looking for copper tube for UK designed boilers in US

[kbec6]

I was wondering if anyone knows a good way to get the copper tubing specified in the British designs in the US. The designs specify the OD where much of what I can find here is measured by the ID.

 

[IceFyre13th]

http://www.onlinemetals.com/

Is a place I found for some of the sizes of tubing as well as sheet and bar stock.