#  > Petroleum Industry Zone >  > Instrumentation & Control >  >  >  Thermowell Insertion length (U)

## Renz Ramirez Olvido

Good day to everyone. Do we have a standard regarding the thermowell insertion length.
if so, please give me a link. All i see here are the thermowell calculation for the wake frequency. 
Would you recommend a thermowell in a 3 in pipe carbon steel sch 80? with natural gas flowing and 80psi of pressure, would flanged connected well be ok?


Thanks.See More: Thermowell Insertion length (U)

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## amshah

Dear Freind,

If i am correct there is no std available for insertion length, but the design thumb  rules are available which states that your thermowell shall be located in pipe center( where fluied valocity is max and actual temp will be measured, on near to wall flow velocity will be less and temp loss due to conduction will be there), hence your thermowell incertion shall be 40 to 60 % of your pipe ID.


RF Flanged thermowell can be used upto rating of 300# without any problem and 600# in non hazardous fluids like air, n2 etc. in your case you have 5 kg or 60 psi pressure and atm temp hence rating of 150# flange which is easily used. If U R using above 600 # then welded , ring joint flange  needs to be used.

hope it meets your requirement.

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## Renz Ramirez Olvido

Amsha,

thanks for the information. i am still confused with the immersion length. I read that it is recommended to install the TW iin an elbow if the pipe is 3 inches. The manufacturer says that 10 to 15 times the diameter of th TW will be sufficient for immersion.
With 13.5 tip diameter, 6inches immerison would suffice. Am i right?
Thanks.

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## amshah

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> Amsha,
> 
> thanks for the information. i am still confused with the immersion length. I read that it is recommended to install the TW iin an elbow if the pipe is 3 inches. The manufacturer says that 10 to 15 times the diameter of th TW will be sufficient for immersion.
> With 13.5 tip diameter, 6inches immerison would suffice. Am i right?
> Thanks.



I think this is not 100% correct, this will make same length of TW for fixed tip size.

i am sharing some of my project drawings  hope would like to you. !!!!!!!!!!!!!!!!!!!!!

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## Renz Ramirez Olvido

Where's your drawing?
thanks

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## hacklers

CMIIW,

usually i confirm the insertion lenght with "Wake Frequency (fw) Calculation".

if the _fw/fn_ less than 0.8. so your insertion length is accetable

thank you

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## amshah

"Wake Frequency (fw) Calculation" is used to check mechanical strength of thermo well, insertion length can not be calculated based on thermowell wake frequency calculation. am i correct ****lers ?

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## Renz Ramirez Olvido

i donwloaded the wake frequency calculator. thanks everyone

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## Shabbir2009

You can refer to API RP 554. You may need to expand 3" to 4" pipe for having a flanged thermowell. Else you may install it on a 3" elbow. The insertion of the well should be in the centre third of the pipe.Hope this clarifies.

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