Title :
Time of
Flight Diffraction (TOFD) as a Substitute to Radiography in Inspection of
Welded Joint: An Advanced Ultrasonic Test
Author : Ayman Nadim Abd El-Hamid Sherif
Collection : M.Eng. Production
Abstract:
Time
of Flight Diffraction (TOFD) is a new ultrasonic NDT method which has been well
established in many industrial countries, however in Egypt it is still knocking
on the door.
In this work a comprehensive review of TOFD covering many of its aspects, e.g.
accuracy, coverage, resolution, reliability, and last not least the speed where
the real value of TOFD is saving time. A review of the fundamental of
ultrasonic inspection on which TOFD is based on had been carried out. A review
of the most widely spread NDT method for inspection in Egypt, RT, has been
introduced.
TOFD technique is considered as one of the fastest methods of Non-destructive
testing (NDT), the weld can be inspected with one single scan along its length.
An experimental work has been carried out on carbon steel plate 22 mm thick,
butt welded with a single V- groove joint was prepared by grinding, and this
specimen was welded using a Shield Metal Arc Welding (SMA W) with E 7018-1
electrodes. An artificial defect was introduced into the specimen by drilling a
whole 3mm diameter and 8mm deep in the weld metal. The specimen was inspected
by both Radiographic Test (RT) and Time of Flight Diffraction (TOFD).
Comparison between the results of inspection by TOFD and RT, show that RT
reveals a projection of the defects not showing its length while TOFD show the
defect in two dimensions. The results show the feasibility of using TOFD as an
alternative to replace the traditional radiographic test (RT) method in
inspection
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