# Thread: Shell thickness for an Indirect Heater

1. Junior Member

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Dec 2008
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## Shell thickness for an Indirect Heater

Goodmorning,
i have to design an indirect fired heater to heat a stream of crude oil.

I have sized all the process, what remains is to calculate the thickness of the shell. The API 12K only tell me that i have to design the shell based on Asme VIII div. 1, but it gives me no other inputs.

The shell has these dimensions:
-lenght: 15000 mm
-diameter: 3600 mm
-full of liquid (water/glycol)
-design pressure: atmospheric
-material: carbon steel

How can i calculate the vessel thickness in order to be sure that the vessel will resist to the weight of the water? Is there any formula?

I've tried to use the formula given by ASME regarding pressure vessels, but it gives me a ridocolous thickness (1mm). I think i cannot use this formula to calculate the thickness of an atmospheric thanks

p.s. My boss suggested me to consider a thickness of 12 mm, but i would like to understant WHY he gave me that number...

Thank you
Matteo

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3. Senior Member

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Hi design with ASME code and 15 psi of design pressure and then select the next up thikness comertial for example if ASME code gives 0,145 in select 0,1875 in not forget the corrosion minum if you don't have data 1/16 in

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5. Junior Member

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Dear Mattegam,

m.shahverdi@gmail.com

Thanks

6. dso
Active Member

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Originally Posted by mahdishahverdi
Dear Mattegam,

m.shahverdi@gmail.com

Thanks

Indirect Heaters Design Manual, Sivalls, Inc., Odessa, Texas.

if only you can find it..

7. hbr
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## Re: Shell thickness for an Indirect Heater

Dear Sir
It would be greatfull if you could share this manual for us. I need it ergently for my work. In fact I dont khow how I shold size fire tube to sure the required heat released to heating medium is sufficent.
Best regard

8. Junior Member

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## Re: Shell thickness for an Indirect Heater

API 12K latest addition will give guidelines to determine the diameter of the firetube. The length has to do with the flame length as you want to have several feet past this distance at high fire. This distance determines the main leg of the firetube and if it is a return type then two times that distance will give you the total length for surface. You may need more surface for forced draft burners that can fire into smaller diameter firetubes than what is used for natural draft. The length of the first leg will also determine the overall length of the water bath shell. Since the shell is open to atmosphere then the only pressure you have is the height of the liquid. The main concern there is not so much the shell itself but the end plates. The thickness of them is more guided by the height of the liquid and the fact you have force on a flat plate. A good book to have is the 'formulas for stress and strain' by Roark & Young.
I hope this helps.

9. Junior Member

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## Re: Shell thickness for an Indirect Heater

hi, can you send API 12k code in pdf format