5706.5.7 Static protection.

Static protection shall be provided to prevent the accumulation of static charges during transfer operations. Bonding facilities shall be provided during the transfer through open domes where flammable liquids are transferred, or where combustible liquids are transferred into cargo tanks or tank cars which could contain vapors from previous cargoes of flammable liquids. Protection shall consist of a metallic bond wire permanently electrically connected to the fill stem. The fill pipe assembly shall form a continuous electrically conductive path downstream from the point of bonding. The free end of such bond wire shall be provided with a clamp or equivalent device for convenient attachment to a metallic part in electrical contact with the cargo tank or tank car. For cargo tanks, protection shall consist of a flexible bond wire of adequate strength for the intended service and the electrical resistance shall not exceed 1 megohm. For tank cars, bonding shall be provided where the resistance of a tank car to ground through the rails is 25 ohms or greater. Such bonding connection shall be fastened to the cargo tank or tank car before dome covers are raised and shall remain in place until filling is complete and all dome covers have been closed and secured.

   Exceptions:

   1.   Where cargo tanks or tank cars are loaded exclusively with products not having a static-accumulating tendency, such as asphalt, cutback asphalt, most crude oils, residual oils and water-miscible liquids.

   2.   When flammable liquids are not handled at the transfer facility and the cargo tanks are used exclusively for combustible liquids.

   3.   Where cargo tanks or tank cars are loaded or unloaded through closed top or bottom connections when the hose is conductive.

5706.5.7.1 Filling through open domes.

Filling through open domes into the tanks of cargo tanks or tank cars that contain vapor-air mixtures within the flammable range, or where the liquid being filled can form such a mixture, shall be by means of a downspout which extends to near the bottom of the tank. It shall be unlawful to fill a cargo tank or tank car with gasoline through an open dome.

5706.5.8 Stray current protection.

Tank car loading facilities where Class I, II or IIIA liquids are transferred through open domes shall be protected against stray currents by permanently bonding the pipe to at least one rail and to the transfer apparatus. Multiple pipes entering the transfer areas shall be permanently electrically bonded together. In areas where excessive stray currents are known to exist, all pipes entering the transfer area shall be provided with insulating sections to isolate electrically the transfer apparatus from the pipelines.

5706.5.9 Top loading.

When top loading a cargo tank with Class I and II liquids without vapor control, valves used for the final control of flow shall be of the self-closing type and shall be manually held open except where automatic means are provided for shutting off the flow when the tank is full. When used, automatic shutoff systems shall be provided with a manual shutoff valve located at a safe distance from the loading nozzle to stop the flow if the automatic system fails. When top loading a cargo tank with vapor control, flow control shall be in accordance with FC 5706.5.10. Self-closing valves shall not be tied or locked in the open position.

5706.5.10 Bottom loading.

When bottom loading a cargo tank or tank car with or without vapor control, a positive means shall be provided for loading a predetermined quantity of liquid, together with an automatic secondary shutoff control to prevent overfill. The connecting components between the transfer equipment and the cargo tank or tank car required to operate the secondary control shall be functionally compatible.