Sorry to say but I believe you need far more help than can be offered here at least with as broad as your question covers. To many attributes.

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