[Code of Federal Regulations] [Title 49, Volume 2] [Revised as of October 1, 2003] From the U.S. Government Printing Office via GPO Access [CITE: 49CFR174.67] [Page 643-645] TITLE 49--TRANSPORTATION CHAPTER I--RESEARCH AND SPECIAL PROGRAMS ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PART 174_CARRIAGE BY RAIL--Table of Contents Subpart C_General Handling and Loading Requirements Sec. 174.67 Tank car unloading. (a) In unloading tank cars, the following rules must be observed (see subpart F of this part for gases): (1) Unloading operations must be performed only by reliable persons properly instructed in unloading hazardous materials and made responsible for careful compliance with this part. (2) Brakes must be set and wheels blocked on all cars being unloaded. (3) Caution signs must be so placed on the track or cars to give necessary warning to persons approaching the cars from the open end of a siding and must be left up until after the cars are unloaded and disconnected from the discharge connection. The signs must be of metal or other comparable material, at least 30 cm (12 inches) high by 38 cm (15 inches) wide in size, and bear the words, ``STOP--Tank Car Connected'', or ``STOP--Men at Work'', the word ``STOP'' being in letters at least 10 cm (3.9 inches) high and the other words in letters at least 5 cm (2 inches) [[Page 644]] high. The letters must be white on a blue background. (4) Before a manhole cover or outlet valve cap is removed from a tank car, the car must be relieved of all interior pressure by cooling the tank with water or by venting the tank by raising the safety valve or opening the dome vent at short intervals. However, if venting to relieve pressure will cause a dangerous amount of vapor to collect outside the car, venting and unloading must be deferred until the pressure is reduced by allowing the car to stand overnight or otherwise cooling the contents. These precautions are not necessary when the car is equipped with a manhole cover which hinges inward or with an inner manhole cover which does not have to be removed to unload the car, and when pressure is relieved by piping vapor into a condenser or storage tank. (b) After the pressure is released, the seal must be broken and the manhole cover removed as follows: (1) Screw type. The cover must be loosened by placing a bar between the manhole cover lug and knob. After two complete turns, so that vent openings are exposed, the operation must be stopped, and if there is any sound of escaping vapor, the cover must be screwed down tightly and the interior pressure relieved as prescribed in paragraph (a)(4) of this section, before again attempting to remove the cover. (2) Hinged and bolted type. All nuts must be unscrewed one complete turn, after which same precautions as prescribed for screw type cover must be observed. (3) Interior type. All dirt and cinders must be carefully removed from around the cover before the yoke is unscrewed. (c) When the car is unloaded through a bottom outlet valve, the manhole cover must be adjusted as follows: (1) Screw type. The cover must be put in place, but not entirely screwed down, so that air may enter the tank through the vent holes in threaded flange of the cover. (2) Hinged and bolted type. A non-metallic block must be placed under one edge of the cover. (3) Interior type. The screw must be tightened up in the yoke so that the cover is brought up within one-half inch of the closed position. (d) When unloading through the bottom outlet of a car equipped with an interior manhole type cover, and in each case where unloading is done through the manhole (unless a special cover with a safety vent opening and a tight connection for the discharge outlet is used), the manhole must be protected by asbestos or metal covers against the entrance of sparks or other sources of ignition of vapor, or by being covered and surrounded with wet burlap or similar cloth material. The burlap or other cloth must be kept damp by the replacement or the application of water as needed. (e) Seals or other substances must not be thrown into the tank and the contents may not be spilled over the car or tank. (f) The valve rod handle or control in the dome must be operated several times to see that outlet valve in bottom of tank is on its seat before valve cap is removed. (g) The valve cap, or the reducer when a large outlet is to be used, must be removed with a suitable wrench after the set screws are loosened and a pail must be placed in position to catch any liquid that may be in the outlet chamber. If the valve cap or reducer does not unscrew easily, it may be tapped lightly with a mallet or wooden block in an upward direction. If leakage shows upon starting the removal, the cap or reducer may not be entirely unscrewed. Sufficient threads must be left engaged and sufficient time allowed to permit controlled escape of any accumulation of liquid in the outlet chamber. If the leakage stops or the rate of leakage diminishes materially, the cap or reducer may be entirely removed. If the initial rate of leakage continues, further efforts must be made to seat the outlet valve (see paragraph (f) of this section). If this fails, the cap or reducer must be screwed up tight and the tank must be unloaded through the dome. If upon removal of the outlet cap the outlet chamber is found to be blocked with frozen liquid or any other matter, the cap must be replaced immediately and a careful examination must be made to determine whether the outlet casting has been [[Page 645]] cracked. If the obstruction is not frozen liquid, the car must be unloaded through the dome. If the obstruction is frozen liquid and no crack has been found in the outlet casting, the car may, if circumstances require it, be unloaded from the bottom by removing the cap and attaching unloading connections immediately. Before opening the valve inside the tank car, steam must be applied to the outside of the outlet casting or wrap casting with burlap or other rags and hot water must be applied to melt the frozen liquid. (h) Unloading connections must be securely attached to unloading pipes on the dome or to the bottom discharge outlets before any discharge valves are opened. (i) Tank cars may not be allowed to stand with unloading connections attached after unloading is completed. Throughout the entire period of unloading, and while car is connected to unloading device, the car must be attended by the unloader. (j) If necessary to discontinue unloading a tank car for any reason, all unloading connections must be disconnected. All valves must first be tightly closed, and the closures of all other openings securely applied. (k) As soon as a tank car is completely unloaded, all valves must be made tight by the use of a bar, wrench or other suitable tool, the unloading connections must be removed and all other closures made tight. (l) Railroad defect cards may not be removed. (m) If oil or gasoline has been spilled on the ground around connections, it must be covered with fresh, dry sand or dirt. (n) All tools and implements used in connection with unloading must be kept free of oil, dirt, and grit. [Amdt. 174-26, 41 FR 16092, Apr. 15, 1976, as amended by Amdt. 174-26A, 41 FR 40685, Sept. 20, 1976; Amdt. 174-43, 48 FR 27699, June 16, 1983; Amdt. 174-68, 55 FR 52678, Dec. 21, 1990; 56 FR 66280, Dec. 20, 1991; Amdt. 174-81, 60 FR 49111, Sept. 21, 1995; Amdt. 174-83, 61 FR 28678, June 5, 1996]