4.12.707 CONTAINER APPURTENANCES
(1) All appurtenances shall be designed for not less than the maximum working pressure of that portion of the system on which they are installed. All appurtenances shall be fabricated from materials suitable for use in anhydrous ammonia service.
(2) All connections to containers, except safety relief connections and gauging devices, shall have shutoff valves located as close to the container as practicable.
(3) Liquid level gauging devices, which are so constructed that outward flow of container content shall not exceed that passed by a No. 54 drill size opening, need not be equipped with excess flow valves.
(4) Container openings or through fittings (directly on container and used for pressure gauge connections) need not be equipped with excess flow valves if such openings are protected by a vent hole not larger than a No. 54 drill size hole.
(5) All excess flow valves shall be clearly and permanently marked with the name or trademark of the manufacturer, the catalog number, and the rated capacity.
(6) Excess flow valves shall close automatically at the vapor or liquid rated flows as specified by the manufacturer. The connections and line, including appurtenances being protected by an excess flow valve, shall have a greater capacity than the rated flow of the excess flow valve so the valve will close in case of failure at any point in the line or fittings.
(7) Excess flow and back pressure check valves shall be located inside the container or at a point outside where the line enters the container. In the latter case, installation shall be made in such a manner that any undue strain, beyond the excess flow or back pressure check valve, will not cause breakage between the container and the excess flow valve.
(8) Excess flow valves shall be designed with a by-pass, not to exceed a No. 60 drill size opening, to allow equalization of pressure.