How to Specify a Thermowell

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Thermowells are available for light duty applications, high pressures, high temperatures and high velocity applications. They are used to meet many general service industry needs and are selected on the basis of pressure, temperature, flow, vibration and corrosion parameters. The basic thermowell types include: threaded, socket weld, weld in, flanged, sanitary and van stone. The threaded type is generally the least costly and most versatile. The schematic of a typical thermowell and all parts required to specify a thermowell for proper selection is shown below:

Thermowells

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The process environment where temperature monitoring is required is often not only hot, but also pressurized and possibly chemically corrosive or radioactive. To facilitate removal of the temperature sensors (RTD and Thermocouple), for examination or replacement and to provide mechanical protection, the sensors are usually mounted inside thermal wells widely referred to as a thermowell in the industrial environment

What is a Thermowell?

A thermowell is basically a hollow metal tube with one end sealed. It is usually mounted permanently in a vessel or pipe work. The sensor is inserted into it and makes contact with the sealed end. 

A simple diagram showing a thermowell in use with a temperature gauge is shown below: