I am finishing up a two day inspection of two Gun Boat Rudders at the Hinckley Yard in Stuart, FL.
I used multiple forms of NDT; tap testing, thermal imaging and ultrasound (UT). For heating the rudders for the thermal imaging I used infrared lamps that are made for paint and resin curing. These lamps a great for this use, they heat evenly and slowly.
It is very important not to rely on just one form of inspection. Using multiple inspection techniques is how you can see the "big picture". I start out with thermal imaging, which I then process in software. This allows me to locate the anomalies that I will be using tap testing and UT to confirm.
Often it is possible to use an iPad with the software to due the processing on the job site. This is a way I can confirm what I see in the camera is an anomaly and then use the camera's built in later pointer to mark the anomaly.