What does the “DR” or “SDR” number on the pipe mean?
It is the ratio of pipe diameter to wall thickness. It is calculated by dividing the specified outside diameter of the pipe by the minimum specified wall thickness. Any size pipe with a common DR is qualified to operate at the same pressure regardless of pipe OD (e.g. 2″ IPS DR 11 pipe can have the same operating pressure as 12″ DR 11).
