N.Y. Comp. Codes R. & Regs. tit. 16, § 255.179 – Valves on pipelines to operate at 125 psig (862 kPa) or more.

(a) Each pipeline to operate at 125 psig (862 kPa) or more must have sectionalizing block valves spaced according to the following:
1. (1) Each point on the pipeline in a Class 4 location must be within ½ mile (0.805 kilometer) of a valve.
2. (2) Each point on the pipeline in a Class 3 location must be within two miles (3.22 kilometers) of a valve.
3. (3) Each point on the pipeline in a Class 2 location must be within 3½ miles (5.63 kilometers) of a valve.
4. (4) Each point on the pipeline in a Class 1 location must be within five miles (8.05 kilometers) of a valve.
(b) Each sectionalizing block valve and operating device on a pipeline to operate at 125 psig (86.2 kPa) or more must:
1. (1) be readily accessible and protected from tampering and damage; and
2. (2) be supported to prevent settling of the valve or movement of the pipe to which it is attached.
(c) Each section of a pipeline to operate at 125 psig (862 kPa) or more must have a blow-down valve with enough capacity to allow the line to be blown down as rapidly as practicable or other approved means to reduce the pressure.
(d) Each blow-down discharge must be located so the gas can be blown to the atmosphere without hazard and, if the line is adjacent to an overhead electric line, so that the gas is directed away from the electrical conductors.