Identification and sizing of defects in metallic pipes by remote field eddy current inspection

The remote field eddy current (RFEC) technique is a through-wall non-destructive method of evaluating pipelines for defects which can be used in metallic pipes, both magnetic and non-magnetic. Although pipe replacement policies in the UK have been successful, corroded pipe can be missed and sometimes pipe with significant remaining life has been replaced unnecessarily. When effective inspection devices become available essential pipeline replacement and maintenance programmes can be prioritised. The cost of these programmes will then be significantly reduced. This paper outlines the requirements of a system suitable for inspecting 100 mm diameter metallic pipe and gives a brief description of some of the reported applications of the technique. The development route being pursued by the current author and the results of initial laboratory tests and held trials undertaken with the prototype vehicle are described. Defects have been successfully detected in schedule 80 steel and ductile iron pipe. Finally, the proposed future development of the technology and how the miniaturised vehicle will open up new market opportunities are mentioned. The RFEC inspection system is currently under development at the company and it is expected that preliminary evaluation trials, in a number of defective pipelines, will take place in 1999. (C) 1999 BG Technology. Published by Elsevier Science Ltd. All rights reserved.