# How to select correct thermowell for temperature measurement application?

**URL:** <https://forumautomation.com/t/how-to-select-correct-thermowell-for-temperature-measurement-application/952>\
**Category:** Temperature Measurement\
**Created:** [April 2, 2016, 3:54am UTC](https://forumautomation.com/t/how-to-select-correct-thermowell-for-temperature-measurement-application/952 "2016-04-02T03:54:23Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![denizen](https://forumautomation.com/letter_avatar_proxy/v4/letter/d/848f3c/32.png) [@denizen](https://forumautomation.com/u/denizen)\
**Post date:** [April 2, 2016, 3:54am UTC](https://forumautomation.com/t/how-to-select-correct-thermowell-for-temperature-measurement-application/952/1 "2016-04-02T03:54:23Z")

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**Selection Of Thermowell**

You need to find out answers for 3 questions for selecting correct thermowell .

**1.What type of connection you are making to the process ?**

Most common type of thermowell connections are

a)Threaded Applications of Threaded Thermowell- It is used where frequent removal is not required. It is commonly used in small pipes or vessels and Non-Corrosive media.

b)Flanged It is used applications where frequent removal is required. Common applications - Large Pipes,High Pressure,High Corrosion

c)Socket Welded These thermowells are welded directly to pipe or tank and it provide a high quality connection. Since they are welded it cannot be removed easily.It should be used only where access is not required and corrosion is not an issue. Common application - High Temperature,High Pressure,Non-corrosive media

d)Sanitary These thermowell has a smooth surface which is easy for cleaning.This prevents contamination of the process. Common application - Diary,Food processing,Pharmaceuticals

 ![Thermowell Connection type -Threaded-Flanged-Welded-Sanitary](https://cdn.forumautomation.com/original/1X/4d5cce5f55938168fe328f1d25a3b7cabb0118ea.jpg)

**2.What is the best material of construction for the application?**

Consider the following factors for selecting the correct material.

a) Temperature Limits of the material

![Temperature Limits of Thermowell Material](https://cdn.forumautomation.com/original/1X/9d90f2d25a5f7f39b6b41f61700ff0d3cc6ed3d8.jpg)

b)Chemical Compatibility with the media

![Thermowell Materials Used](https://cdn.forumautomation.com/original/1X/0569ba3dbbaaa970081bb552eac8a7a04513d147.jpg)

c)Compatibility with the process piping material

**3.What is the best stem profile for the application?**

a) Tapered Tapered Stem profile have good response time and good strength. Consideration - High Drag Force

b) Straight Advantages - High Strength Disadvantages - Slow response time,High Drag Force

c) Stepped Advantages - Low Drag Force,Fast Response Time, Disadvantages - Lower Strength,

![Thermowell Stem Profile Types](https://cdn.forumautomation.com/original/1X/d8b80ddb253d3ddfef16494471d6a459f682add9.jpg)

Additional Consideration for thermowell Failures 1.High Drag Force 2.Excessive Static Pressure 3.High Temperature 4.Corrosion 5.Fluid-induced vibration