Shell Chemical Company — Hazardous Materials Safety Interpretation

Page 1U.S. Department of Transportation Nashington, D.C. 20590 1C0 Seventh Street, SW esearch anc FEB 1 8 2000 Mr. David J. Mashinski Ref. No. 99-0301 Shell Chemical Company Transportation Safety and Regulations 910 Louisiana Street Houston, Texas 77002-2463 Dear Mr. Mashinski: This responds to your letter of October 26, 1999, requesting cars under the Hazardous Materials Regulations (HMR; 49 CFR Parts clarification of the attendance requirements for unloading tank during which vapors are vented through a valve that is connected Your letter describes a tank car steaming process ask whether this process must be attended in accordance with via closed pipe to a permitted air pollution control device. You $ 174.67 of the HMR. The answer is yes. During a tank car steaming process that is attended. conducted with an open valve or manway, the tank car must be device that is not interconnected with or part of the unloading However, when a tank car is connected to a steaming process or if the steaming process is conducted with all valves and manways closed, attendance is not required. I hope this information is helpful. If you have further questions, please do not hesitate to contact this office. Sincerely, Thorn Thomas G. Allan Office Senior Transportation Regulations Specialist of Hazardous Materials Standards 17467 990301 -#

Page 2Shell Chemicals Gorsky $174.67 October 26, 1999 99-0301 Office of Hazardous Materials Standards - DHM-10 400 T Street, SW U.S. Department Of Transportation Washington, D.C. 20590-0001 Dear Mr. Mazzullo, Shell Chemical Company seeks clarification of the scope of "unloading" in relation to tank cars, specifically the attendance requirement per 49CFR 174.67. A tank car of a product with the proper shipping name of Flammable Liquid, Corrosive, NOS, and a packing group of Il is being steamed for approximately 10 hours before the product is unloaded. During the steaming process the vapors are being vented through a valve in the car which is connected via a closed pipe to a permitted air pollution control device (flare). We would appreciate your clarification in regards to the steaming process and whether this: process is considered part of "unloading" in the circumstance stated above. Our thanks in advance for your prompt consideration of this request. I may be contacted at (713) 241-6436. Shell Chemical Company 910 Louisiana Street Houston, Texas 77002-2463 Sincerely, Saved A Masher David J. Mashinski Transportation Safety & Regulations ONE SHELL PLAZA P.O. BOX 2463 HOUSTON. TX 77252-2463 SHELL CHEMICAL COMPANY -#