What is Time of Flight Diffraction (TOFD)?
TOFD – Time-of-Flight Diffraction – is an ultrasonic technique which measures the time of flight of a pulse as it travels from a transmitting probe to a receiving probe. Divergent beams are used and it is necessary to scan the TOFD probe pair over the flaw for the technique to function correctly.
Method of Inspection | Applications
TOFD is used for accurate detection, sizing, and positioning of weld defects in pressure vessels, pipelines, and structural components. What distinguishes the technique from a standard pitch-catch configuration is the D which stands for diffraction. The technique relies on the detection of the diffracted sound wave which is generated from both the top and bottom edges of a planar defect.
The time of arrival of the diffracted signals from the flaw tips is measured with respect to the probe firing time. Time measurement can be done to great accuracy. The combination of this accuracy and the fact that the scattering source is the flaw tip forms the basis of a highly accurate sizing technique.
Materials Suitable
- Carbon and low‑alloy steels
- Stainless steels
Inspection Capabilities
- High‑resolution TOFD scanning
- Accurate defect sizing and depth measurement
- Digital data capture and analysis
Process Overview
- Inspection planning and calibration
- Transducer setup
- Ultrasonic data acquisition
- Signal analysis and interpretation
- Reporting and evaluation
Industries We Serve
Oil & Gas, Petrochemical, Power Generation, Fabrication
Key Benefits
- Accurate defect sizing
- High sensitivity to cracks
- Reduced interpretation uncertainty
- Permanent digital record
Reporting & Deliverables
- TOFD scan data
- Defect location and sizing reports
- Code compliance evaluation
An online reporting system is available to our customers, allowing 24/7 access to reports.
Why Choose Us?
- Certified TOFD inspectors
- Advanced ultrasonic equipment
- Reliable and traceable inspection results