DaviD - "it's rodular." - Rodular ?
Do You Mean : Round Metal Rod Stock ?
-or- a Round Metal Rod Blank ?

DaviD - a pipe, Is A Pipe. IS A PIPE ! :
a Hollow Cylinder some times called a Tube.

A Solid Copper Pipe refers to :
'a' Solid {The Nature of the Material} Copper
in the form of a Pipe. The Metal is All Copper
Material.

A PVC Pipe is made of a plastic "PVC" Material.

A Copper "Clad" Metal Pipe : Would be a Pipe made
of Metal Materials with a Outer Surface of Copper.

pipe are Pipe the World Around -and- anyway you
look at it the World is Round - since it is basically
a Sphere {Ball} "Globe" .

DaviD - Some people say - Pie Are Square ;-}
Then Again most people say - Cakes are Square
and Pies are Round )

DaviD - I Am Not Trying To Confuse 'you' - That's 'your' Job !

david - i am glad we had this little chat ~ RHF