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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
03-0161 ARUP Laboratories Mr. Paul H. Brinton View
03-0190 Graef E&S Consulting Services Mr. Warren D. Graef, BAAS, CHMM View
02-0315 Keller and Heckman LLP Mr. Terrence D. Jones View
03-0177 A.I.D., Inc. Mr. Donald Brittingham View
03-0143 Optical Dynamics Corporation Mr. John Gardner View
03-0091 NRS America Inc. Mr. Domenico Masi View
03-0157 Mr. Clark B. Huggins View
02-0290 Raymond Schaffer View
03-0173 Minnesota Department of Transportation Mr. Michael Ritchie View
03-0154 Brenntag Mid-South, Inc. Mr. A.B. Eargood View
03-0105 Chautauqua Airlines Mr. John E. Martiney View
02-0259 Minnesota Department of Transportation Michael Ritchie View
03-0174 Woodside Inc. Andrew Woodside Ph.D. View
02-0139 Neeley Sales Co. Inc. Jason Perrone View
03-0146 Department of California Highway Patrol Officer George Barber, CHPO, 10665 View
03-0163 Defense Logistics Agency Ms. Janet Cravener View
03-0119 Science Kit & Boreal Laboratories Mr. Rupert Zellner View
03-0101 Transportation Safety Compliance Service Mr. Darwin D. Garvin View
02-0304 PACE International Union Rickie Bearden View
02-0130 Argus Fire Control Bruce J. Euler View
03-0025 HAZMATPAC Certified Packaging Mr. Donald H. Hausmann View
02-0080 Allied Universal Corp. Robin J. Eddy Bolte View
02-0141 The Chlorine Institute, Inc. Gary F. Trojak View
02-0318 Honeywell Barbara Konrad View
03-0158 Pillsbury Winthrop Mr. David M. Hernandez View
03-0035 Riddick Engineering Corporation Mr. Chris J. Teas, PE View
03-0052 Tempu Marketing, Inc. Ms. Toi Phillips View
03-0073 The Embalmers" Supply Company Mr. John R. Jackson View
03-0128 Bioconvergence, Inc. Mr. Scott Kobryn View
03-0130 New York State Department of Environmental Conservation Division of Solid and Hazardous Materials Mr. Paul R. Counterman, P.E. View
03-0151 Dominion Generation Mr. Doug Noce View
03-0002 Sunoco, Inc. Mr. Michael Alston View
02-0330 SMI Companies Michael W. Splane View
CHI-03-001 Department of California Highway Patrol Commissioner Helmick View
02-0305 Keller and Heckman LLP Michael F. Morrone View
03-0139 Brink's U.S. Mr. Stan Turbyfill View
03-0090 Lansmont Corporation Ms. Tramy Lieu View
03-0065 Eliokem, Inc. Mr. Dennis McMahan View
03-0011 Mr. John L. Hoffer View
03-0085 Core Foam Mr. Richard Porter View
02-0314 Aero Vironment Inc. Erica Jenkins View
03-0114 Dupont Global Services Business Mr. Randolph Martin View
03-0135 American Trucking Associations Mr. Richard Moskowitz View
03-0018 Arkansas Children's Hospital Mr. Wes Ware, BS, RRT, NREMT View
03-0030 Department of the Army Mr. Patrick M. Haas, P.E. View
03-0077 Waste Technology Services, Inc. Mr. T.L. Nebrich, Jr. View
03-0066 Patrick J. Kelly Drums, Inc. Mr. Harold Aranow View
03-0093 Riddick Engineering Corporation Mr. Chris J. Teas, PE  View
03-0096 Fisher Chemicals Ms. Jeanette DeGennaro View
PI-03-0102 City of Mesa Mr. Michael Comstock View