Principle, Equipment and Applications of Line-Scanning Infrared Thermographic NDT

The Line Scan Thermography (LST) technique for thermal nondestructive testing (TNDT) uses continuous heating from an incandescent (quartz) linear tube heater. This provides a continuous linear inspection with a lower noise level than the classical single area Xenon flash TNDT technique. The basic theory of the LST technique is described, along with a description of a special, self-propelled LST device. It is shown that TNDT processes using a moving heat source can be evaluated by solving simpler, static TNDT problems using flash heating. An example of the experimental detection of hidden corrosion in steel is presented. The LST method is recommended for the continuous inspection of large objects, especially flat, cylindrical and/or conical shapes.