Thermo-Well for Temperature Measurement

Thermo-well is a protective sheath that surrounds a temperature sensor such as thermocouple, resistance temperature detector (RTD), or thermistor. It is used to measure the temperature of hot fluids, gases, or steam in industrial applications. The thermo-well protects the sensor from the corrosive, erosive, or high-temperature environment and allows for easy removal or replacement of the sensor without interrupting the process.

Thermo-well Material Selection

The selection of thermo-well material is critical to ensure accurate temperature measurement, long-term reliability, and safety in the process. The thermo-well material should have the following properties:

1. High-temperature resistance: The material should be able to withstand the maximum temperature of the process without degrading or melting.

2. Corrosion resistance: The material should be resistant to the corrosive effects of the process fluid, which may contain acids, alkalis, salts, or other chemicals.

3. Mechanical strength: The material should be strong enough to withstand the pressure, flow, and vibration of the process fluid.

4. Thermal conductivity: The material should have good thermal conductivity to allow for fast and accurate temperature sensing.

5. Cost-effectiveness: The material should be affordable and readily available.

Steel Thermo-Well

Steel is the most widely used material for thermo-wells due to its excellent temperature resistance, corrosion resistance, and mechanical strength. Stainless steel, such as 316L or 304, is commonly used for corrosive applications, while carbon steel, such as A105 or A106, is used for non-corrosive applications. Steel thermo-wells can withstand temperatures up to 1000°C and pressures up to 100 bar. They are also relatively low-cost and easy to manufacture.

Brass, Copper, and Aluminium Thermo-Well

Brass, copper, and aluminium are not suitable for thermo-wells due to their low-temperature resistance and poor mechanical strength. Brass has a maximum temperature limit of 250°C and can corrode in acidic or alkaline environments. Copper has a maximum temperature limit of 200°C and can deform under pressure. Aluminium has a maximum temperature limit of 150°C and can melt at high temperatures. These materials are only used for low-temperature applications or as decorative covers for thermo-wells.

Conclusion

In summary, the thermo-well material selection is critical for accurate temperature measurement and long-term reliability in industrial applications. Steel is the most suitable material for thermo-wells due to its high-temperature resistance, corrosion resistance, and mechanical strength. Other materials such as brass, copper, and aluminium are not recommended for high-temperature applications.

At high temperatures thermal conductivity of steel is higher than others.