Corrosion Mapping by ultrasonics is a non-intrusive 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 stored on a computer and may be color coded to show differences in thickness readings. Corrosion may be mapped using Zero degree ultrasonic probes, an Eddy Current array and/or Time of Flight Detection methods.