Rotary probes for steel tube inspection

The wide use of steel alloys for tubes requires careful inspection during manufacture and service. Tubes for different applications may be made of specific steel alloys. The Sandvik SAF 2507 tubes are made from a super-duplex (austenitic-ferritic) stainless steel. Sandvik Chomutov tubes are used for oil and gas exploration and production as high pressure hydraulic fluid tubes in umbilicals. To ensure high quality and cost reduction during the manufacture, it is important to find imperfections on internal surface of input material (hot finished tubes) prior releasing for final processing (cold pilgering). The imperfections to be searched are especially dents, impressions, cracks, tears and non-metallic inclusions (residuals of glass after hot process). Eddy current method is an essential part of non-destructive testing and one of the main methods used for tube inspection.

Umbilical tubes                                      The super -duplex stainless tube specimens

 

To ensure the detection of these imperfections, it was necessary to develop a special eddy current probe which is capable of detecting shallow discontinuities in a magnetic material. The probe operates in the frequency range from 250 kHz to 1 MHz. 

 

Eddy current responses for artificial flaws:

   

   

   

 

This probe was presented on 11th European Conference on Non-Destructive Testing 2014 in Prague, Czech Republic http://www.ecndt2014.com

http://www.ndt.net/events/ECNDT2014/app/content/Paper/293_Bohacova_Rev2.pdf