51. All piping inside buildings where anhydrous ammonia is stored or handled shall be grounded to prevent the build-up of static electricity. The resistance to ground shall be as low as possible and preferably not more than six ohms.

• 52. (1) All piping, valves and fittings shall be inspected and tested after assembly and prior to commencing operations for the first time and be proven gastight at a pressure not less than the working pressure of the tank, pump or device to which they are connected, or at 150 psig if this is a higher pressure.

• (2) The results of the piping inspection and test shall be reported to the Commission.

• 53. (1) If housed, pumps or compressors driven by internal combustion engines or non-explosion proof motors shall comply with subsections (3) to (6).

• (2) The pump or compressor should be separated from the engine or motor by a fireproof and vapour-proof wall.

• (3) Except for the frame, the building shall be constructed of noncombustible or fire-resistant materials.

• (4) Engine exhausts shall terminate outside the building.

• (5) The building shall be cross-ventilated near the ceiling level.

• (6) The entire system shall be maintained in good operating condition at all times.

• 54. (1) Each unrefrigerated tank shall be equipped with one or more safety relief valves of the spring loaded type or an equivalent type which have been approved for the intended service by the Boiler and Pressure Vessel Committee of A.S.M.E., or the Compressed Gas Association, Inc., or Underwriters’ Laboratories.

• (2) The valves referred to in subsection (1) shall be of a size that will ensure a rate of discharge not less than that specified in the current edition of Agricultural Ammonia Institute pamphlet, Standards for the Storage and Handling of Anhydrous Ammonia.

• (3) The rate of discharge prescribed in subsection (2) shall be obtained before the pressure is in excess of 120 per cent of the maximum permitted start to discharge pressure setting of the device.

• (4) The rate of discharge for relief valves on refrigerated tanks shall be in accordance with the current edition of Agricultural Ammonia Institute pamphlet, Standards for the Storage and Handling of Anhydrous Ammonia.

• (5) Safety relief valves on unrefrigerated tanks shall be set to start to discharge at pressures as prescribed in the current edition of Agricultural Ammonia Institute pamphlet, Standards for the Storage and Handling of Anhydrous Ammonia.

• (6) Relief valves on refrigerated containers shall be set to discharge at a pressure not in excess of the design working pressure of the container.

• (7) Safety relief valves shall be installed in a manner that will ensure that the full relief requirements are always satisfied.

• 55. (1) All storage tank relief devices shall be located on the storage tank and shall have direct communication with the vapour space of the tank.

• (2) If the design of the relief system is such that liquid can collect on the discharge side of the disc, the valve shall be equipped with a suitable drain.

• (3) Tank safety relief valves shall be vented vertically to the outside atmosphere at a safe location and at least seven feet above the tank; except that for a tank of 2,000 Imperial gallons capacity or less and not provided with a ladder or other means of access to the top, the top of the vent shall not be less than seven feet above ground level.

• (4) The end of the vent pipe shall be fitted with a loose rain cap that will not freeze in place.

• (5) Safety relief devices shall be so arranged that the possibility of tampering will be minimized.

• (6) Return bends and restrictive piping are not permitted in relief valve piping.

• (7) External pressure settings or adjustments shall be sealed.