Bursting Pressures of Rectangular Tubing 1

[BigJonnyC]

I'm a mechanical engineering co-op at a firm that manufactures industrial cleaning machines. We are currently trying to compare round piping to rectangular tubing on a cost versus strength basis. The pipes/tubes are to have half couplings welded to them for the installation of spray nozzles with water pressures ranging from 40 to over 1000 PSI. As it is easier to drill and weld on the broad face of the rectangular tubing we would like to see if it is also cost effective. My problem is that I'm having trouble doing a stress analysis on an internally pressurized length of rectangular tubing. I am unsure of how to take into account the stress concentrations that will occur at the rounded corners. If anyone can help it would be greatly appreciated. Thanks.

 

[arto]

Look @ ASME Boiler & Pressure Vessel Code App. 13 for non-circular pressure vessels.

The stress is all membrane in a pipe, but bending is significant in rect. tube. [= heavier construction]

One benefit of using it for c.st'l. structural work unpressurized] is the 46ksi yield for ASTM A-500-B.


Swepco makes Sq. tube:

http://www.swepcotube.com/product_design.html

 

[bvi]

It sounds like you have a round hole drilled in a square bar, in which case none of the code formulae apply. You can probably size the thickness using the cylindrical tube formula and comparing the required thickness for that confiruation to the minimum thickness you have in this configuration, but I would consider to a confirmatory FEA, in particular in case you were worried about stress concentration effects and pressure cycling fatigue.