An evaluation of the efficiency of laser scanning technology in the quantitative analysis of corrosion

Abstract

It is estimated that corrosion causes around R260 Billion of damage to infrastructure and equipment in the South African industry annually. Corrosion evaluation and protection in the marine environment is well established. In the mining industry the field of corrosion evaluation is not as well established as it could be. The evaluation and measurement of corrosion rates and physical deterioration of structures through electrochemical measurement, visual inspection and non-destructive test method measuring techniques are well established. The use of sonar (ultrasonic) and laser scanning has been investigated. Laser scanning technology has improved exponentially over the past years and terrestrial and hand-held units are now smaller, more manageable and affordable to the surveyor. Conventional laser scanners are able to measure to an accuracy of millimeters and generate a point cloud of 1million points per second in some cases. Latest developments in laser scanning include multi-spectral analysis and Red-Green-Blue (RGB) intensity values for each point. Point clouds of data can now be imported into a CAD package and compared to design specifications. In the case where "as-built" specifications differ for the initial design, laser scanning allows the engineer the opportunity to compare and quantify in minute detail the differences between the final structure and the original design. This paper discusses a test during which a corroded and "fouled" pipe was scanned under laboratory conditions using two types of conventional scanners. A field test was performed on two marine vessels to determine the feasibility of laser scanning to complement standard corrosion measuring methods. The application of laser scanning in this field may provide a valuable tool in the detection, measurement and analysis of corrosion in structures.