Time of Flight Diffraction

Sonotech can assist you in setting up your non-intrusive inspection (NII) plan, whereby the aim is to keep your production and HSE performance to the highest level by executing non-intrusive non-destructive testing while the plant is in full operation.

Sonotech uses TOFD inspections to keep your production at the highest level

The Sonotech team has a long-standing experience with the use of the TOFD (Time-of-flight diffraction) technology on very high temperatures. The team has executed ultrasonic weld inspections on client assets up to a temperature of 475°C (887°F).

High Precision Weld Inspection with TOFD

Welding defects can compromise the stability and integrity of a welded structure. When you need confidence in testing of welds, Time of Flight Diffraction (TOFD), a high performance non-destructive testing (NDT) technique offers you accurate detection of cracks, slag and lack of fusion.

Since the early 1990s, TOFD has been utilized in several international round robin exercises, where it was validated against the more traditional radiographic and pulse echo manual and automated weld testing methods. The results of these tests demonstrate the superior performance of TOFD. We at Sonovation have many years of experience with weld testing by means of TOFD. Our inspection team is also one of the best-resourced in the world. Our involvement in equipment development, inspection solutions and accredited TOFD training courses demonstrate our commitment in the use of this technique.

We accompany you throughout your testing project and offer you individual solutions. Our capabilities include weld testing using TOFD technique, data processing with our in-house developed software. We believe that using our TOFD inspection service will lead to major time savings during the life cycle of new build and replacement projects. It is an excellent and widely accepted pre-service and in-service inspection tool that is recognized internationally, with defined codes, standards and acceptance criteria available for its use.

Sonovation specialized in providing a complete range of advanced non-destructive testing (NDT) services. In addition to operating a competence center for advanced NDT based in the Netherlands, it maintains branches in the United Kingdom, Belgium, Germany and Saudi Arabia. Acknowledged as leaders in the field, Sonovation invests heavily in R&D and operates an accredited training school for advanced NDT as well as offering its expert services globally.

For weld inspections & wall thickness mausurements

The high temperature TOFD NII inspection capability is an excellent inspection method for weld inspections, but also wall thickness measurements with TOFD line scans, when the regular high temperature ultrasonic corrosion mapping tools are not sufficient anymore. Up to 350°C (662°F) Sonotech has standardised and validated the TOFD inspections as per the ISO pre-service standard for pressure equipment (EN-ISO 10863) in the thickness range of 6mm up to 100mm.

Benefits of Our TOFD Inspection Services at a Glance

Our TOFD inspection services offer you:

  • Higher probability of failure detection compared to conventional procedures such as radiographic testing (RT) and ultrasonic testing (UT).
  • Reduced costs, as TOFD inspections can take place on-site alongside production work during the day shift.
  • No logistical difficulty as in the case of radiographic testing.
  • Quick results, as inspection time is not as highly affected by material thickness as it is in the case of radiographic testing.
  • Material examinations and inspections are possible even to temperatures exceeding 400°C.
  • Accurate inspection data presented in an easily understood format and stored in digital form for future reference provided by our ScanPlan® software.
  • Reduced risk of company liability thanks to documented safety standards.
  • Certified inspectors in accordance with the TOFD certification program based on ISO 9712 (former EN 473).
  • The convenience of an exclusive one-stop shop solution.

Successful validation for a client at 300°C (572°F)

Successful validations and inspections have been executed at 300°C (572°F) at a client’s vital reactor with a wall thickness of 270mm. Accurate calculations about sound wave paths at these temperatures are made in advance. The TOFD high temperature inspection capability is extremely suitable to be used for monitoring purposes of known cracks.

Our TOFD Inspection Approach

We at SonoInspec are dedicated to finding the optimal non-destructive testing method that will perfectly meet your needs. Whether or not the TOFD inspection technique is suitable for you depends on many different factors. You can rely on our experience to ascertain your requirements and you can be confident of our expertise in TOFD, a technique we have utilized in testing for the past quarter of a century.

The TOFD inspection approach begins with two ultrasonic probes, which are positioned on either side of the weld, one acting as a transmitter and the other as a receiver. The longitudinal sound beam will then encounter obstacles along its path, which cause signals to be reflected and diffracted. When the probes are moved in a parallel motion along the weld, the resultant waveforms are digitized, stored on hard disk and displayed on the video-screen as a grey scale image. The image built up is in effect a through sectional view of the examined weld and can be used for accurate measurement and detection of indications. All data collected with the TOFD system is stored for future reference.

If further analysis is required on inspection data, our in-house developed custom analysis software ScanPlan®, is available. Alternatively, we can provide you with read-only data in a format compatible with the most commonly used inspection and maintenance data management systems.

TOFD Application Range

Our TOFD service can be used for:

  • Construction weld inspections.
    Intermediate inspections to examine partially filled welds at the preheat temperature.
  • In service inspection at ambient or high temperatures.
  • Examination of steam drums used in power generation.
  • Root corrosion detection in piping vessels.
  • High temperature weld inspection of up to nearly 500°C.
  • Inter granular stress corrosion cracking in welds.
  • Pre-service inspection of piping welds, duplex pipeline welds and spherical storage tanks.
  • Nozzle inspection.

Finding cracks using TOFD

TOFD is a very accurate inspection technology based on sound wave, travelling from the transmitter to the receiver and from the tips of cracks (diffract the signals). Both longitudinal and transverse sound waves can be used to achieve the highest POD. With TOFD you can accurately measure length, depth, and height of the indications in your weld. TOFD is normally not used for characterisation of the indication, like slag inclusion etc.

Transferring NDT Expertise. Helping You Grow.

In the field of non-destructive testing, it is essential that inspection and testing personnel have specific and special qualifications. We offer NDT qualification courses with trainers who have gathered a broad practical and theoretical knowledge from many years of experience. Our NDT training courses can provide formal qualifications or be tailored according to client requirements, such as training for managers or design engineers. Our NDT courses are held in various languages and are available around the globe.

More Information on Our ScanPlan® Software

With SonoInspec you get a software, that:

  • Is based upon more than twenty years’ exprerience of applying ToFD on pressure equipment.
  • Helps the professional preparation of inspections and minimises the preparation time required.
  • Implements the creation of inspection test plans.
  • Demonstrates the efficiency of the technique.
  • Has an inspection-friendly user interface.
  • Offers seven different weld configurations to choose from.
  • Offers scan parameters in accordance with international codes and standards.
  • Allows instant selection of base geometry and thickness details.
  • Optimizes the ToFD solution chosen by the operator.
  • Provides output as hard copy or digital document.
  • Records all inspection data.
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