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Interpretation Response #02-0199

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date: 10-22-2002
Company Name: Shell Chemical LR    Individual Name: DavidJ. Mashinski
Location state: LA    Country: US

View the Interpretation Document

Response text:

Oct 22, 2002

David J. Mashinski                 Reference No. 02-0199
HSE Advisor
Shell Chemical LR
910 Louisiana Street
Houston, Texas 77002-2463

Dear Mr. Mashinski:

This is in response to your July 17, 2002 letter concerning attendance requirements for rail car unloading under the Hazardous Materials Regulation (HMR; 49 CFR parts 171-180) Specifically, you ask if the attendance requirements apply to a tank car undergoing a steaming process that is not attached to an unloading process. You further state that the vapors are being vented through a valve on the car.

On February 18, 2000, we provided you with a clarification of the rail car attendance requirements as they apply to a steaming process during which vapors are vented through a valve that is connected via closed pipe to a permitted air pollution control device (Ref. No. 99-0301). In addition, on November 15, 20Ol, we issued a letter of clarification on Koch Materials Company (Ref. No.01-0269) concerning attendance requirements for a steaming process that is conducted with the manway slightly open to relieve any potential pressure. Both letters stated that attendance is not required when a tank car is connected to a steaming device that is not interconnected with or part of the unloading process of if the steaming process is conducted with all valves and manways closed. This statement apparently has resulted in some confusion as to the applicability of the attendance requirements to certain steaming operations.

We are withdrawing letter Ref. No. 01-0269, which we issued on November 15, 2001.  In that letter, we erroneously affirmed an interpretation that would allow a tank car, undergoing a steaming process before unloading, to have an open manway without being attended.  We apologize for the error and subsequent confusion this may have caused.

The attendance requirements set forth in § 174.67(i) apply to a steaming operation that is connected to or part of the unloading process.  Further, the attendance requirements apply when manways or valves are open to relieve pressure, either to the atmosphere or a pollution control device, during heating of a material in preparation for unloading, even if the steaming process is not connected to or part of the unloading process itself.  Thus, the steaming process you describe is subject to the attendance requirements in § 174.67(i).

I hope this information is helpful.  If you have further questions, please do not hesitate to contact this office.


Edward Mazzullo
Director, Office of Hazardous Materials Standards,


Regulation Sections

Section Subject
§ 174.67 Tank car unloading