What is the Outside diameter for schedule 40 pipe?

That all depends on the size of the schedule 40 pipe! It comes in diameters as small as 1/2 in all the way to 26 inches. That would be the inside diameter.

Bevel inside of sch. 80 to match OD of sch. 40

It is the wall thickness heavier then schedule 20 lighter then schedule 80

Thicker pipe wall is required to contain higher fluid pressures. For the same fluid pressure, a thicker pipe wall is required for a larger diameter pipe than that required for a pipe of smaller...

5,000,000 feet? Of 6"