For transloading operations, the following rules must be observed:

    (A) General requirements. 

          (1) Unloading operations must be performed by hazmat employees properly instructed in unloading 
                hazardous materials and made responsible for compliance with this section.
          
          (2) Each hazmat employee who is responsible for unloading must apply the handbrake and block at 
                least one wheel to prevent movement in any direction. If multiple tank cars are coupled together, 
                sufficient hand brakes must be set and wheels blocked to prevent movement in both directions.

          (3) Each hazmat employee who is responsible for unloading must secure access to the track to prevent 
               entry by other rail equipment, including motorized service vehicles. This requirement may be satisfied 
               by lining each switch providing access to the unloading area against movement and securing each 
               switch with an effective locking device, or by using derails, portable bumper blocks, or other equipment 
               that provides and equivalent level of safety.

          (4) Each hazmat employee who is responsible for unloading must display caution signs on the track or 
               on the tank cars to warn persons approaching the cars from the open end of the track and must be 
               left up until after all closures are secured and the cars are in proper condition for transportation. 
               The caution signs must be of metal or other durable material, rectangular, at 30.48 cm (12 inches) 
               high by 38.10 cm (15 inches) wide, and bear the word ``STOP.'' The word ``STOP'' must appear in 
               letters at least 10.16 cm (4 inches) high. The letters must be white on a blue background. 
               Additional words, such as ``Tank Car Connected'' or ``Crew at Work,'' may also appear in white 
               letters under the word ``STOP.''

          (5) The transloading facility operator must maintain written safety procedures (such as those it may 
               already be required to maintain pursuant to the Department of Labor's Occupational Safety and Health 
               Administration requirements in 29 CFR 1910.119 and 1910.120) in a location where they are 
               immediately available to hazmat employees responsible for the transloading operation.

          (6) 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 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) Throughout the entire period of unloading and while a tank car has unloading equipment attached, the 
         facility operator must assure that the tank car is:

         (1) Attended by a designated hazmat employee who is physically present and who has an unobstructed 
               view of the unloading operation; or

         (2) Monitored by a signaling system (e.g., video system, sensing equipment, or mechanical equipment) 
               that is observed by a designated hazmat employee located either in the immediate area of the tank 
               car or at a remote location within the facility, such as a control room. The signaling system must;

               (i) Provide a level of surveillance equivalent to that provided in subparagraph (1) of this paragraph 
                   (i); and;

               (ii) Provide immediate notification to a designated hazmat employee of any system malfunction or 
                    other emergency so that, if warranted, responsive actions may be initiated immediately.

    (J) Attendance is not required when piping is attached to a top outlet of a tank car, equipped with a protective 
         housing required under 
         Sec. 179.100-12 of this subchapter, for discharge of lading under the following conditions:

         (1) All valves are tightly closed.

         (2) The piping is not connected to hose or other unloading equipment and is fitted with a cap or plug of 
               appropriate material and construction.

         (3) The piping extends no more than 15.24 centimeters (6 inches) from the outer edge of the protective 
               housing.

    (K) In the absence of the unloader, a tank car may stand with unloading connections attached when no 
          product is being transferred under the following conditions:

         (1) The facility operator must designate a hazmat employee responsible for on-site monitoring of the 
               transfer facility. The designated hazmat employee must be made familiar with the nature and 
               properties of the product contained in the tank car; procedures to be followed in the event of an 
               emergency; and, in the event of an emergency, have the ability and authority to take responsible 
               actions.

         (2) When a signaling system is used in accordance with paragraph (i) of this section, the system must 
               be capable of alerting the designated hazmat employee in the event of an emergency and providing 
               immediate notification of any monitoring system malfunction. If the monitoring system does not have
               self-monitoring capability, the designated hazmat employee must check the monitoring system hourly 
               for proper operation.

          (3) The tank car and facility shutoff valves must be secured in the closed position.

          (4) Brakes must be set and wheels locked in accordance with paragraph (a)(2) of this section.

          (5) Access to the track must be secured in accordance with paragraph (a)(3) of this section.

    (L) 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.

    (M) Railroad defect cards may not be removed.

    (N) If oil or gasoline has been spilled on the ground around connections, it must be covered with fresh, 
         dry sand or dirt.

    (O) 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; 68 FR 61941, Oct. 30, 2003; 70 FR 20034, Apr. 15, 2005; 72 
FR 55693, Oct. 1, 2007]