Corrosion inspection on pipelines with shearography

Pipelines can be inspected quickly and reliably on inner corrosion by means of laser shearography. During pressure change in the pipe shearography measures all strain concentrations on the surface of the pipe. As corrosion leads to local wall thinnings inside the pipes these areas will expand more than non corroded areas and thus be indicated by shearography from the outside of the pipe. In this paper important features and conditions are described for application of this technique for inspection in power plants. It is reported about experience on practical inspection tasks. Latest developments enable numerical data processing and graphical and coloured data presentation for easier defect recognition. (orig.)