56. 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.

• 57. (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.

58. 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.

• 59. (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.

• 60. (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.

61. 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.

62. 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.