Phase 2 of the Project GRAID acceptance testing program firmly focuses on the non-destructive testing (NDT) sensors which are located on the rotating arm on the GRAID robot. The two EMAT sensors are positioned on the internal surface of the pipe and take localised wall thickness measurements before being removed and re-positioned to take another reading. There are two processes, one a sweep scan which takes readings around the full 360 degree internal pipe surface at predefined locations, such as the hour markers on a clock face. And secondly a detailed scan which allows the user to focus in on an area of interest and take many readings which can be only a few degrees apart.
The Project GRAID test rig located at the DNV GL research site at RAF Spadeadam has a man-made defect plate secured inside which the team are using to practise these scanning techniques and the results have been promising so far. The detailed scan results have shown the wall thickness change between the full amount and the reduced thickness of the defect and back again as the sensor perform its scan. This is the perfect result the team are looking for and with more scanning an image of the defect can be built up.