Eddy current non-destructive technique adopted widely
Case Study
Example of contaminated weld inspection using the Eddy current technique
A novel NDT technique for inspecting contaminated stainless steel welds in LNG plants has been successfully developed at TWI.
A fast and reliable solution was implemented using the low frequency eddy current technique developed by TWI's Alan Day.
The technique is able to detect defective welds with
wall thicknesses up to eight millimetres. To calibrate the system
accurately, stainless welds were manufactured at TWI with known amounts
of ferritic consumable in the weld root.
An inspection procedure was then developed and TWI personnel were trained to carry out the inspection.
The system was applied to stainless steel pipelines
in a production plant in the Middle East. An inspection rate of
approximately 100 welds per day was achieved. In addition, the
performance of the system was found not to be affected by temperature
variation of these pipelines.
This is one example of a number of innovative solutions developed by the
NDT Technology Group using Eddy current techniques. Further examples
are:
Example of Eddy current signal taken from Phasec 2200 system which indicates defective weld
- EC inspection of bridge stays.
- EC inspection of vintage aircraft propeller hubs.
- Inspection of Zircalloy welded tubes.
- Detection and sizing of surface flaws in brake drums.
- Boiler tube inspection.
- Weld penetration depth measurement in stainless steel shafts.
- Measurement of contamination levels in welds in titanium and zirconium.
- Ultrasonic phased array inspection of storage tank annular fillet welds.
