Tube formulas

[Dropout]

Hi All.

I'm looking for two formulas:

1. The number of tubes that can fit in a given circular arrangement similar to a boiler.

2. The length of tubing needed to form a coil.

Thanks in advance.

 

[dicksewerrat]

One tube in the circular arrangement. Outside diameter of pipe equals diameter of arrangement.
Make a coil, unroll it and measure.
Questions entirely too vague.

Richard A. Cornelius, P.E.

http://WWW.amlinereast.com

 

[rmw]

If I understand your question, it seems that you are asking how many tubes will fit into a circular boiler tubesheet. If so, here is a link.

http://www.sugartech.co.za/software/tubeplate/index.php

rmw

 

[katmar]

1. The SugarTech reference is good, but if you want to build it into a spreadsheet or calculation it is easy to get a rough estimate. For holes on a triangular pitch the ratio of the total area of the holes to the tube sheet area is 0.9069 x (D/P)^2 where D is the hole diameter and P is the center to center pitch of the holes, both in the same units.

From this ratio you can work from the number of tubes to the tubesheet size, or the other way around.

What it does not take into account is any partition plates to create multipass units, and also the unperforated area around the edge of the tubesheet.

2. When you bend a tube to make a coil the outer edge will stretch, and the inner edge will compress. So the total length of the coil measured on the outer edge will be longer than the tube that was used to make it, but the total length on the inner edge will be less than the original tube. The choice of which length to use depends on what you want to use the calculation for. If I was estimating how much tube to purchase I would use the outer edge to ensure that I had sufficient pipe. If I was estimating the length to get the area for heat transfer I would use the inner edge to ensure I was not overstating the area.

 

[orch]

Agree with Katmar and to work out the length of which ever line you decide to use, (personally I'd take the centre line then add on a margin for rolling as it will need to be overlength anyway)Imagine rolling 1 turn along a flat surface. The diameter of the coil would form 1 side of a traingle, the pitch of the coil a second side, and the length of the coil would be the Hypotenuse. Thus from pitch and diameter the length can be calculated.