Current through Register Vol. 47, No. 17, September 10, 2024
This Section applies specifically to systems mounted on
trucks, semi-trailers and trailers (other than those covered under Sections 10
and 11) used for the transportation of ammonia. All General Rules of Section 2
apply to this Section 9 unless otherwise noted.
9.1.
Design Pressure of
Containers
9.1.1. Containers shall be
constructed in accordance with Rule 3.1 with a minimum design pressure of 250
psig.
9.1.2. The shell or head
thickness of any container shall not be less than 3/16 inch.
9.1.3. All container openings, except safety
relief valves, liquid level gauging devices and pressure gauges, shall be
labeled to designate whether they communicate with liquid or vapor space.
Labels may be on valves.
9.1.4.
Baffles are not required for cargo tanks.
9.2.
Mounting Containers on
Truck
9.2.1. The means of attachment
of any container to the cradle, frame or chassis of a vehicle shall be designed
on a basis of two "g" loading in either direction, using a safety factor of not
less than 4, based on the ultimate strength of the material used. For purposes
of this requirement, two "g" of load support is equivalent to three times the
static weight of the articles supported; two "g" of loading and bending,
acceleration, and torsion is equivalent to twice the static weight support
applied horizontally at the road surface.
9.2.2. "Hold-down" devices, when used, shall
anchor the container to the cradle, frame or chassis in a suitable and safe
manner that will not introduce undue concentration of stresses. These devices
shall incorporate positive means for drawing the container down tight, and
suitable stops or anchors shall be provided to prevent relative movement
between container and framing due to stopping, starting or changes in
direction.
9.2.3. Vehicles designed
and constructed so that the cargo tanks constitute in whole or in part the
stress member used in lieu of the frame shall be supported by external cradles
suspending at least 120° of the shell circumference. The design calculation
shall include beam stress, shear stress, torsion stress, bending moment and
acceleration stress, in addition to those covered by the code under which the
cargo tank was designed.
9.2.4. If
a liquid withdrawal line is installed in the bottom of a container, the
connections thereto, including hose, shall not be lower than the lowest
horizontal edge of the trailer axle.
9.2.5. Provisions shall be made to secure
both ends of the hose while in transit.
9.2.6. When the cradle and the container are
not welded together, suitable material shall be used between them to eliminate
metal-to-metal friction.
9.3.
Container Appurtenances
9.3.1. Non-recessed container fittings and
appurtenances shall be protected against physical damage by either:
(1) a protected location,
(2) the vehicle frame or bumper, or
(3) a protective housing. The protective
housing, if used, shall comply with the requirements under which the containers
are fabricated with respect to design and construction, and shall be designed
to withstand static loadings in any direction equal to twice the weight of the
container and attachments when filled with the lading using a safety factor of
not less than 4, based on the ultimate strength of the material to be used. The
protective housing if used shall be protected with a weather cover, if
necessary, to ensure proper operation of valves and safety relief
devices.
9.3.2. All
connections to containers, except filling connections (see 9.3.3), safety
relief devices, and liquid level and pressure gauge connections, shall be
provided with suitable automatic excess flow valves, or in lieu thereof, may be
fitted with quick-closing internal valves, which shall remain closed except
during delivery operations. The control mechanism for such valves may be
provided with a secondary control remote from the delivery connections and such
control mechanism shall be provided with a fusible section (melting point
208ºF to 220ºF) which will permit the internal valve to close
automatically in case of fire.
9.3.3. Filling connections shall be provided
with automatic back-pressure check valves, excess-flow check valves, or
quick-closing internal valves, to prevent back-flow in case the filling
connection is broken. Where the filling and discharge connect to a common
opening in the container shell and that opening is fitted with a quick-closing
internal valve as specified in 9.3.2, the automatic valve shall not be
required.
9.3.4. All containers
shall be equipped for spray loading (filling in the vapor space) or with an
approved vapor return valve of adequate capacity.
9.3.5. All containers shall be equipped with
a fixed maximum liquid level gauge.
9.3.6. All containers shall be equipped with
a pressure-indicating gauge having a dial graduated from 0-400 psig.
9.4.
Piping and
Fittings
9.4.1. All piping, tubing and
fittings shall be securely mounted and protected against physical
damage.
9.4.2. Piping used on
non-refrigerated systems shall be at least ASTM A-53 Grade B Electric
Resistance Welded and Electric Flash Welded Pipe or equal. Such pipe shall be
at least Schedule 40 when joints are welded, or welded and flanged. Such pipe
shall be at least Schedule 80 when joints are threaded. Brass, copper, or
galvanized steel pipe or tubing shall not be used.
9.4.3. The truck unloading line shall be
provided with an excess flow valve at the hose connection unless an approved
quick dosing internal valve is provided in the container unloading connection.
(See 9.3.2)
9.5.
Safety Relief Devices
9.5.1. The
discharge from container safety relief valves shall be vented away from the
container upward and unobstructed to the open air in such a manner as to
prevent any impingement of escaping gas upon the container; loose fitting rain
caps shall be used. Size of discharge lines from safety relief valves shall not
be smaller than the nominal size of the safety relief valve outlet connection.
Suitable provision shall be made for draining condensate which may accumulate
in the discharge pipe.
9.6.
Marking of Container
9.6.1. Every container, whether loaded or
empty, shall be conspicuously and legibly marked on each side and rear thereof
on a background of sharply contrasting color with the words "COMPRESSED GAS" in
letters at least four inches high; and with the words "ANHYDROUS AMMONIA" in
letters at least four inches high.
9.7.
Transfer of Liquids
9.7.1. The content of tank motor vehicle
containers shall be determined by weight, or suitable metering device.
NOTE: If the content of a container is to be determined by
liquid level measurement, the container shall have a thermometer well so that
the internal liquid temperature can be easily determined. This volume when
converted to weight shall not exceed the filling density.
9.7.2. Pumps or compressors shall be designed
and installed in accordance with Rule 6.4 and protected against physical damage
when mounted upon ammonia tank trucks and trailers.
9.7.3. Tank motor vehicles of greater than
3500 water gallons capacity shall be unloaded only at approved locations
meeting the requirements of Rules 6.2.3 and 6.4.8.
9.8.
Trailers and Semi-Trailers
9.8.1. Trailers shall be firmly and securely
attached to the vehicle drawing them by means of suitable drawbars,
supplemented by suitable safety chain (or chains) or safety cables.
9.8.2. Every trailer and semi-trailer shall
be equipped with an emergency braking system to be activated in the event of
hitch failure.
9.8.3. Trailers
shall be of a type of construction which will prevent the towed vehicle from
whipping or swerving dangerously from side to side and which will cause it to
follow substantially in the path of the towing vehicle.
9.8.4. Where a fifth wheel is employed on a
semi-trailer, it shall be ruggedly designed, securely fastened to both units,
and equipped with a positive locking mechanism which will prevent separation of
the two units except by manual release.
9.8.5. Every trailer or semi-trailer shall be
provided with side lights and a tail light.
9.9.
Electrical Equipment and
Lighting
9.9.1. Tank trucks, tank
trailers, and tank semi-trailers, may not be equipped with any artificial light
other than electric light. Electric lighting circuits shall have suitable
overcurrent protection (fuses or automatic circuit breakers). The wiring shall
have sufficient carrying capacity and mechanical strength, and shall be
suitably secured, insulated and protected against physical damage.
9.10.
Protection Against
Collision
9.10.1. Each tank motor
vehicle shall be provided with properly attached bumpers or chassis extensions
arranged to protect the tank, piping, valves and fittings from physical damage
in case of collision.
9.11.
Chock Blocks
9.11.1. At least two chock blocks shall be
provided. These blocks shall be placed to prevent rolling of the vehicle
whenever it is parked during loading and unloading operations.
9.12.
Portable Tanks
(Including Skid Tanks)
9.12.1. When
portable tanks are used in lieu of cargo tanks and are permanently mounted on
tank motor vehicles for the transportation of ammonia, they shall comply with
the requirements of Section 9. Where portable tanks, including those built to
DOT Specification 51, 106A or 110A, are used for farm storage they shall comply
with Section 7. When portable tanks are used as shipping containers in
interstate commerce they shall comply with Section 8.
9.13.
Safety Equipment
9.13.1. All tank trucks, trailers, and
semitrailers shall be equipped with the following:
9.13.1.1. One full face gas mask with
anhydrous ammonia refill canisters.
9.13.1.2. One pair of protective gloves made
of rubber or other material impervious to ammonia.
9.13.1.3. Tight-fitting goggles or one full
face shield.
9.13.1.4. A container
of not less than five gallons of readily available clean water.
*An ammonia canister is effective for short periods of time
in light concentrations of ammonia vapor, generally 15 minutes in
concentrations of 3% and will not protect breathing in heavier concentrations.
If ammonia vapors are detected when mask is applied the concentration is too
high for safety. The life of a canister in service is controlled by the
percentage of vapors to which it is exposed. Canisters must not be opened until
ready for use and should be discarded after use. Unopened canisters may be
guaranteed for as long as three years. All should be dated when received
because of this limited life. In addition to this protection, an independently
supplied air mask of the type used by fire departments may be used for severe
emergencies.