Regulations of Connecticut State Agencies
Sectionalizing valves (block valves) shall be installed and maintained at strategic points on the pipe lines system at an average of not less than one valve for each five miles of pipe line in Class 4 locations and one valve for each eight miles in Class 1, 2 or 3 locations with due regard to accessibiity and the possible necessity for limiting a discharge of gas in the event of failure or an emergency. Such valves shall be protected from damage and tampering. In all installations, an operating device such as a suitable handwheel or wrench to open or close the valve shall be readily accessible to authorized persons.