How to calculate the minimum pipe wall thickness in this scenario

[Ageraluon]

Hey guys,

Hope you can help me with the following practical problem I am facing right now. I plan to build a pipe system in which ethanol (vapor/liquid) is being conducted at pressures from 1 atm to 10^(-2) atm. What would the minimum pipe wall thickness be if the pipe material was

a) copper
b) Aluminum

Hope for your help!

 

[xxChrisxx]

Hoop stress.
http://en.wikipedia.org/wiki/Cylinder_stresses

In reality with a maximum differential of 1 bar (ish), you can use anything you like so long as it's compatible with ethanol.

 

[Q_Goest]

For pipe in vacuum, and assuming this is an industrial application, you'll need to follow the applicable piping code in your country. For the US, that code would be ASME B31.3, paragraph 304.1.3 which essentially directs you to the BPV code, Section VIII, Div 1, para. UG-28 through UG-30.

 

[Ageraluon]

Thank you guys, will try my best! Where can you obtain the respective ASME code from?

 

[Q_Goest]

What country are you in and is this for an industrial application?

 

[Ageraluon]

I studied in the US but am working on a short project in India right now. The project is semi-industrial, its a prototype with the possibility to be manufactured in larger scales later.

 

[Q_Goest]

I'm not familiar with the codes in India but I would assume they exist. I'd suggest checking with other engineers in your company to see what codes govern your systems. Am I correct in assuming your low pressure is vacuum? If so, what diameter pipe are you looking to use? If this is small diameter (ie: less than 3") then any standard sized pipe will work. If this is strictly positive pressure, there's even less of a problem. Regardless, you should find out what codes govern your installations and use them.