PART H - INSPECTION OF RAIL CARS
Cars are inspected for suitability of use, proper documentation, and security seals. Generally, a petroleum
rail car has only one compartment; however, some have more than one compartment and can carry multi-
products. Cars are manufactured from different gages of steel depending on usage and may be equipped
with heaters to liquefy highly viscous product. Typically each compartment has a bottom outlet. In the U.S.
5-inch outlets are standard; overseas 4-inch outlets are standard. Each compartment has a dome through
which the rail car may be loaded, unloaded, inspected, cleaned, and repaired. The dome provides room for
expansion of product in the event of temperature rise and may be hinged and bolted or screwed on. The
tank car is also equipped with a safety valve. The safety valve used on most tank cars consists of a poppet
valve, spring-loaded to predetermined pressure. As pressure develops in the dome and increases to a point
in excess of the pressure setting of the valve, the valve is forced off the valve seat, thereby permitting
excess vapor to escape. When the pressure drops to a level equal to the valve setting, the spring closes the
valve automatically.
PART I - LOADING AND UNLOADING OF RAIL TANK CARS
The minimum distance from a tank car loading operation to a building should be 100 feet. A spur track or
bypass should be provided for loading or unloading tank cars. Trackage should be level to maintain equal
depth of product throughout the tank car compartments. Level trackage is necessary for accurate gaging of
the tank and to prevent air from being trapped at one end of a tank when the tank is closed. The site should
provide adequate drainage. Bond and ground the car with a minimum of four cables. Derails should be
installed at the head of the siding to prevent other cars from backing into the siding during transfer
operations. A metal derail is approximately 18 inches long; the forward or flat portion is about 6 inches long
and the rear or wedge shaped portion, about 12 inches long. It is attached to the top of one rail of the track.
The 6 inch portion lays flat on the track, and the wedge-shaped portion gradually elevates to a height of
about 1-foot 1/4 inch to either stop or derail the first car of a train backing into the siding. Some derails,
designed in a similar manner, are made of wood. Derails may also be installed at other locations to prevent
cars from rolling into danger areas if the brakes are released accidentally or fail to hold. Where derails are
provided, they must be set and locked or operated so that they furnish the protection intended.
PART J - LOADING/UNLOADING FACILITIES AND EQUIPMENT
Where more than one filling point is used, loading racks should be spaced to allow several cars to be loaded
at one time. Each filling point should be grounded and should be equipped with bonding cables for bonding
the filling point to the tank car shell and to the track. A flexible hose long enough to reach the bottom of the
tank should be connected to the outlet of the loading arm. An emergency valve should be located some
distance from the rack so that the line can be cut off in case of fire at the loading rack. Loading racks may
be supplied with product directly from bulk storage tanks or pipelines by gravity flow, or fixed or portable
pumping units may be used to transfer product. A distribution manifold, consisting of necessary piping and
valves, extends along the loading rack and provides outlets for loading and unloading several cars at one
time. Flexible hose lengths should be provided to permit loading cars through the domes. Manifolds must
be grounded and equipped with cable for bonding the manifold to the track and to the tank car. A standard
car mover should be provided for spotting tank cars. Electrical equipment operating in the area, such as
lights, switches, and motors, must be of explosion-proof construction and must be in good working condition.
A wooden cone-shaped plug, suitable for plugging the bottom outlet of the tank car, should be available in
case of an emergency. The pump assembly must be positioned a minimum of 50 feet away from rail car.
3-11
QM 5098
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