In industrial process, to shield the temperature sensors thermowell is used. Thermowell is a cylinder shaped fitting. At one end a tube is closed and mounted in process steam is thermowell. Thermocouple, thermometers are such temperature sensor is inserted in the tube which has an open end. This is generally outside the process piping in the open air. The procedure of process fluid transfers heat to thermowell wall is thermodynamically which transfers heat to sensor. By the addition of well, the response of sensor to process temperature alterations is slowed as, with a sensor-well assembly there is more mass than with a probe immersed in the process directly.
The sensor is easily replaceable without draining the piping, if it fails. By adding the thermowell, the sensor accuracy is reduced as walls of the thermowell conduct heat out of the process and the mass must be heated to process the temperature. To ensure the integrity, they are intended to manufacture for high pressure applications are generally machined from bar stock. For low pressure applications, the thermowell manufactured from tubing with one end welded closed.