What is the purpose of a thermowell?

A thermowell is a protective tube that allows temperature sensors (RTDs, thermocouples) to be inserted into a process while protecting them from pressure, flow, and corrosive media. Thermowells enable sensor replacement without process shutdown, protect sensors from mechanical damage and velocity effects, and isolate the sensor from hazardous environments. They must be designed to withstand process pressure and prevent wake frequency vibration-induced failures.