Rail Safety Advisory Letter – 15/13
Operating lever design for tank car bottom outlet valve
Place du Centre
200 Promenade du Portage
26 November 2013
Ms. Marie-France Dagenais (ASD)
Director General, Transportation of Dangerous Goods
330 Sparks Street
Dear Ms. Dagenais:
Operating Lever Design for Tank Car Bottom Outlet Valve
On 03 April 2013, Canadian Pacific Railway (CP) freight train 420-02 (the train) was proceeding eastward on the CP Heron Bay Subdivision. The train was equipped with 3 head-end locomotives and was hauling 111 cars (64 empties and 47 loads), 22 of which were loaded with dangerous goods (DG). The train weighed 8232 tons and was 8198 feet long. At about 0750 Eastern Daylight Time, while travelling at 45 mph, the train experienced an undesired emergency brake application and came to a stop near Bremner, Ontario (Mile 13.1). Subsequent inspection determined that 23 cars (19 loads and 4 empties) had derailed, 8 of which were DG tank cars loaded with petroleum crude oil (UN 1267) (TSB Occurrence No. R13T0060).
During the derailment, a number of the cars slid down an embankment and came to rest in various positions. As a result of the accident, DOT Class 111 non-pressure tank cars TILX 192186, TILX 198203 and PROX 76346 were leaking product. TILX 198203 and TILX 192186 released about 3,220 litres and 98,480 litres of petroleum crude oil respectively. PROX 76346 released about 18,190 litres of canola oil.
During site examination, it was determined that:
- TILX 198203 sustained impact damage to the top of the car which bent 1 of the manway hold-down bolts and resulted in minor leaks from the man-way cover. The protective housing for the loading/unloading arrangement had been torn off and the one-inch air/vapour valve fitting was sheared off and product leaked from the fitting (see Photo 1). The bottom outlet valve (BOV) and skid protection remained intact.
- TILX 192186 sustained impact damage to the top of the car and the protective housing for the loading/unloading arrangement was torn off. Both the one-inch air/vapour valve fitting and the two-inch liquid valve fitting sheared off which resulted in release of product (see Photo 2). The skid protection remained intact and the BOV nozzle and cap assembly had sheared off below the BOV as intended. However, the BOV operating lever was bent in the open position and deformed such that it could not be closed by the responders (see Photo 3). The open BOV became the primary source of product release.
- PROX 76346 sustained impact damage to the top of car and 1 of the manway hold-downs had been torn off creating an air leak (see Photo 4). The skid protection remained intact while the BOV nozzle and cap assembly had sheared off below the BOV as intended. However, the BOV operating lever was bent which resulted in the BOV remaining partially open (see Photo 5). In this case, responders were able to close the BOV. However, while open and combined with the manway air leak, the BOV was the primary source of product release.
The Association of American Railroads (AAR) Manual of Standards and Recommended Practices (MSRP) specification M-1002 (M-1002) governs tank car construction. M-1002 Appendix E, section 10.1.2.8 specifies that bottom outlet valve handles, unless stowed separately, must either be designed to bend or break free on impact or be positioned so that the handles, in the closed position, are above the bottom surface of the skid protection. In this occurrence, the BOV operating levers of tank cars TILX 192186 and PROX 76346 met AAR design requirements yet failed to prevent product loss as both levers were bent and both BOVs opened and released substantial amounts of product.
Following the 2009 investigation into the Canadian National Railway (CN) freight train derailment in Cherry Valley, Illinois, the National Transportation Safety Board (NTSB) of the United States (US) determined that “existing standards and regulations for the protection of bottom outlet valves on tank cars do not address the valves’ operating mechanisms and therefore are insufficient to ensure that the valve remained closed during accidents.” The NTSB subsequently recommended to the US Pipeline and Hazardous Materials Safety Administration (PHMSA) that it:
“Require all bottom outlet valves used on newly manufactured and existing non-pressure tank cars are designed to remain closed during accidents in which the valve and operating handle are subject to impact forces. (R12-6). “
To date, the recommended changes have not been made and, as demonstrated in this accident, these types of releases continue to occur during derailments. With over 220,000 Class 111 tank cars currently in service in North America, many of which transport DGs, and their propensity for BOV operating lever failure resulting in product loss during accidents, Transport Canada may wish to review the BOV operating lever design requirements for Class 111 tank cars.
Original signed by Kirby Jang
Manager, Head Office & Central Regions
TSB Ottawa, ON
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