[nineoneone]

I worked with some years ago and from what I remember it was the crimp ring type that gave the most problems. Two types, nut ,cone and washer and or crimp ring. Nut ,cone and washer is like a compression fitting and the crimp was a copper ring around the pipe with a smaller piece of pipe inside the pb pipe to keep it from crushing. The outer ring was crimped on and that was the problem. No one could figure out how much pressure was needed Not to break the interior pipe, thus leaks... nut cone washer held up good. I thought the restriction was on underground pb. It had a tendency (sp)to move and come apart under ground.