Mark Badrick: About the Author
Senior Reliability Engineer, Bahrain Petroleum Company

The title question is often asked and more often than not, impossible to answer. This paper follows on from a previous discussion (Inspectioneering Journal Volume 4 Issue 1 Jan/Feb 1998) relating to the difficulties arising whilst attempting to carry out temperature surveys of furnace tubes using a thermal imager. The issues discussed then i.e. calculation of emissivity and ambient temperatures, reflected heat etc, are still current concerns, but since the writing of that article, an additional equally important challenge has become apparent - "how do we measure the temperature of an externally scaled or fouled tube"? Where the external scale or some other external deposit, such as refractory dust etc. may mask the true tube temperature.

The use of Infrared Thermal Imagers, particularly for temperature measurement within an operating furnace environment, is reliant on the accurate evaluation of specific parameters, which the pyrometer requires in order to produce true temperature measurements.