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Letters of Interpretation

PHMSA has published several Frequently Asked Questions (FAQs) documents on programmatic topics. Please review these documents here at: https://www.phmsa.dot.gov/about-phmsa/phmsa-faqs.

Additionally, Office of Hazardous Materials Safety has published Hazardous Materials FAQs based on letters of interpretation on the following topics:

Office of Hazardous Materials Safety: For questions about transporting hazardous materials, needing clarifications of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180), or requesting a formal letter of interpretation, please go to the Hazardous Materials Information Center (HMIC) page for contact information (phone and email address). Pending interpretation letters that are under review by the Office of Hazardous Materials Safety can be found at Pending Hazardous Materials (Hazmat) Interpretations.  

Office of Pipeline Safety: A written regulatory interpretation, response to a question, or an opinion concerning a pipeline safety issue may be obtained by submitting a written request to the Office of Pipeline Safety (PHP–30), PHMSA, U.S. Department of Transportation, 1200 New Jersey Avenue SE., Washington, DC 20590–0001 or at the email address: pipeline_interp_submittal@dot.gov. In addition to email address, the requestor must include his or her return address and should also include a daytime telephone number. Requests should be submitted at least 120 days before the time the requestor needs a response. Note: electronic submission is provided as alternative to the 49 CFR Part 190.11(b) mail-in requirement.

Interpretation letters under review are available at the Office of Pipeline Safety’s Interpretation Review page. To submit comments on an interpretation under review, proceed to the Interpretation Review page, locate the interpretation to comment on, and click the appropriate link to submit a comment on the corresponding interpretation. Comment submissions will be accepted for 30-days after the interpretation letter is posted.

This section of the website below provides the ability to find regulations information including regulations parts, content of sections, and interpretations for regulations sections. A list of parts, identified by the part number and subject is also provided. To browse sections by part, click on the subject link below. You will be taken to the eCFR website to view sections for a part.

The eCFR is also searchable by keyword and other available options on the eCFR website. To search and browse regulations using the eCFR website, use the link below. For assistance, please send an email to PHMSA.Webmaster@dot.gov.

Search the eCFR

Interpretations Reference #

Search Tip: Use quotation marks to search for commonly used phrases, such as “gas transmission” or “cargo tank motor vehicle.”
E.g., 02/09/2021
E.g., 02/09/2021
Ref ID: Date Company Name Individual Name Response Document
07-0125 Dupont Automotive Systems Ms. Randylynn Bourassa View
07-0130 Dangerous Goods Advisory Council Mr. Frits Wybenga View
07-0076 Natural History Museum of Los Angeles County Mr. Leonard M. Navarro View
07-0099 Mr. Christopher M. Bruce  View
07-0067 Alcoa KAMA Mr. Chris Meeks View
07-0072 Sherwood, Harsco Corporation Ms. Mia R. Daniels  View
07-0039 Hapag-Lloyd (America) Inc. Mr. Robert F. Ahlborn View
07-0037 Horizon Lines Mr. Cliff Bartley  View
07-0097 McGowan Enterprises, Inc. Mr. Jim Falls View
07-0117 City Carbonic Sales & Service, Inc. Ms. Amy Morgan Bruecks View
07-0120 The Fertilizer Institute Ms. Pam Guffain  View
07-0102 Medical Services of America Mr. Wayne R. Cromley View
07-0114 North Pacific Paper Corporation Mr. Ross Lovie View
07-0096 Emergency Response and Training Solutions Mr. George Sabo View
07-0079 National Institute of Standards and Technology Mr. Larry Lucas  View
07-0092 Florida Power and Light Co. Mr. Frank Nesbihal, CHMM View
07-0090 Boston Scientific Corporation Ms. Julie Whitted View
07-0087 The Council on Safe Transportation of Hazardous Articles, Inc. Mr. John V. Currie View
07-0105 General Environmental Management, Inc. Alexander Amort View
07-0073 The Alpha Group Mr. Vince Panunzio View
PI-07-0104 Sutherland Asbill & Brennan LLP Mr. Andrew K. Soto View
07-0063 U.S. Coast Guard Sector Juneau Lieutenant Rob Nakama View
07-0085 J.J. Keller & Associates, Inc. Mr. Thomas J. Ziebell  View
07-0028 Line Pressures, Inc. Mr. Paul Graves View
07-0093 N. Wood Counter Laboratory, Inc. Ms. Marjory Crawford View
07-0082 City Carbonic Sales & Service, Inc. Ms. Amy Morgan Bruecks View
07-0086 Air Products and Chemicals, Inc Ms. Susan K. Leith View
07-0089 LND, Inc. Mr. Spencer B. Neyland View
07-0074 Veolia Environmental Services Ms. Jennifer Eberle View
07-0066 Network Environmental Systems Mr. Earl Thomas View
CHI-07-002 Minnesota Department of Transportation Mr. Michael Ritchie View
07-0070 Fire Protection Certification Mr. Edward O"Brien View
07-0062 Wisconsin Department of Natural Resources Ms. Gretchen S. Wheat View
07-0078 Bioject, Inc. Mr. Kris Richard  View
07-0071 PCS Sales, (USA) Inc Ms. Tracey G. Smith View
07-0069 Manager Transportation Regulations and Security Mr. Mark Connolly  View
06-0277 National Solid Wastes Management Association Ms. Alice P. Jacobsohn View
07-0032 Safety Division, Railroad Commission of Texas Mr. James. T. Osterhaus View
07-0048 JCI Jones Chemicals, Inc. Mr. D.L. Casmey  View
06-0241 LND, Inc. Mr. Spencer B. Neyland View
07-0060 Sandia National Laboratories Mr. Leighton Ford View
06-0270 Entegris, Inc. Mr. Kevin Bevis View
PI-07-0103 Kinder Morgan, Inc. Mr. Bruce Hancock View
06-0261 Wiley Rein & Fielding LLP Mr. George A. Kerchner View
PI-07-0102 Enterprise Products Company Mr. Joel E. Kohler, P.E. View
07-0053 Allied Universal Corporation Mr. Robin J. Eddy Bolte View
06-0228 Northern Air Cargo, Inc. Mr. Mark Smith View
07-0054 FedEx Express Mr. Marvin A. Sudduth View
06-0283 ISOTECH Laboratories, Inc. Mr. Dennis Coleman View
07-0042 Veolia Environmental Services Jennifer Eberle View