49 CFR §192.167

1. (a)Except for unattended field compressor stations of 1,000 horsepower (746 kilowatts) or less, each compressor station must have an emergency shutdown system that meets the following:
   1. (1)It must be able to block gas out of the station and blow down the station piping.
   2. (2)It must discharge gas from the blowdown piping at a location where the gas will not create a hazard.
   3. (3)It must provide means for the shutdown of gas compressing equipment, gas fires, and electrical facilities in the vicinity of gas headers and in the compressor building, except that:
      1. (i)Electrical circuits that supply emergency lighting required to assist station personnel in evacuating the compressor building and the area in the vicinity of the gas headers must remain energized; and
      2. (ii)Electrical circuits needed to protect equipment from damage may remain energized.
   4. (4)It must be operable from at least two locations, each of which is:
      1. (i)Outside the gas area of the station;
      2. (ii)Near the exit gates, if the station is fenced, or near emergency exits, if not fenced; and
      3. (iii)Not more than 500 feet (153 meters) from the limits of the station.
2. (b)If a compressor station supplies gas directly to a distribution system with no other adequate source of gas available, the emergency shutdown system must be designed so that it will not function at the wrong time and cause an unintended outage on the distribution system.
3. (c)On a platform located offshore or in inland navigable waters, the emergency shutdown system must be designed and installed to actuate automatically by each of the following events:
   1. (1)In the case of an unattended compressor station:
      1. (i)When the gas pressure equals the maximum allowable operating pressure plus 15 percent; or
      2. (ii)When an uncontrolled fire occurs on the platform; and
   2. (2)In the case of a compressor station in a building:
      1. (i)When an uncontrolled fire occurs in the building; or
      2. (ii)When the concentration of gas in air reaches 50 percent or more of the lower explosive limit in a building which has a source of ignition.