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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Interpretation Response #02-0071

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

Interpretation Response Details

Response Publish Date:

Company Name:

Individual Name:

Location State: MO Country: US

View the Interpretation Document

Response text:

Oct 22, 2002

Ms. Sarah R. Maguffee                     Reference No. 02-0071
Husch & Eppenberger, LLC
235 East High Street
P.O. Box 1251
Jefferson City, MO 65102-1251

Dear Ms. Maguffee:

This responds to your February 27, 2002 letter concerning attendance requirements for rail car unloading under the Hazardous Materials Regulations (HMR; 149,CFR Parts 171-180).  Specifically, you ask if the attendance requirements apply to a tank car undergoing a teaming process that is not attached to an unloading process.  You further state that the man way opening is slightly ajar during the steaming process.  You enclosed a previous letter of clarification (Ref. No. 99-0301; dated February 18, 2000) that you suggest permits you to perform an unattended steaming operation with the man way open, provided the steaming process is not connected to or part of the unloading process.

The February 18, 2000 letter addresses 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. In addition, on November 15, 2001, we issued a letter of clarification to Koch Materials Company (Ref No. 01-0269) concerning attendance requirements for a steaming process that is conducted with the man way 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 or 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 with an interpretation that would allow a tank car, undergoing a steaming process before unloading, to have an open man way 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