When it comes to manufacturing and finishing metal, heat plays a significant role. However, a specific degree of heat rather than intense amounts of heat is a critical factor. This is because the actual temperatures in the individual production processes are of vital importance to the end product. If the specified temperature is not reached and maintained, this can be detrimental to the quality of the product. For this reason temperature measurement is the backbone of quality assurance.
When taking temperature measurements ranging from 800°C to 1700 °C there are particularly high demands on the measuring technology used. Many materials can only withstand the heat and other process conditions for a limited period. While some processes involve corrosive gases, other processes can be abrasive. This is exacerbated by turbulence and other extreme conditions, which make things more difficult for the component parts of a thermometer, particularly the thermowell. A combination of corrosion and abrasion is often the root cause of thermowell failure.
At critical measuring points, measurements are either not taken continuously or the thermocouples must be replaced quite frequently. These measuring points increase the workload of the maintenance departments, drive up costs and are often difficult to access. In recent years, materials research has provided us with many new materials, ranging from new metal alloys to robust ceramic substances. Endress+Hauser has examined and tested these new materials, and found it possible to use some to produce thermowells that withstand extreme process conditions far longer than previously experienced. The new thermowell materials have been tested in applications where lifespan in the past has usually ranged from one day to just a few weeks, such as in the metal industry, cement production or waste-to-energy plants.
Frequently, conditions are not only harsh but also change unpredictably. Thanks to the new thermowell materials it has been possible to extend the operating life of the high temperature sensor several times over in these very processes. The thermowells both provide mechanical protection for the thermocouple, and prevent the penetration of gases that cause temperature drifts and failure due to corrosion.
A thermocouple designed with the optimum thermowell material makes the process more reliable, accurate, manageable and stable over the long period. This drives down maintenance costs and improves quality, process safety, and safety at work.
Endress+Hauser has incorporated its research and testing results into the Omnigrad S TAF high-temperature sensor line. Given the extensive possibilities of combining the TAF11, TAF12S, TAF12D, TAF 12T and TAF16 devices, the ideal thermocouple can be designed for every application. With the new thermowell materials thermocouples can be used in an even wider range of applications.