In cladded thermowells, a coating or sheath is added around the thermowell. This is done when, due to process conditions such as high temperatures or an aggressive medium, a corrosion-resistant material is required.
These corrosion-resistant materials are often very costly. With a cladded thermowell, only the outer surface exposed to the process is covered with the corrosion-resistant material, while the thermowell itself is made from a more affordable material.