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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
06-0033 Mr. Christian W. Solum View
06-0017 Martinair, Inc Mr. Rob Riggott View
05-0313 Chevron U.S.A. Inc. Ms. Patricia E. Lin View
05-0259 Akzo Nobel Chemicals Mr. Mark A. Connolly View
05-0310 Airgas, Inc Mr. Randy Porter View
06-0008 North Carolina State Highway Patrol Captain George E. Gray, Jr View
04-0068 Inland Paperboard and Packaging, Inc Mr. John H. Rutherford View
06-0013 Pennsylvania Department of Environmental Protection Mr. Frederick P. Walter, Jr. View
06-0029 Fortco Plastics, Inc. Mr. Stephen Jetter View
06-0030 TEN-E Packaging Services, Inc. Mr. Robert J. Ten Eyck View
06-0011 Mr. Lawrence J. Maron View
06-0014 Frontier Technology Corporation Mr. Edward F. Janzow View
06-0005 Byfield Marine Supply Mr. Keith L. Mauer View
06-0024 Allied Universal Corporation Ms. Robin J. Eddy Bolte View
05-0210 Sandia National Laboratories Mr. Leighton Ford View
04-0182 Occupational Safety Specialists Mr. Steve Laughlin View
05-0315 Global Logistics Services Ms. Joan M. Boardman View
05-0047 Venture Lighting International, Inc. Mr. Clinton M. Giannett View
05-0299 Akzo Nobel Chemicals Mr. Mark A Connolly View
05-0287 Airgas, Inc. Mr. John Anderson View
05-0318 Director, Manufacturing Mr. Mike Conway View
05-0001 Mr. Donald Stiger View
05-0233 Indiana Propane Gas Association Mr. John Shimer View
05-0238 Consultant Mr. Charles E. Tudor View
05-0317 Director, Manufacturing Jerry Jones, Ph.D. View
06-0004 Department of the Air Force TSgt. Jesse Rubalcaba View
06-0010 Pioneer Eclipse Corporation Ms. Genie G. Bost View
05-0241 Envirocare of Utah, LLC Mr. Mark Ledoux View
05-0307 Food Products Association Mr. Richard N. Jarman View
05-0285 Dangerous Goods Mr. Larry Snellings View
05-0301 ALK Technologies, Inc. Mr. Joseph Tufaro View
05-0304 Photographic Solutions, Inc. Mr. David Stone View
05-0216 J.B. Hunt Transport, Inc. Mr. Loren Wish View
05-0254 United States Department of Energy 171.8, 172.202 View
05-0245 Samirian Chemicals, Inc. Mrs. Debbie Andres View
05-0180 Airgas-SAFECOR Mr. John Anderson View
05-0298 The Dow Company Mr. Phil Stewart View
05-0167 Boasso America Corporation Mr. Tony Ortego View
05-0312 Wiley Rein & Fielding LLP Mr. George A. Kerchner View
05-0269 ASTAR Air Cargo Inc. Mr. Gerry G. Kefalinos View
03-0037 Regulatory Resources, Inc. Mr. Wade A. Winters, CET, CHMM View
05-0308 Lixi, Inc. Mr. Robert Savini View
05-0201 Mr. Michael J. Pangia, P.C View
05-0286 Service Transport Group Inc Mr. Thomas Guadet View
05-0207 The Fertilizer Institute Ms. Pamela D. Guffain View
05-0297 U.S Battery Manufacturing Company Mr. Terry Campbell View
05-0276 Mr. John Stolpe View
05-0300 Health and Environmental Excellence Center Ms. Cheryl A. Burke View
05-0267 Dangerous Goods Advisory Council Mr. Alan I. Roberts View
05-0295 DuPont SHE Excellence Center Ms. Cherry Burke View