Abstract

The RFEC method is used for the inside control of pipes with diameters exceeding 100 mm. Most of the published works refer to the response of the RFEC equipment to standard defects (longitudinal or transversal channels simulating cracks, or flat bottom holes simulating corrosion). The reception is ensured by a pick-up coil with ferromagnetic core which sweeps the inside pipe surface. With the equipment advancing inside pipe for a speed correlation ensured, the whole inside surface is being inspected.

For the in-service inspection of the buried or submersed pipes, the installation is endowed with more pick-up coils in fixed positions, completely covering by their sensitive area the pipe inside surface. We have chosen this constructive version considering the concrete working conditions: silt and calcium salts deposits on the walls, high humidity.

The installation consists of two parts: the mobile part moving inside the pipe consisting of the emission and reception coils separated by a distance about twice the conduit diameter, the power amplifier for the emission part, the compensation systems, the band pass filter, the synchronous detector and the analogue digital converter. The steady part include the proper acquisition system, the serial interface for the coupling to a lap-top for data registration, storage and processing, the system for equipment position determination and the power supplies.

The measurements are performed every 5 cm., this representing the transducer sensitive zone. The equipment is able to detect the corroded areas of more than 25% wall thickness, as well as the pores with diameters exceeding 1 mm.

Keywords: Eddy Current Testing

Source: Conference Proceedings of the 4th International Conference of the Slovenian Society for Nondestructive Testing, 24 - 25 April 1997, Ljubljana, Slovenia.
Pages:379

Publisher:
Slovenian Society for Nondestructive Testing, Faculty of Mechanical Engineering, Askerceva 6, SLO 1000 Ljubljana, Slovenia. Tel +386 61 177 12 03, Fax +386 61 218 567, Email: janez.grum@fs.uni-lj.si.