PART IIIStorage Tanks (continued)
28 Each tank with a water capacity exceeding 5,000 Imperial gallons should be equipped with a suitable thermometer unless some other provision is made for determining the liquid temperature.
29 The below-ground installation of anhydrous ammonia tanks on the carrier’s right-of-way is prohibited.
30 (1) Except as provided in subsection (7), storage tanks shall be securely installed on solid foundations of steel or reinforced concrete with reinforced concrete footings extending below the frost line or resting on bedrock.
(2) Except as provided in subsection (6), steel foundations shall be fire-proofed with a material having a fire resistance rating of not less than two hours.
(3) Foundations shall be of sufficient width and thickness to adequately support the tank and its contents.
(4) Provision shall be made for the thermal expansion and contraction of a tank.
(5) Only two saddles shall be used for horizontal tanks.
(6) Steel saddles which are welded to a tank need not be fire-proofed if the tank capacity does not exceed 500 Imperial gallons, or if the over-all height of the saddle does not exceed 18 inches.
(7) Footings for tanks with a water capacity less than 500 Imperial gallons need not be installed below frost line if adequate provision is made to protect the piping against the effects of settling.
(2) Storage tanks shall not be installed in outdoor locations where the natural dispersal of fumes would be seriously restricted.
32 (1) The filling density of above-ground unrefrigerated tanks shall not exceed 56 per cent for uninsulated tanks and 57 per cent for insulated tanks; for volume filling at various liquid temperatures, refer to chart of figure 23, Pamphlet G-2 of Compressed Gas Association, Inc.
(2) The maximum amount of anhydrous ammonia that may be charged into a refrigerated storage container shall be that which theoretically would make the container liquid-full at a pressure equal to 120 per cent of the design pressure of the container under equilibrium conditions of temperature and pressure.
33 (1) Unless filling is controlled by weighing, tanks shall be equipped with a fixed tube liquid level, a rotary tube, an adjustable slip tube gauge, or other gauging device that will ensure that the maximum permitted filling density is not exceeded. If the gauging device is a float type or pressure differential type, the tank shall also be provided with a fixed tube, rotary tube, or adjustable slip tube gauge.
(2) Gauge glasses of the columnar type shall be equipped with shut-off valves having metallic hand wheels, excess flow valves, extra heavy glass adequately protected by a metal housing applied by the manufacturer and shall be protected from the direct rays of the sun.
PART IVPiping and Transfer Equipment
34 Pumps and compressors used for transferring anhydrous ammonia shall be of a type suitable for anhydrous ammonia service, shall be designed for not less than 250 psig working pressure, and shall be so recommended and permanently marked or labelled by the manufacturer.
35 Piping at pumps and compressors shall be so arranged as to ensure the safe operation of this equipment.
36 Refrigeration load and equipment for refrigerated storage systems shall be in accordance with the current edition of Agricultural Ammonia Institute pamphlet, Standards for the Storage and Handling of Anhydrous Ammonia.
(2) The hose, as assembled for use, shall be tested for leaks at not less than twice the maximum working pressure before being put into service and should be tested at least annually thereafter at not less than 1½ times the maximum working pressure.
(3) The hose shall be permanently and clearly marked or labelled “For Anhydrous Ammonia” or “NH3”, or “A.A.”, together with the maximum working pressure, manufacturer’s name or symbol and year of manufacture.
(4) Hose couplings shall be of steel.
(5) Hose materials shall be resistant to the action of anhydrous ammonia under the service conditions to which they will be subjected.
(6) Hose and hose connections located on the low pressure side of flow control or pressure reducing valves or devices, discharging to atmospheric pressure, shall be designed for a minimum working pressure of 60 psig.
(7) Where hose is to be used for transferring liquid, wet hose is recommended and the hose shall be equipped with a shut-off valve on the discharge end and provision shall be made to prevent excessive hydrostatic pressure on the hose.
(8) The use of hose is prohibited for interconnecting stationary containers.
(2) Brazed joints are prohibited.
(3) Unless the dryness of the ammonia can be assured, copper; copper, silver or zinc alloys, including brass or bronze; or galvanized pipe, valves or fittings shall not be used.
(4) The use of cast iron pipe, valves or fittings in anhydrous ammonia service is prohibited.
(5) Anhydrous ammonia shall not be allowed to come in contact with mercury in manometers and other equipment.
(6) Joint compounds and pipe dopes shall be suitable for ammonia service.
(7) Welding shall only be done by a qualified welder recognized as such by the Boiler and Pressure Vessel Inspection Branch of the provincial government concerned.
39 All storage tank connections, except those for safety relief valves or gauges, shall be labelled to indicate whether they communicate with the vapour or liquid phase during normal operations.
40 All storage tank connections, except those for gauges, safety relief valves or plugged openings, shall be provided with shut-off valves located as close to the tank as possible.
41 (1) All shut-off valves, throttling valves, gauges, and accessory equipment shall be of a type suitable for anhydrous ammonia service and shall be designed for not less than the maximum working pressure to which they may be subjected, except that the rated working pressure of valves, etc., subject to container pressure shall not be less than 250 psig.
(2) All valves, gauges, fittings, and accessory equipment mentioned in subsection (1) shall be permanently marked or labelled with their maximum working pressure and the letters “A.A.” or “NH3” to indicate their suitability for anhydrous ammonia service; e.g., “250 — A.A.”.
42 (1) Except as provided in subsection (4), all openings in unrefrigerated containers, except those for safety relief valves and those connections protected by an opening not larger than a No. 54 drill size (0.0550 inch), shall be equipped with excess flow valves or other suitable automatic valve or device which will automatically prevent loss of the tank contents in the event of a connection or line failure.
(2) Connections on refrigerated containers shall be protected with excess flow valves or other devices as prescribed in the current edition of Agricultural Ammonia Institute pamphlet, Standards for the Storage and Handling of Anhydrous Ammonia.
(3) Excess flow valves shall be designed with a bypass not to exceed a No. 60 drill size (0.0400 inch) opening to allow equalization of pressures.
(4) An excess flow valve or other automatic device as prescribed in subsection (1) is not required for withdrawal connections of unrefrigerated tanks with a water capacity not exceeding 1,500 Imperial gallons, if the connection is protected by a controlling orifice not exceeding 5/16 inch diameter for vapour withdrawal and 1/8 inch diameter for liquid withdrawal, a manually operated shut-off valve, and a pressure-reducing regulator, all of which shall be assembled to the connection as prescribed in 2.2(d), Division II of the 1958 edition of National Fire Protection Association pamphlet No. 58.
(5) Excess flow valves shall be permanently marked or labelled by the manufacturer with their maximum working pressure, rated capacity and the letters “A.A.” or “NH3” to indicate their suitability for use in anhydrous ammonia service.
(6) Excess flow valves or other automatic devices, as referred to in subsection (1), shall be installed in such a manner that rupture of the line or connection will not adversely affect the protective device.
(7) The connection or line housing an excess flow valve shall have a greater capacity than the rated capacity of the excess flow valve.
43 Portable engines, motors, pumps and compressors are not recommended, but if used, shall be securely mounted on a rigid base and every precaution taken to ensure that the installation is stable and well protected against possible physical damage.
- Date modified: