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Anhydrous Ammonia Bulk Storage Regulations (C.R.C., c. 1146)

Regulations are current to 2024-05-01 and last amended on 2015-06-18. Previous Versions

PART VSafety Relief Devices (continued)

 Safety relief valves and devices shall be inspected and tested prior to being put into service and shall be retested periodically as prescribed in the Compressed Gas Association pamphlet, Safety Relief Device Standards for Compressed Gas Storage Containers.

  •  (1) A safety relief valve venting to the outside atmosphere at a height not less than seven feet above ground level shall be installed between each pair of shut-off valves in an ammonia line where liquid may be trapped. The start to discharge pressure shall not be less than the setting of the container relief valve and not in excess of 400 psig.

  • (2) Sections of pipelines between shut-off valves and compressors, or shut-off valves and positive displacement pumps, shall be equipped with safety relief valves or bypasses set to discharge at a pressure not less than 240 psig and not over 400 psig.

 Each safety relief device shall be permanently marked or labelled by the manufacturer with the following information:

  • (a) start to discharge pressure in psig;

  • (b) full-open rate of discharge in c.f.m. of air at 60°F and 14.7 psia;

  • (c) letters “NH3” or “A.A.” to indicate its suitability for use in anhydrous ammonia service;

  • (d) manufacturer’s name or symbol;

  • (e) year of manufacture; and

  • (f) A.S.M.E. or Compressed Gas Association, or Underwriters’ Laboratories symbol.

PART VILoading and Unloading

  •  (1) The tank car, during loading or unloading operations, shall be protected on the connected end or ends of the siding by a sign of metal or other suitable material 12 inches by 15 inches in size and reading “STOP — TANK CAR CONNECTED”. The word “STOP” shall be in letters at least four inches high and the other words in letters at least two inches high and the letters shall be white on a blue background.

  • (2) The “STOP” sign shall be placed on the tank car or on the loading or unloading track in a manner that will ensure it is always visible to the crew of an engine on the same track.

  •  (1) At least one experienced operator supplied by the consignor or the consignee, as the case may be, shall supervise the loading or unloading operations, and during the absence of this operator from the installation site, loading or unloading shall be discontinued.

  • (2) During loading or unloading operations, tank car hand brakes shall be kept applied and the wheels at both ends of the tank car shall be blocked.

  • (3) Tank cars shall be disconnected from pipelines immediately after the completion of loading or unloading operations.

  • (4) Loading or unloading operations shall be carried out only during the hours of daylight unless fixed permanent electric lighting is provided in accordance with section 66.

 Except as provided in the schedule, the direct transfer of anhydrous ammonia between tank cars and tank trucks or drums on carrier’s right-of-way is prohibited.

 The loading or unloading of tank cars located on a carrier’s track are subject to the following conditions:

  • (a) except as provided in paragraph (d), tank car liquid discharge connections shall be equipped with excess flow valves;

  • (b) except as provided in section 61, lading shall be piped directly to permanent storage tanks of sufficient capacity to receive the entire contents of the tank car. The tanks and all of the facilities associated with them shall be in accordance with all applicable provisions of these Regulations;

  • (c) when the carrier’s track is a team track, it is recommended that where practicable, the tank car be protected during loading or unloading by a locked derail located at least one car length from the tank car on the connected end or ends of the team track; and

  • (d) tank cars of the I.C.C. 106A type may be loaded or unloaded on carrier’s track if written permission is obtained from the carrier concerned, and equipment is provided for the safe unloading or loading of the unit tanks, but such tanks shall not be stored on carrier’s property except as provided in these Regulations.

 Loading or unloading tracks which cross street railway tracks or show evidence of stray electric currents shall be insulated from the rest of the track at the loading or unloading site in accordance with the Electric Sparks Prevention Regulations. Loading or unloading tracks equipped for electrical operation shall comply with those Regulations.


 The area within 25 feet of a storage tank exceeding 200 Imperial gallons, a loading or unloading rack, pump, building, etc. shall be kept free of debris, and grass and weeds shall be kept cut to a height not exceeding six inches. The general housekeeping and maintenance of buildings, tanks, etc. shall be of the highest standard.

 Defective piping, valves, or fittings shall be repaired immediately.

  •  (1) All electrical equipment, fixtures, switches, and wiring inside buildings where anhydrous ammonia is stored or handled shall conform to the requirements of the latest edition of the Canadian Electrical Code for Class I, Division II hazardous locations and any local or provincial requirements of a higher standard.

  • (2) Electrical installations in other locations within 25 feet of any anhydrous ammonia storage tank, equipment, or loading or unloading point shall conform to the requirements of the latest edition of the Canadian Electrical Code for corrosive atmospheres (Category 2).

  •  (1) All uninsulated storage containers with a water capacity exceeding 100 Imperial gallons which are installed out-of-doors shall be painted with a white heat reflective coating, preferably an enamel or self-cleaning paint.

  • (2) The words “CAUTION — AMMONIA” in letters not less than six inches high shall be painted on each outdoor tank with a water capacity exceeding 2,000 Imperial gallons.

  •  (1) Except for the frame, pumphouses, compressor houses, or buildings in which anhydrous ammonia is handled shall be constructed of noncombustible or fire-resistant materials.

  • (2) All enclosures where anhydrous ammonia is handled shall be cross-ventilated with permanently open louvers at the ceiling level.

  • (3) Containers of flammable liquids or gases shall not be stored in a room occupied by anhydrous ammonia equipment.

  • (4) Buildings shall be maintained in a clean and tidy condition.

 Smoking and the use of portable open flame lights or equipment shall be prohibited except in certain isolated and clearly-designated areas. Signs to this effect shall be posted at the plant entrances and at the loading and unloading sites. (See section 72 for restrictions applying to welding.)

 All anhydrous ammonia installations are subject to inspection at any time by any duly-authorized officer of the Commission.

 The owning or operating company shall report by wire to the railway company and the Director of Operation, Canadian Transport Commission, Ottawa, every fire resulting in damage to the installation, explosion, or major pipeline or tank failure occurring on the installation, and shall submit a detailed report by mail.

 Welding shall not be permitted within 100 feet of a loading or unloading site while loading or unloading operations are in progress. At other times, welding shall only be allowed when carried out under close supervision and in accordance with the provisions of Canadian Standards Association pamphlet W-117.

  •  (1) Each storage area with a water capacity exceeding 2,000 Imperial gallons should be protected by at least one standard fire hydrant so located that a 2½-inch hose stream may be used for controlling a fire on the site or for cooling a tank in case of adjacent fires. Consultation with the local fire authority is recommended.

  • (2) Fire extinguishers suitable for small fires shall be available on installations with a storage capacity exceeding 2,000 Imperial gallons. At least one fire extinguisher shall be kept on the outside premises.

 The principal hazards associated with the handling of anhydrous ammonia are as follows:

  • (a) mixtures of air and anhydrous ammonia consisting of 16 to 25 per cent by volume of anhydrous ammonia are flammable and may ignite at a temperature as low as 1204°F in the presence of iron. For outdoor installations, this condition is not likely to be obtained except as a result of a tank or pipeline rupture. However, serious fires and explosions have occurred in which anhydrous ammonia was a contributing factor. Anhydrous ammonia becomes slightly unstable at 840-930°F and dissociates into hydrogen and nitrogen. The presence of small quantities of oil or other combustible material in anhydrous ammonia will increase the fire hazard;

  • (b) 100 p.p.m. is the maximum average atmospheric concentration of ammonia to which workers may be repeatedly exposed without adverse effect on their health. Exposure to concentrations of 250 p.p.m. for 30 minutes is considered dangerous and an exposure of 30 minutes’ duration to concentrations of 5,000 p.p.m. is considered to be fatal. Industrial gas masks of a type approved for use in ammonia atmospheres should be located in a convenient place. Approximately 400 p.p.m. will cause immediate throat irritation and 700 p.p.m. will cause immediate eye irritation; and

  • (c) in addition to the above-mentioned hazards, anhydrous ammonia is shipped and stored under pressure and those general safety precautions prescribed for the handling of compressed gases should be observed.

 Safety equipment, as prescribed in the current edition of Agricultural Ammonia Institute pamphlet, Standards for the Storage and Handling of Anhydrous Ammonia should be provided at all bulk storage installations.

 For further details, the following publications are suggested:

  • (a) Standards for the Storage and Handling of Anhydrous Ammonia, by the Agricultural Ammonia Institute of Memphis, Tennessee;

  • (b) Anhydrous Ammonia Pamphlet G-2, by the Compressed Gas Association, Inc., 500 Fifth Ave., New York 36, New York;

  • (c) Chemical Safety Data Sheet SD-8, by the Manufacturing Chemists’ Association, Inc., 1625 Eye Street N.W., Washington 6, D.C.;

  • (d) Compressed Gas Association pamphlet Safety Relief Device Standards for Compressed Gas Storage Containers, published by the Compressed Gas Association, Inc., 500 Fifth Ave., New York 36, New York; and

  • (e) Liquefied Petroleum Gas pamphlets No. 58 and No. 59 by the National Fire Protection Association, 60 Batterymarch Street, Boston 10, Massachusetts.


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