Thermowells are one of the major temperature measurement accessories that are usually made of solid drilled bar stock and are designed to protect temperature sensors from wind, high pressure and harsh environments.

A thermowell acts as a barrier between the sensor element of the measuring device and its process medium. It safeguards the temperature sensors such as thermocouples, thermistors and bimetal thermometers against corrosive process media, high-speed and pressurised images.

It can also remove the sensing factor from the application while a closed system is retained. These also increase the sensor durability, allow sensor replacement without dripping out the device and reduce the likelihood of contamination.

Thermowells are used for high-pressure applications which are typically machined from bar stock to retain integrity. A tube with one end welded can be built from smaller thermowell used in low-pressure environments.

Thermowells are concealed in pipes and occasionally seen. They are permanently mounted in the tubes, tanks or in sumps in order to insert temperature measuring probes into the tube to measure the temperature of the contents. For installations,  seal, welding and brazing are necessary. The pipe thread provides mechanical strength, and the seal is formed by the weld or braze.

Thermowells usually comes in various shapes. The installation of temperature sensors in or directly into thermowell includes some form of brass or stainless steel fitting.

A wide variety of thread or flange fittings is available, depending on the installation specifications. Various unions, bayonet cap and the flange, are included in the fitting. An adjustable compression fitting is directly applied to the test to ensure proper shearing of the samples into the thermowells to achieve the required insert length during the process.