Third Edition

Top Fittings Protection Requirements for
Tank Cars Transporting Materials
Poisonous (Toxic) by Inhalation
(PIH/TIH Materials)
As mentioned in Section 1: Tank Car Classification and
Specifications, the U. S. DOT issued new rules in January
2009 requiring enhanced safety measures for tank cars
transporting PIH/TIH materials.
A tank car built after March 16, 2009, for the
transportation of a PIH/TIH material, must have the
service equipment enclosed within a protective housing
and cover.
In addition, it must be equipped with a top fittings
protection system and nozzle capable of sustaining,
without failure, a rollover accident at a speed of 9 miles
per hour, in which the rolling protective housing strikes
a stationary surface assumed to be flat, level, and rigid.
Failure is deemed to occur when the deformed
protective housing contacts any of the service
equipment, or when the tank retention capability is
compromised.
As an alternative to the above top fittings protection,
the tank may be equipped with a system that prevents the
release of the product from any top fitting in the case of
an accident where any fitting would be sheared off (i.e.,
“Enhanced Fittings Package for PIH/TIH Tank Cars).
See the illustrations on pages 87-89 for examples of these
devices.
Enhanced Fittings Package for
PIH/TIH Tank Cars
A coalition of tank car and valve manufacturers, chemical
producers, and railroads researched tank car design
criteria to improve transportation safety of PIH/TIH
materials, primarily chlorine. This research project was
referred to as the “Next Generation Rail Tank Car
(“NGRTC” or “Next-Gen”) Project”.
In addition to added safety features to the tank car
structure itself, an enhanced fittings package has been
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