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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
17-0021 Phase Four, Inc. Mr. Daniel Nash View
17-0010 Baker & McKenzie LLP Ms. Jennifer Trock View
17-0012 Couch Helicopter Ms. Bridgett Couch View
16-0195 CARGOpak Corp. Mr. Robert Smith View
16-0201 EnviroServices & Training Center, LLC Mr. Gregory Perry View
16-0197 AECOM Ms. Erin Jarman View
17-0016 Energy & Natural Resources Industries and EHS & Sustainability Products Mr. Brian Harmon View
16-0193 Scopelitis, Garvin, Light, Hanson, Feary, P.C. Mr. Timothy Wiseman View
17-0030 Quantum Fuel Systems Mr. Tae Kim View
17-0019 Nissan Group of North America Mark Marson View
17-0009 Airborne Labs International, Inc. Mr. Tony Amato View
17-0002 Defense Logistics Agency Mr. John King View
17-0027 Vianna Zimbel Consultting Ms. Vianna Zimbel View
16-0125 UPS Airlines Mr. Bob McClelland View
16-0082 Truck Trailer Manufactures Association (TTMA) Mr. John Freiler View
17-0005 Entegris Mr. Quentin Yarbrough View
17-0033 Environmental Resource Center Ms. Rebecca Spaulding View
17-0034 R&R Trucking, AATCO, NEI Mr. David Vargyas View
17-0028 Ball Food Aersol Mr. John Blum View
17-0014 Chevron Phillips Chemical Company LP Mr. Richard Norl View
16-0178 ICL Americans Mr. Gregory Phillips View
17-0029 Thatcher Transportation, Inc. Mr. Brent Olsen View
16-0203 AECOM Erin Jarman View
17-0007 Schuster Metals, LLC Mr. John Lehman and Mr. Samuel Essak View
15-0239 Inmark Packaging Mr. Jay Johnson View
16-0093 Broadcom Limited Mr. Richard Laudano View
16-0189 CTI and Associates, Inc. Ms. Terri Zick View
16-0184 Mr. Eric Fishman View
17-0006 Baker Hughes Mr. Joseph Murphy View
17-0001 MIdway USA Mr. Bradley Spears View
17-0011 Alchem Chemical Company Mr. Johnny Johnson View
16-0168 OneCIS Insurance Company Mr. Ed Whittle View
17-0015 Mr. Richard Lloyd View
16-0187 Swagelok Northern California Mr. Cameron Banks View
16-0150 Entegris Mr. John Gaudreau View
16-0205 W. T Bell International Inc. James Rairigh View
16-0170 Bancroft Hinchey Ltd Mr. Chris Hinchey View
16-0188 Propetro Tony Garcia View
16-0054 Infotrac, Inc. Mr. Jason Kob View
16-0172 DGI Training Mr. Sean Kelly View
16-0155 Baker Hughes Mr. Keegan Ritchie View
16-0009 Innovative Safety Solutions, Inc. Mr. Albert Calkin View
16-0176 SGS Petroleum Service Corporation Mr. Glenn Gillaspia View
16-0010 Mr. Jason Miller View
16-0111 MansourGavin, LPA Mr. Jeffrey Embleton, Esq View
16-0160 URS Corporation Mr. Andrew Romach View
17-0013 Berlin Packaging Gary Lindsey View
16-0143 Mr. Mark Hawk View
16-0200 Teleflex Mr. Jay White View
16-0118 Public Utilities Commission of Ohio Mr. Tom Forbes View