The peel test is to check for voids in the brazed joint.
In the case of pipe, the joint is always a lap joint that is in the shape of a socket fitting. The peel test is performed like it would be for any lap join, just cut the pipe into quadrants so you can work it easier.
If you are operating as an independent operator, you need the references. It is a part of doing business. You cannot deliver sand if you do not own a dump truck. Same principal works in this business.
AWS has a standard for testing brazed joints.
Best regards - Al