BEST PRACTICES FOR THE STORAGE OF AMMONIUM NITRATE
References Related to Best Practices –
Storage of Ammonium Nitrate
Please
check with your local jurisdiction having authority to determine if there is a
local fire code or other regulatory code that must be utilized related to
storage of ammonium nitrate.
Occupational
Safety and Health Administration (OSHA)
OSHA
Standard 1910.109(i)(4) also defines additional requirements for storage of
ammonium nitrate. The following are some, but not all the requirements:
1910.109(i)(5)(i)(a):
“Ammonium nitrate shall be in a separate building or shall be separated by
approved type firewalls of not less than 1-hour fire-resistance rating from
storage of organic chemicals, acids, or other corrosive materials…”.
1910.109(i)(5)(i)(b):
“In lieu of separation walls, ammonium nitrate may be separated from the
materials referred to in paragraph (a) of this section by a space of at least
30 feet”.
1910.109(i)(6)(i):
“Electrical installations shall conform to the requirements of subpart S of
this part, for ordinary locations. They shall be designed to minimize damage
from corrosion”.
1910.109(i)(7)(ii)(a):
“Water supplies and fire hydrants shall be available in accordance with
recognized good practices”.
The
U.S. Senate Committee on Environment and Public Works held a hearing on June
27th in Washington, D.C., and various experts from the Chemical Safety Board,
Department of Homeland Security, Texas A&M University, and others all
agreed with Chairperson Boxer that fire must be prevented from reaching bulk
storage of ammonium nitrate. Some recommendations included:
- Storage of ammonium nitrate in non-combustible storage facilities or at least have a one-hour fire barrier separating a storage bin of ammonium nitrate from other adjacent products
- Fire sprinklers suitable for a corrosive atmosphere
- Third party inspection of these facilities should be in place (i.e. insurance companies insuring these facilities, safety institutes, etc.)
NFPA
400 Hazardous Materials Code, 2013 Edition, Chapter 11 (Please refer to the
entire standard. Below are some highlights from this NFPA standard and not inclusive
of everything in this document).
Ammonium nitrate is rated as a Class 2
Oxidizer and a Class 3 Unstable Reactive requiring automatic fire sprinklers
per 6.2.1.1
Portable extinguishers shall be
provided throughout
the storage area and in the loading and
unloading areas in
accordance with the fire prevention
code adopted by the jurisdiction
and NFPA 10, Standard for Portable
Fire Extinguishers.
Separation.
Ammonium nitrate shall be separated by
fire barrier
walls of not less than 1-hour fire resistance
or located in a
separate building from the storage of
any of the following:
(1) Organic chemicals, acids, or other
corrosive materials
(2) Compressed flammable gases
(3) Flammable and combustible
materials, solids or liquids
(4) Other contaminating substances,
including the following:
(a) Wood chips
(b) Organic materials
(c) Chlorides
(d) Phosphorus
(e) Finely divided metals
(f) Charcoals
(g) Diesel fuels and oils
Walls referred to in 11.2.12.1.1 shall
extend from
the floor to the underside of the roof
above.
In lieu of fire barrier walls, ammonium
nitrate
shall be permitted to be separated from
the materials referred
to in 11.2.12.1.1 by a space of at
least 30 ft (9.1 m) or more, as
required by the AHJ, and sills or curbs
shall be provided to
prevent mixing during fire conditions.
Incompatible Materials.
Flammable liquids, such as gasoline,
kerosene,
solvents, and light fuel oils, shall
not be stored on the premises,
unless the following criteria are met:
(1) The storage conforms to NFPA 30, Flammable
and Combustible
Liquids Code.
(2) Walls and sills or curbs are
provided in accordance with
11.2.12.1.1 through 11.2.12.1.3.
LP-Gas shall not be stored on the
premises, unless
such storage conforms to NFPA58, Liquefied
Petroleum Gas Code.
Indoor Storage.
Storage Conditions/Arrangement. Storage arrangement
shall be in accordance with 11.3.2.1
through 11.3.2.3.
Containers. Bags and containers used for ammonium
nitrate shall comply with the
specifications and standards established
by the U.S. Department of
Transportation (DOT).
Piles of Bags, Drums, or Other
Containers.
Containers of solid ammonium nitrate
shall not be
placed into storage when the
temperature of the ammonium
nitrate exceeds 130°F (54.4°C).
Bags of ammonium nitrate shall not be
stored
within 30 in. (762 mm) of the walls and
partitions of the storage
building.
Piles shall comply with the following
dimensions:
(1) The height of piles shall not exceed
20 ft (6.1 m).
(2) The width of piles shall not exceed
20 ft (6.1 m).
(3) The length of piles shall not
exceed 50 ft (15.2 m), unless
otherwise permitted by 11.3.2.2.3(4).
(4) Where the building is of
noncombustible construction, or
is protected by automatic sprinklers,
the length of piles
shall not be limited.
In no case shall the ammonium nitrate
be stacked
closer than 3 ft (0.9 m) below the roof
or its supporting overhead
structure.
Aisles shall be provided to separate
piles by a clear
space of not less than 3 ft (0.9 m) in
width, with at least one
service or main aisle in the storage
area not less than 4 ft (1.2 m)
in width.
Piles of Bulk Solid Storage.
Warehouses shall have ventilation, or
be capable of
ventilation in case of fire, that will,
in the event of a fire, prevent
the explosive decomposition of ammonium
nitrate.
Buildings shall be ventilated so as to
prevent confinement
of decomposition gases.
Bulk storage structures shall not
exceed a height of
40 ft (12.2 m).
Where bulk storage structures are
constructed of
noncombustible material and facilities
for fighting a roof fire
are provided, the height of the storage
building shall only be
limited by the building construction
type as specified in the
building code adopted by the
jurisdiction.
Compartments.
Bins shall be clean and free of
materials that can
contaminate ammonium nitrate.
Due to the corrosive and reactive
properties of ammonium
nitrate, and to avoid contamination,
galvanized iron,
copper, lead, and zinc shall not be
used in bin construction, except
where such bins are protected against
impregnation by ammonium
nitrate.
Aluminum bins, and wooden bins
protected
against impregnation by ammonium
nitrate, shall be permitted.
The warehouse shall be permitted to be
subdivided
into any desired number of ammonium
nitrate storage
compartments or bins.
The partitions dividing the ammonium nitrate storage
from the storage of other products that would contaminate
the ammonium nitrate shall be constructed to prevent
the ammonium nitrate from becoming contaminated.
The ammonium nitrate storage bins or piles shall
be clearly identified by signs reading AMMONIUM NITRATE
with letters at least 2 in. (50.8 mm) high.
Piles or bins shall be sized and arranged so that
all material in the pile is able to be moved out in order to
minimize possible caking of the stored ammonium nitrate.
The height or depth of piles shall be limited by
the pressure-setting tendency of the product; however, in no
case shall the ammonium nitrate be piled higher at any point
than 3 ft (0.9 m) below the roof or its supporting and overhead
structure.
Ammonium nitrate shall not be placed into storage
when the temperature of the product exceeds 130°F (54.4°C).
Dynamite, other explosives, and blasting agents
shall not be used to break up or loosen caked ammonium nitrate.
Floors.
All flooring in storage and handling areas shall be
without open drains, traps, tunnels, pits, or pockets into which
any molten ammonium nitrate is able to flow and be confined
in the event of fire.
Note: This is not an all
inclusive list of best practices related to storage of ammonium nitrate, but is
provided to provide highlights from three resources to facilitate further
research by the property manager and/or owner.
