Infrared Inspection Techniques

Abstract

Infrared scanning equipment has been used at Amoco's Texas City refinery since 1971 as an inspection tool. A camera scans the field of view and focuses the infrared radiation on a detector which converts the infrared signal to an electrical signal. By means of a TV monitor tube, a thermal picture is formed where lighter parts represent areas with higher temperatures. Absolute temperature levels of objects can be measured with this technique from -300C to +20000C. A conventional camera is attached to the display to take a picture of the thermogram when a permanent record is desired.

The primary uses of infrared scanning in refinery work is for determining internal conditions of process equipment, and measuring heat losses from equipment for energy conservation. There are many examples of the use of this technique but a prime one is the determination of the condition of internal refractory linings in pressure vessels that are in service.

The infrared equipment is truck mounted. Remote controls enable an operator to raise or lower the camera vertically or swing it horizontally, thereby allowing much of the work to be done from the truck. The camera is removable and can be placed at any distance from the object to be studied. Measurements can be made from a distance of several hundred yards with no significant absorption by the atmosphere.