Safety Advisory 2009-02
FRA is issuing Safety Advisory 2009-02 to ensure that tank cars with defective or inoperable bottom outlet valves are not loaded with hazardous materials and offered for transportation, or in the event that a bottom outlet valve becomes inoperable en route, adequate unloading procedures are followed to prevent any unintended release of the car's contents. This safety advisory recommends specific loading and unloading procedures for hazardous materials tank cars equipped with bottom outlet valves, as well as the inspection, and as necessary, the repair of these valves.
Table of Contents
- 1. Loading a Railroad Tank Car Equipped With a Bottom Outlet Valve or Valves
- 2. Unloading a Railroad Tank Car Equipped With a Bottom Outlet Valve or Valves
- 3. Cleaning and Purging of a Railroad Tank Car Equipped With Bottom Outlet Valves
- Sources for Additional Information
For further information contact: ↑
Albert R. Taber or Erich P. Rudolph, Railroad Safety Specialists, Hazardous Materials Division, FRA Office of Safety Assurance and Compliance, 1200 New Jersey Avenue, SE., Washington, DC 20590 (telephone: (202) 493-6254, e-mail:Albert.Taber@dot.gov; or telephone (202) 493-6248, e-mail:Erich.Rudolph@dot.gov).
Supplementary information: ↑
By way of the one-time movement approval process (Title 49 Code of Federal Regulations (CFR) 174.50), FRA has documented approximately 390 service equipment failures of bottom outlet valves since 2004. One hundred and eight of these failures occurred in calendar year 2008 alone, and to date in 2009, approximately 110 failures have already occurred. FRA believes that these documented failures do not reflect the entire population of bottom outlet failures that occur each year, as many may go unreported.
As exemplified by documented incidents of bottom outlet failures, a defective or inoperable bottom outlet valve may lead to the unintended release of a tank car's contents during the unloading process. As an example, on October 28, 2004, at Techsol Chemical Company, in Huntington, WV, more than 22,000 gallons of a Class 3 hazardous material was released during the unloading of a tank car equipped with a bottom outlet valve. The release was determined to be the result of a bottom outlet valve clogged with sludge, and an unloading procedure that failed to detect the inoperative valve. On May 31, 2008, approximately 170,000 lbs of a Class 9 elevated temperature material was released during the unloading of a tank car equipped with a bottom outlet valve. The elevated temperature material had been heated to approximately 280 °F for unloading and although the individual unloading the car reportedly observed the bottom outlet valve handle secured and in the closed position, as that individual removed the bottom outlet cap, hot steamed resin was released from the bottom outlet, splashing the unloader. The resin released at a rate of approximately 160 gallons per minute and the unloader suffered first- and second-degree burns from contact with the material. The release was determined to be the result of a bent bottom outlet valve handle, which allowed the internal valve to be in the open position, and unloading procedures that failed to detect the inoperative valve. More recently, on May 13, 2009, approximately 23,500 gallons of hot asphalt, a Class 9 hazardous material, was released during the unloading of a tank car equipped with a bottom outlet valve. In this case, because the valve operating handle was improperly applied to the valve assembly, the handle appeared to be in the closed position, but the internal valve was actually in the open position. Accordingly, this release was determined to be the result of the improperly applied valve handle, and loading and unloading procedures that failed to detect the improperly assembled valve.
FRA believes that the occurrence of bottom outlet valve failures could be significantly reduced by (1) ensuring that certain procedures are followed during the tank car loading and unloading process, and (2) ensuring that a proper preliminary examination of the valve assembly is performed after a tank car is cleaned and purged, and before the car is loaded and offered for transportation.
FRA's recommendations in this safety advisory take into consideration the typical operational steps involved in loading/unloading tank cars equipped with bottom outlet valves, regardless of whether the valve is “top-operated” or controlled by a valve-mounted handle (“bottom-operated”). Generally, the bottom outlet cap or plug should not be removed from a tank car's bottom outlet discharge nozzle until it is ascertained that the bottom outlet valve is actually closed and functioning properly. In accordance with Appendix E of the Association of American Railroads' (AAR) Tank Car Committee Tank Car Manual,  tank car bottom outlet caps and plugs are designed to provide tell-tale warnings upon loosening if a bottom outlet valve is not functioning properly. Accordingly, the design of bottom outlet discharge nozzles and closures allows any product that has accumulated between the bottom outlet operating valves and the bottom outlet closure cap or plug (i.e., in the outlet chamber) to drain in a safe and controlled manner. Once it is determined, by using the relationship of the handle to the valve as an indicator, that the bottom outlet valve is in the closed position, a person unloading a tank car should loosen the bottom outlet cap a few turns, leaving sufficient threads engaged, and allowing the passage of sufficient time to permit the controlled seepage of any liquid accumulated in the outlet chamber. If a tank car is equipped with an auxiliaryvalve below the primary bottom outlet valve, that auxiliary valve should be in the open position, with its cap/plug removed, allowing an unloader to determine whether the primary valve is functioning properly. Once this accumulated product has drained out around the closure, the leakage should stop. This is an indication that the bottom outlet valve is functioning properly and that it is safe for the unloader to proceed with removing the bottom outlet cap or plug (a properly functioning bottom outlet valve in the closed position will contain the contents of the car on its own).
If, however, leakage continues upon the loosening of a bottom outlet cap or plug, or there is an excessive amount of product drainage, this is an indication that the primary bottom outlet valve is not functioning properly (e.g., the valve may be defective, debris may be clogging the valve seat area and/or assembly components, or the valve is otherwise failing to function properly). Accordingly, the bottom outlet valve cap or plug should not be completely removed. Instead, the cap or plug should be secured and the tank should be unloaded from the fittings on top of the car. Unless FRA has granted a movement approval pursuant to 49 CFR 174.50, tank cars identified with bottom outlet valves not functioning properly cannot be offered into transportation in compliance with the Hazardous Materials Regulations (HMR) (49 CFR Parts 171-180).
The proper functioning of the bottom outlet valve is critical during the unloading of hazardous materials tank cars. Prior to June 1, 2005, the tank car unloading requirements of Part 174 of the HMR applied to all hazardous material tank car unloading operations. These requirements were set forth in Section 174.67 of the HMR and included certain procedural requirements. Specifically, Section 174.67(g) required that during tank car unloading operations, if leakage was apparent upon starting the removal of a tank's bottom outlet cap, the cap may not be entirely unscrewed. Instead, Section 174.67(g) required that “[s]ufficient threads * * * be left engaged and sufficient time allowed to permit controlled escape of any accumulation of liquid in the outlet chamber.” Only if the leakage stopped or the rate of leakage diminished materially, could the bottom outlet cap be entirely removed in accordance with Section 174.67(g). That section further provided that “[i]f the initial rate of leakage continues, further efforts must be made to seat the outlet valve * * *. If this fails, the [bottom outlet cap] must be screwed up tight and the tank must be unloaded through the dome.”
On April 15, 2005, the Pipeline and Hazardous Materials Safety Administration (PHMSA) published a final rule, which modified the HMR's applicability to certain tank car unloading processes. See 72 FR 20018. The end result of this final rule was that the requirements of Section 174.67 related to the protection of train and engine crews operating within a shipper or consignee facility were consolidated in Part 173 of the HMR, and the remaining procedural requirements of Section 174.67, including paragraph (g), became applicable only to transloading operations (i.e., the transfer of a hazardous material from one packaging to another for the purpose of continuing transportation in commerce). Although the HMR currently only explicitly requires that the procedures of Section 174.67(g) be followed during transloading operations, FRA recommends that persons responsible for unloading hazardous materials tank cars equipped with bottom outlet valves follow these procedures in all tank car unloading operations in order to detect an inoperable or defective bottom outlet valve, which could lead to an unintended release of a car's contents during the unloading process.
The proper functioning of the bottom outlet valve is also critical during the loading of railroad hazardous materials tank cars. Prior to July 1, 1996, the HMR specifically required that “[t]anks with bottom discharge outlets must have their outlet caps off, or outlet cap plugs open, during the entire time tanks are being loaded.” See 49 CFR 173.31(b) (1994). That same section of the HMR also prohibited tanks with bottom outlet valves which, after loading, permitted more than a dropping of the liquid contents of the tank with the outlet caps off, or the outlet cap plugs open, from being offered for transportation until proper repairs had been made. On September 21, 1995, the Research and Special Program Administration (RSPA), now known as PHMSA, published a final rule, developed jointly with FRA, that “revised and reorganized for clarity” 49 CFR 173.31, which addressed the qualification, maintenance, and use of tank cars. See 68 FR 49048, 49067 (effective July 1, 1996). RSPA's stated intent in revising and reorganizing 49 CFR 173.31 was to “align the inspection requirements in * * * 173.31(b) with the design and operations requirements” generally applicable for packagings and packages in 49 CFR 173.24. Id. at 49064. RSPA intended the revision to “clarify [the inspection requirements'] full intent, foster compliance with safety standards, and improve hazardous materials transportation safety.”Id. The rule was not intended to substantively modify the previous requirements of 49 CFR 173.31(b).
Although explicit language no longer appears in the HMR requiring bottom outlet caps to be off or outlet cap plugs to be open during the loading process, or prohibiting loaded tank cars, with more than a dropping of liquid with their outlet caps off or outlet cap plugs open, from being offered for transportation until repairs have been made, the requirements of 49 CFR 173.24 remain the same. Specifically, 49 CFR 173.24 requires that packages used for the transportation of hazardous materials be “designed, constructed, maintained, filled, * * * contents so limited, and closed, so that under conditions normally incident to transportation * * * there will be no identifiable release of hazardous materials to the environment.” Accordingly, FRA recommends that persons responsible for loading tank cars equipped with bottom outlet valves follow the inspection and operational procedures recommended below in order to detect an inoperable or defective bottom outlet valve, which could lead to an unintended release of the car's contents during transportation or during the process of loading or unloading the car.
FRA reminds those responsible for loading and unloading railroad tank cars that the United States Department of Labor Occupational Safety and Health Administration's rule regarding process safety management of highly hazardous chemicals (29 CFR 1910.119), the U.S. Environmental Protection Agency's risk management plan regulations (40 CFR Part 68), and other standards and rules of these agencies may also apply to tank car loading and unloading operations in certain circumstances.
Recommended Action: Based on the necessity to reduce the number and severity of incidences due to bottom outlet valve failures and to enhance the public's confidence in the safety of hazardous materials transportation by rail, FRA makes the following recommendations:
1. Loading a Railroad Tank Car Equipped With a Bottom Outlet Valve or Valves ↑
Persons responsible for loading a tank car equipped with a bottom outlet valve or valves should:
2. operate the bottom-outlet valve handle(s) to verify proper operation. Once proper operation has beenverified, the valve(s) should be closed and secured, as appropriate.
3. ensure that the tank has its bottom outlet cap off, or outlet plug open, during the entire time the tank is being loaded.
4. ensure that bottom outlet auxiliary valve(s) (if a tank car is so equipped) is open during the entire time the tank is being loaded.
5. ensure that after loading, a tank with a bottom outlet valve that permits more than a dropping of the liquid contents of the car with the outlet cap off, or the outlet cap plug open, is not offered for transportation until proper repairs have been made.
2. Unloading a Railroad Tank Car Equipped With a Bottom Outlet Valve or Valves ↑
Persons responsible for unloading a tank car equipped with a bottom outlet valve or valves should:
6. confirm that the bottom outlet valve is closed before loosening the bottom outlet cap or plug. If it cannot be confirmed that the bottom outlet valve is closed, the valve cap or plug should not be removed. Instead, the tank car should be unloaded through the fittings on top of the car, and corrective action taken to repair the bottom outlet valve.
7. ensure that during the unloading process, if leakage shows upon starting the removal of the bottom outlet cap or plug, the cap or plug should not be entirely unscrewed. Sufficient threads should be left engaged and sufficient time allowed to permit controlled escape of any accumulation of liquid in the outlet chamber. If the leakage stops, the cap or plug may be entirely removed. If leakage continues, further efforts must be made to seat the outlet valve. If this fails, the cap must be screwed up tight (or the plug secured), the tank must be unloaded through the fittings on top of the car, and corrective action must be taken to repair the bottom outlet valve.
3. Cleaning and Purging of a Railroad Tank Car Equipped With Bottom Outlet Valves ↑
Persons responsible for the cleaning and purging of tank cars equipped with bottom outlet valves, should ensure that after the cleaning and purging process is complete, the bottom outlet valves and valve assemblies are examined for debris or obstructions prior to releasing the cars for further transportation.
Sources for Additional Information ↑
Questions concerning the operation and maintenance of bottom outlet valves should be referred to the car owner for special instructions to ensure continued reliability of the bottom outlet valve. For specific literature on loading/unloading tank cars, refer to the AAR's Pamphlet No. 34 titled, “Recommended Methods for the Safe Loading and Unloading of Non-Pressure Tank Cars.”
For purposes of this safety advisory, FRA seeks cooperation from the entities who are responsible for determining that tank cars are in proper condition and safe for transportation. FRA will continue to monitor the status of tank cars equipped with bottom outlet valves in hazardous materials transportation and will take any necessary regulatory or enforcement action to ensure the highest level of safety on the Nation's railroads.Issued in Washington, DC, on October 9, 2009. Jo Strang, Associate Administrator for Railroad Safety/Chief Safety Officer.