Subscribe to our newsletter to receive the latest news and events from TWI:

Subscribe >
Skip to content

Industry benefits from new technique

Connect, no. 156, November/December 2008

Eddy current inspection of vintage aircraft propeller hubs
Eddy current inspection of vintage aircraft propeller hubs

A novel, low frequency eddy current (EC) NDT technique for inspecting contaminated stainless steel welds in LNG plants has recently been developed at TWI.

The EC technique is capable of detecting defective welds with wall thicknesses up to 8mm. In order to accurately calibrate the system, stainless welds were manufactured at TWI with known amounts of ferritic consumable in the weldroot. A procedure was then developed and TWI personnel trained to carry out the inspection.

The system was applied to stainless steel pipelines in a production plant in the Middle East during which 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:

  • 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

For more information, please contact us.

An example of contaminated weld inspection using Eddy current technique
An example of contaminated weld inspection using Eddy current technique
An Eddy current signal taken from Phasec 2200 system which indicates defective weld
An Eddy current signal taken from Phasec 2200 system which indicates defective weld

For more information please email:


contactus@twi.co.uk