Internal sizes of copper and equivalently sized barrell

[Mickyplumb]

Guys, is there anywhere I can look to find for example the exact internal diameter of 2 inch copper and 2 inch iron ??

 

[on31ll]

Get some and a micrometer ?

 

[Mike Jackson]

Copper tube is measured by the outside diameter have a look at Yorkex | Yorkshire Copper Tube for wall diameters of half hard copper (table X).

Black iron is measured by the internal diameter so 2" black iron will have an internal diameter of 2" and 54mm copper an ID of 51.6mm.