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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
98-0603 United Parcel Service Airlines Mr. Samuel S. Elkind View
98-0598 Truck Trailer Manufacturers Association Mr. Donald W. Vierimaa View
98-0597 The Association of Container Reconditioners Mr. Paul Rankin View
98-0018 Amoco ChemicalsMs. Vickie M. Wheeler Ms. Vickie M. Wheeler View
98-0514 North American Transportation Consultants, Inc. Mr. J. P. Gibbons View
98-0573 Mr. Bobby Roper View
98-0567 Weld-It Company Mr. Michael J. Young View
98-0425 Liquid Transport Corporation Mr. Frank L. Boone View
98-0543 SAFT America Inc Mr. Chip Wildes View
98-0426 American Crop Protection Association Mr. Thomas J. Gilding View
98-0533 Lockheed Martin Mr. George Gaskill View
PI-98-003 The Public Utilities Commission of Ohio Edward M. Steele View
98-0609 Hercules Incorporated Mr. L.L. Kerstetter View
98-0394 State of Connecticut Mr. Tom Metzner View
98-0395 Department of Environmental Protection Mr. Tom Metzner View
98-0526 Saturn Corporation Mr. Daniel T. McDonald View
98-0571 Girard Equipment, Inc. Mr. John Freiler View
98-0418 Air Products and Chemicals, Inc. Mr. Richard J. Lloyd View
98-0421 Boe Gases Mr. John N. Thompson View
PI-98-002 James S. Stites View
98-0602 G.H. Johnson & Associates, Inc. Mr. James A. Noone View
98-0562 Mr. Kent Blair View
98-0509 Wood Kote Products, Inc Mr. Gary P. Velikanje View
98-0083 USA Services, Inc. Mr. George Plum View
98-0553 Mr. Kent Blair View
98-0398 H.B. Fuller Automotive Company Mr. Gene Secor View
98-0551 Worthington Cylinder Corporation Mr. Steven T. Gentry View
CHI-98-002 Southern California Edison Mr. Manuel Zamorano View
98-0402 LAX Civil Aviation Security Mr. Frank L. Webb View
98-0502 Department of the Army Ms. Marcia C. Davies, Ph.D View
98-0577 National Tank Truck Carriers, Inc. Mr. John L. Conley View
98-0579 National Tank Truck Carriers, Inc. Mr. John L. Conley View
98-0582 National Tank Truck Carriers, Inc. Mr. John L. Conley View
98-0404 Cleanlites Recycling, Inc. Ms. Jeanne Hourani View
98-0393 Allantoic Systems Mr. Lee R. Zwiefelhofer View
98-0548 Ross Trucking Co., Inc. Ms. Nancy McKnight View
98-0559 Kold Ban Internal, Ltd. Mr. James O. Burke View
98-0019 Allantoic Systems Mr. Lee R. Zwiefelhofer View
98-0414 Hazmateam, Inc. Mr. Leo Traverse View
98-0512 Waste Management, Inc. Mr. Daniel L. Duncan View
98-0530 Roger L. Goodman, D.D.S., P.C. View
PI-98-001 Tennessee Regulatory Authority Glynn Blanton View
98-0519 The Defense Contract Management Command Ms. Jill E. Pettibone View
98-0600 Regulatory Compliance Services Mr. R. J. Reynolds View
98-0504 Minnesota Department of Transportation Mr. Michael Ritchie View
98-0587 Baltimore Cargo Tank Services, Inc. Mr. Roy N. Clark View
98-0591 Baltimore Cargo Tank Services, Inc. Mr. Roy N. Clark View
98-0528 Pacific Resource Recovery Mr. Bill Rosenthal View
98-0608 DuPont de Nemours &Co. Mr. Randolph Martin View
98-0560 Spectra Gases, Inc. Mr. William Miller View