A thermowell is a device designed to protect temperature monitoring instruments from the damaging effects of corrosive media, high pressure and velocity in industrial applications. Without the protection of a thermowell, temperature instruments can become inoperable, putting your whole operation at risk. Ashcroft is a global leader in temperature measurement instrumentation. We created this article as part of our Understanding the Basics series to provide a foundation of information about thermowells. If you are an industry novice or just want a refresher on how thermowells work, this is a great place to start. In this article, you will discover where thermowells are used, learn about the different types of thermowells, see how they connect to the process piping and more. When you are done reading, you will also find additional resources that may interest you.

Thermowells are used to protect your temperature measurement instruments from the elements, which means they are often exposed to extreme environments and temperatures. Protecting the thermowell can help keep your temperature instruments safe and your application running. But how do you protect an instrument that’s designed to protect other instruments?

Thermowells are essential to protecting your thermometer or temperature sensor in your high-pressure or high-temperature applications. They can protect your investment and keep your measurements accurate, no matter how extreme the environment. One of the top questions we receive here at Ashcroft from those in the temperature measurement industry is how to properly fit a thermowell. What measurements are needed? What is a u-dimension and how does it factor in? Many factors are at play, and it can be easy to get the wrong size if you aren’t paying attention.