How to butt weld 2 pipes together straight?

If you have a sander/grinder, you can take the galvi off that way.

If you're going to weld pipe I suggest what's already been suggested.....V groove it.

The joint should look like this ______/\______

You should get complete joint penetration that way and it should never break.

Oh, put a minimum 1/16" root opening; maximum 3/16"....depending on pipe size.