Don't know what process your going to use but the standard gap is 3/32" to 1/8" with no land up to an 1/8" land. The test coupons with be taken from 2 o'clock, 4 o'clock, 8 o'clock and 10 o'clock. Schedule 40 6" pipe with be 2-face bends and 2-root bends. Schedule 80 6" or 8" schedule 40 pipe will be side bends. Just a quick overview.
Regards, Jerry