PIPE SIZING (DIAMETER)

[Berenger]

I have just read ASME B31.3 for the second time and understand all other aspects of the standard, except calculating pipe size.

I can't find any section in the standard (B31.3) that deals with pipeline OD (or ID) calculations. The closest I can see is to determine the pipe thickness and work back from that to the pipe diameter.

Is this right? I can determine thickness, yield, coefficient, allowable stress...everything EXCEPT the most important - pipe size/diameter.

I appreciate any help. I will appreciate if someone can just tell me what section to look at more closely or what section has the sizing equation.

Thanks.

 

[bimr]

Sizing of pipe diameters is based on the fluid properties and fluid flow requirements, not on the ASME Code. The Code is used to calculate the pipe thickness, etc.

 

[Montemayor]

You have your calculation methodology all mixed up.

Process Engineers determine the size of pipe required for their process design based on the allowable pressure drop and the recommended fluid velocity.

The pipe size specification is subsequently usually turned over to a mechanical engineer who determines or selects the pipe wall thickness (or schedule #) based on the projects piping specifications and the applicable pipe code (such as ASME B31.3)

You are trying to apply ASME B31.3 to the determination of the pipe size - that is backwards, like tying the cart before the horse.

 

[Berenger]

Thanks, guys...now it all makes sense.

 

[racookpe1978]

Well, technically speaking, he is trying to figure out the size the horse based on a formula for the diameter of the cart wheel. Without knowing the weight and volume of the load he will pull, the the size and speed of the cart he wants to pull, or the type of road over which he will pull the cart. 8<)