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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
PI-10-0007 City of LaGrange Mr. Patrick Bowie View
10-0006 Hydro-Test Products, Inc. Mr. Tom Sauta View
CHI-10-0114 FMCSA Office of Enforcement and Compliance View
PI-10-0011 Judge Baughman View
10-0135 Naval Surface Warfare Center Energy Power & Interconnect Technologies Division Mr. Mark Tisher View
10-0129 Bringham McCuchen LLP Mr. Robert N. Steinwurtzel View
10-0132 Entergy Services, Inc. Mr. Joe Hantz View
10-0094 Akzo Nobel Chemicals, Inc. Mr. Mark A. Connolly View
10-0151 Chemical Solutions Mr. Neil M. Canter View
10-0104 Wacker Polymers Mr. Edwin McIntyre View
10-0110 Canadian Defense Liaison Staff Col. D.T. Erickson View
PI-10-0005 Fulbright & Jaworski L.L.P. Ms. Lisa M. Tonery View
10-0120 Minnesota Department of Transportation Office of Freight and Commercial Vehicle Operations Mr. Michael Ritchie View
10-0117 Polymet Alloys, Inc. Mr. Matt Gilmore View
10-0108 Department of City Development City of Milwaukee Mr. Clyde Hamer View
10-0124 Food Safety Net Services LTD Mr. Timothy J. Santy View
10-0123 Cart, Inc. Mr. Sam Cook View
10-0045 Department of Ecology Mr. Gerald French View
PI-10-0021 Keppel & Miozza View
09-0240 Dangerous Goods of America Mr. Fred A. Romero View
10-0035 High Angle Construction, Inc. Mr. Eric Lieberman View
10-0112 Micro Scientific Industries, Inc. Mr. Jack Wagner View
10-0069 Battelle National Biodefense Institute (BNBI) Ms. Jill C. Santacroce View
10-0105 Bergeson & Campbell, P.C. Mr. Christopher R. Bryant View
10-0063 Colorado Department of Public Health and Environment, Radioactive Materials Unit Mr. Ed Stroud View
10-0089 Essex Cryogenics of Missouri, Inc. Mr. Ken Seise View
09-0103 Hapag-Lloyd (America), Inc. Mr. Robert F. Ahlborn View
10-0044 Lockheed Martin Missiles & Fire Control Mr. Melvin D. Schubert View
10-0041 Britt & Brown LLP Mr. Andrew Brought View
10-0072 Transportation Development Group Mr. Jim Powell View
10-0099 Sporting Arms & Ammunition Manufacturers Institute, Inc. Mr. Rick Patterson View
10-0101 Jefferson Lab Thomas Jefferson National Accelerator Facility Mr. Thomas Briggs, PE View
10-0118 Fox Racing Ms. Jennifer Lucia View
10-0083 Chemical Sector Coordinating Council Mr. Dan Walters View
10-0090 Industrial Packaging Alliance of North America Mr. John McQuaid View
10-0100 Wilhelmsen Ships Service Mr. Dave Finlay View
09-0180 Burdette & Associates, Inc. Mr. Michael Burdette View
09-0088 Roadrunner Rocketry, Inc. Mr. Bob Korman View
10-0088 Dyno Nobel, Inc. Mr. Mark Anderson View
10-0068 FedEx Express Corporation Mr. David Littlejohn View
10-0103 Calfrac Well Services Corp. Mr. Dave Mykyte View
10-0076 Hyundai America Shipping Agency, Inc. Mr. Herb Giles View
10-0079 Air Liquide Industrial U.S. LP Mr. Steven Bilger View
10-0087 US Dynamics Corporation Mr. George Jantzen View
10-0085 Canadian Material Support Group Captain E.M. Steele View
10-0043 Gefahrgutberatung/Gefahrgutausbilding Mr. Jens-Thomas Rueckert View
10-0067 SDS, Inc. Mr. Stephen Nesteriak View
10-0075 Landstar Transportation Logistics Mr. Wes Pace View
09-0245 Mr. Andrew Abrams View
10-0084 Commercial Chemical Mr. David L. Turnage View