I suppose it should be easier to find if I know what it's called! BG
Thanks Harold.

You aren't looking for pipe, you're looking for tubing. Tubing is
available
in a multitude of wall thicknesses and outside diameters, so you should be
able to find what you're looking for, made of 4130, which is readily heat
treatable. Check in your yellow pages to see if you have such a
supplier
locally. Keystone Marmon is one of them, but there are others, including
Jorgensen.

Harold