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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
99-0213 Global Dynamics Corp. Mr. Jay Choi View
00-0004 It's A Gas, LLC Propane Cylinders Mr. Jeff Atkinson View
00-0381 Trailer Director Quality Distribution Mr. Charles Boudin View
99-0328 Quality Distribution Mr. Charles Boudin View
00-0291 Sakura Finetek U.S.A. Inc. Mr. Joseph Tan View
99-0207 ADCO Services, Inc. Mr. Len Warbiany View
98-0347 Ms. Denise M. Oas View
99-0210 Marsulex, Inc. Sam Reeder, PhD View
99-0327 View
99-0261 Greenebaum Doll & McDonald, PLLC Carolyn M. Brown, Esq. View
99-0253 JL Shepherd & Associates Ms. Mary F. Shepherd View
98-0335 National Institute of Standards and Technology Mr. T.G. Hobbs View
99-0262 Rootstown Office Ms. Carleen A. Ahrens View
99-0234 Ms. Karen Eve Leidigk View
99-0076 Commercial Vehicle Consultant Mr. Ralph B. Wood View
99-0290 Mr. Louis Sachs View
99-0291 Motor Carrier Compliance Office Captain Ken Carr View
99-0318 Printronix Ms. Kathryn Parham View
PI-99-0107 Arizona Corporation Commission Mr. Terry Fronterhouse View
99-0192 Bio-Safe America, Inc. Ms. Samantha Burdick View
99-0304 Keller & Heckman Ms. K. Jain Hershberg View
99-0243 Amtrol Inc. Mr. Joseph A. Lane View
99-0237 Bi-Met Company Mr. Steven T. Johnson View
99-0298 Micro-Med Industries, Inc. Mr. Charles N. Hendrix View
99-0307 Michels Pipeline Construction, Inc. Mr. Rod Day View
99-0289 Lee Products Company Mr. Faye Roy View
99-0259 HB Fuller Company Mr. Gene Secor View
99-0268 Heraeus Incorporated Mr. Franklin Hahn View
99-0288 Intech Services, Inc. Ms. Anne E. Johnson View
99-0305 U.S. Department of Transportation Mr. John D. Steinhoff View
PI-99-0106 Colonial Pipeline Company Mr. Stephen E. Gilliam View
99-0320 U.S. Marine Corps Air Station Mr. Dan Kesall View
99-0124 Arent Fox Kintner Plotkin Kahn, PLLC Mr. Paul Jackson Rice View
99-0269 Poitevent Carrère & Denègre L.L.P. Mr. Stanley A. Millan View
99-0280 Challenger Transportation, Inc. Mr. Jeff K. Ehrman View
99-0246 Quintiles Simirex Mr. Christopher Swift View
99-0306 California Highway Patrol< Mr. George Barber View
99-0059 Illinois Department of Transportation Mr. Terrence J. Moore View
PI-99-0105 City of Rolling Meadows Mr. Rodney A. Blane View
99-0162 Carib Ex Worldwide Ms. Juanita Caban View
99-0143 Chem-Nuclear Systems Kevin M. Lee View
99-0277 Thunderbird Cylinder, Inc. Mr. Fred A. Nachman View
99-0217 LaRoche Industries Inc. Mr. Carlton W. Hendrix View
99-0176 Kagan Aerospace Corporation Mr. Gregory Maynard View
99-0297 Neiman Marcus Direct Mr. Frank Ramirez View
99-0278 Condon & Forsyth, LLP Mr. David F. Rifkind View
PI-99-0104 Illinois Power Company Ms. Amy L. Hammond View
99-0235 Modern Safety Techniques Mr. Charles F. Martin, P.E. View
99-0258 Express Transport by Air Inc. Ms. Angela Flynn View
99-0065 Sacramento Blood Center Ms. Catherine J. Feiock View