Top fittings on tank cars may vary in design and position. NorFalco cars have either conventional acid car top fittings or a new, low-profile design.

Low-Profile Top Fittings

• The top fittings on NorFalco acid cars, such as the rupture disc assembly, air valve and eduction pipe, have been shortened to enable the larger and more prominent fill hole nozzle to provide protection in the event of a derailment rollover. This protection is further enhanced by two steel side guard plates. Both the fill hole nozzle and side guard plates will absorb forces encountered during rollover, greatly reducing the risk of the fittings shearing off and releasing acid.

• The man-way cover and all mounted fittings and nozzles on new cars are made of 316 stainless steel for improved strength and corrosion protection. This change results in less corrosion, less leakage, reduced maintenance and easier customer hook-up. The design is being applied to all new and, where practical, existing tank cars.

• The eduction pipe cap has been redesigned to enable easier removal and better sealing. The new design uses a separate, coarser set of unified screw threads to attach the pipe cap, along with a cap gasket to provide a better in-transit seal. This leaves the finer standard 2" NPT pipe threads untouched by the pipe cap, and extends the life of these threads for easier hook-up by customer operators. To improve safety, the cap is also slotted in a way that directs latent pressure or product downwards before the cap is completely removed. The new design makes it easier to loosen the pipe cap on tapered pipe threads. Please note that the coarse threads (unified screw) do not need any lubricant, sealant or Teflon tape for tightening. In fact, such application will make the cap application more difficult.

• The NorFalco fleet standard for acid tank car gaskets is Viton B®. While more expensive than other gasket materials, this material has been shown to be the most effective for sulfuric acid tank cars.

• Top fittings and valves on NorFalco cars are centre mounted on or near the main man-way flange and surrounded by a full platform. This design provides convenient access for customer operators to make all required connections safely. The central location also helps reduce liquid sloshing impacts on rupture discs and gaskets.

• All cars are equipped with surge protectors, which are specialized devices mounted inside the tank car just under the rupture disc assembly. Surge protectors baffle the impact of sloshing acid caused by car movement. This baffling effect reduces liquid hammer pressures on the rupture disc, thus preventing premature failure and leaks.

• To eliminate risk of leakage through the washout flange and plug on the bottom of acid tank cars, we have eliminated the washout assembly on all new NorFalco tank cars. For existing cars, the washout cover is being removed and the opening welded shut.

• Fittings and flanges required for offloading can now be disassembled with one tool size. A 1⅝" socket head fits the fill hole cover nuts, the air valve plug, and the newly modified eduction pipe cap on all new and modified cars. A standard ratchet with extension can also be used.

Conventional Top Fittings
Conventional top fittings include:

1. A hinged fill hole and cover with a gasket seal.
2. A 2" or 3" discharge (eduction pipe) closed with a pipe cap.
3. A 1" air connection and pressure release valve.
4. A safety vent assembly containing a rupture disc assembly to protect the tank from excessive pressure (typically adjacent to fill hole). A surge arrestor or hydro damp under the safety vent assembly reduces the internal surge pressures at the safety relief device interface.
5. A washout plug and flange at the bottom of the tank car.
6. A gauge bar mounted inside the fill hole nozzle to gauge level when loading car.

Description of Tank Car Fittings
Fill Hole and Cover: An assembly consisting of an 8" to 10" opening on the dome of the tank to allow filling of the car and a hinged cover with a gasket compatible with the commodity to be transported. Covers are secured with swing bolts.

Eduction Pipe: The acid discharge pipe (also known as the siphon pipe or eduction pipe) running from the top of the car down inside, to a small sump on the bottom. The pipe top is closed with a cap attached to the car with a chain. This may be either 2" or 3" in diameter. NorFalco's fleet is changing to a standardized 2" thread on all low profile cars.

Rupture Disc: A 2" stainless steel frangible disc, as part of the top assembly. Approved by the Association of American Railroads, it must be compatible with the lading, and is designed to rupture at 33% of its tank burst pressure of 500 psi. Non-pressure sulfuric acid tank cars are equipped with 165 psi rupture discs.

Rupture Disc Assembly: A safety device consisting of an opening closed by a frangible disc designed to burst when enough pressure is applied from inside, thereby preventing distortion or other damage to the assembly. A cover, with locking pin, over the vent will direct discharging lading downward in the event of a ruptured disc. The disc does not close after bursting.

Air Inlet/Pressure Release Valve: An air connection to introduce compressed air to pressurize the car for unloading. On the conventional car, it is situated on the side of the rupture disc assembly. On low-profile cars, it is installed at a 45° angle on the man-way plate. It consists of a 1" valve with a plug, with the valve handle removed and attached to the car. This air connection is also used for depressurizing the car before hooking up hoses for unloading.

Bottom Washout Flange and Plug: A plug and blank flange situated on the bottom of a tank car. It is only used when cars are being cleaned in a shop for interior inspection and maintenance. On low-profile cars, the washout flanges and plugs are welded closed, or the cars have been fabricated with no washouts at all to help minimize any risk of leakage.