, required time of inspection, and costs. As this technique is increasingly applied globally, it is essential to educate practitioners about its correct and incorrect use and interpretation.

Time of Flight Diffraction Training

SGS Training & Examination Center is a BINDT Accredited Training Organization (ATO) and an Authorized Qualifying Body (AQB) for TOFD. Moreover, SGS is qualified to conduct both the required pre-examination training and the PCN examinations for Levels 1, 2 and 3.

SGS Training Policy

To be eligible for the TOFD training course, the candidates must first successfully pass the Ultrasonic Testing Course. The TOFD course is particularly suitable for UT Level 2 NDT operators.

The theory is carefully explained to enable the average NDT practitioner to comprehend all aspects of the training. Use of the latest techniques and visual aids, such as animated presentation material, together with video projection of instrument displays, enhance the learning experience and enable students to absorb the volume of information.

The SGS Training and Examination Center provides a range of welded samples suitable for TOFD inspection, including flat-butt welded plates, pre-cut sections, butt welded pipes and butt welded T-sections. These samples range from 10mm to 50mm thick, with flaws representative of those that may be found in the industry. All samples meet the requirements of BINDT/PCN/EN473 criteria for TOFD training.

The tutors explain the equipment and software by the process of demonstration both for set-up prior to data acquisition, and analysis post-data acquisition. The candidates learn about the process of equipment calibration and the adjustment of the correct parameters for the tests. Upon completion of data acquisition, data analysis and post-data acquisition procedures will be demonstrated and discussed with the students.

Candidates are then encouraged to practice the data analysis procedures themselves by using a comprehensive range of scanned files, which contain a broad spectrum of pre-service and in-service flaws.

Throughout the duration of the training, practical experiments and continuous assessments are conducted to monitor the candidate’s progress and understanding.

All levels of Time of Flight Diffraction training and examinations include data acquisition. Moreover, Level 2 candidates are required to produce an NDT written instruction for a Level 1 candidate to follow for data acquisition on a particular sample. Level 3 candidates, meanwhile, are required to create a procedure, which includes a complete inspection technique.