Home > Case Studies > Case Three Determining safe life of refractory lined vessels of liquid steel The Problem Modern secondary steelmaking techniques involve the containment of liquid steel in large refractory-lined ladles (holding up to 150 tons of steel) for considerable periods of time, sometimes measured in hours rather than the minutes of older methods. This increased time provides the opportunity for liquid steel to penetrate the refractory and heat up the outer steel shell of the ladle. Once this occurs, failure of the ladle can be rapid and catastrophic. It is very desirable to have early warning of any potential hot-spots on the ladle shell, as these may indicate a weakness or worn area of the lining. The conventional method of monitoring such vessels is by manual survey using a thermal imaging system. This is excellent, but very expensive in hardware and manpower. The Solution A specially modified camera, sensitive to infra-red radiation is attached to a remote optical pyrometer, and both instruments view coaxially through the same optics. The complete assembly is enclosed in a heavy-duty housing (which may be cooled if necessary) and mounted on a remotely-controlled pan/tilt mount so that it may be directed to any point of interest. The operator sees what appears to be a conventional television picture of the ladle (or other vessel), but any areas that are hotter than normal (>400 degrees) appear to be incandescent. A small target window in the picture indicates the sensing area of the pyrometer, and the operator simply has to move the controls for the pan/tilt unit to position this window over the area of interest. A digital readout then shows him the actual temperature of the vessel skin at that point, allowing a safe go/no-go decision to be made. This system is very significantly cheaper than thermal imaging systems, and provides a much higher quality picture.