LONG RANGE GUIDED WAVE ULTRASONIC TESTING (GWUT)

APPLICATION

Guided Wave testing (GWT) is one of latest methods in the field of non-destructive evaluation. The method employs mechanical stress waves that propagate along an elongated structure while guided by its boundaries. This allows the waves to travel a long distance with little loss in energy, guided wave technology is now commonly used as a complementary screening tool to improve corrosion detection in various pipeline, the technology may be applied to thin- and thick-walled pipe, with diameters ranging from 4” to 60”, rapidly and economically. Use reliable engineering data to assess exactly where your pipeline needs follow-up nondestructive or visual inspection.

With guided wave, low-frequency waves are sent along pipe; these waves propagate over long distances, covering 100% of the pipe wall thickness from a single inspection position. Guided wave testing is used to identify areas of concern, which are then locally scanned with conventional UT or phased array to size the indication, ensuring that the rest of the line is free of corrosion.

ULTRASONIC CORROSION MAPPING

Corrosion mapping by ultrasonics is a technique which maps material thickness using ultrasonic techniques. Variations in material thickness due to corrosion can be identified and graphically portrayed as an image. The technique is widely used in the oil and gas industries for the in-service detection and characterization of corrosion in pipes and vessels. The data is stored on a computer and may be color coded to show differences in thickness readings.

To perform corrosion mapping an automatic or semi-automatic scanner is used to scan an inspection surface, using various ultrasonic techniques including pulse echo, eddy current and phased array. Corrosion mapping is widely used in the oil, gas and nuclear industries for the inspection of pipework, pressure vessels, storage tanks and reactors. In the Aerospace sector, corrosion mapping is often referred to as ‘C-Scan’ for the inspection of ferrous and no ferrous materials. Results for corrosion mapping provide a high degree of repeatability and the advantage of position and size data for every flaw which can be compared for repeat scans of the same area to track flaw growth or corrosion rates both generally and for individual pits.