415.11.6.3 Excess flow control.

Where HPM gases or liquids are carried in pressurized piping above 15 pounds per square inch gauge (psig) (103.4 kPa), excess flow control shall be provided. Where the piping originates from within a liquid storage room, HPM room or gas room, the excess flow control shall be located within the liquid storage room, HPM room or gas room. Where the piping originates from a bulk source, the excess flow control shall be located as close to the bulk source as practical.

415.11.6.4 Installations in corridors and above other occupancies.

The installation of HPM piping and tubing within the space defined by the walls of exit access corridors and the floor or roof above or in concealed spaces above other occupancies shall be in accordance with Sections 415.11.6.1 through 415.11.6.3 and the following conditions:

   1.   Automatic sprinklers shall be installed within the space unless the space is less than 6 inches (152 mm) in the least dimension.

   2.   Ventilation not less than six air changes per hour shall be provided. The space shall not be used to convey air from any other area.

   3.   Where the piping or tubing is used to transport HPM liquids, a receptor shall be installed below such piping or tubing. The receptor shall be designed to collect any discharge or leakage and drain it to an approved location. The 1-hour enclosure shall not be used as part of the receptor.

   4.   HHPM supply piping and tubing and nonmetallic waste lines shall be separated from the corridor and from occupancies other than Group H-5 by fire barriers or by an approved method or assembly that has a fire-resistance rating of not less than 1 hour. Access openings into the enclosure shall be protected by approved fire-resistance- rated assemblies.

   5.   Readily accessible manual or automatic remotely activated fail-safe emergency shutoff valves shall be installed on piping and tubing other than waste lines at the following locations:

      5.1.   At branch connections into the fabrication area.

      5.2.   At entries into exit access corridors.

   Exception: Transverse crossings of the corridors by supply piping that is enclosed within a ferrous pipe or tube for the width of the corridor need not comply with Items 1 through 5.

415.11.6.5 Identification.

Piping, tubing and HPM waste lines shall be identified in accordance with ANSI A13.1 to indicate the material being transported.

415.11.7 Continuous gas detection systems.

A continuous gas detection system shall be provided for HPM gases where the physiological warning threshold level of the gas is at a higher level than the accepted permissible exposure limit (PEL) for the gas and for flammable gases in accordance with Sections 415.11.7.1 and 415.11.7.2.

415.11.7.1 Where required.

A continuous gas detection system shall be provided in the areas identified in Sections 415.11.7.1.1 through 415.11.7.1.4.