USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

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).

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.

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 Sort ascending Company Name Individual Name Response Document
22-0068 Detroit Scrap Consulting Services Ty Cox View
22-0043 Alabama Liquefied Petroleum Gas Board W. Mark Nelson View
22-0045 Parker Hannifin Corporation Erik Steinbeck View
22-0046 Entegris Inc. Jim McManus View
22-0015 ICE Service Group & SPS Packaging Systems Kurt Colborn View
PI-22-0013 BGC Engineering Inc. Mr. Mark Zellman View
22-0049 Linde Gas & Equipment Inc. Mike Stephens View
22-0020 Justin Lacy View
22-0011 Betts Industries, Inc. David J. Adams View
22-0022 Duke Energy Corporation Charles Denny View
21-0069 UL LLC Mr. Blake Shugarman View
21-0098 Dominion Energy Mr. Tim Carter View
22-0006 Daniels Training Services Inc. Mr. Daniel Stoehr View
22-0009 Council on Safe Transportation of Hazardous Articles L’Gena Shaffer View
22-0039 DHL Global Forwarding Dennis Raymund V. Franco View
22-0032 Shanghai Research Institute of Chemical Industry Testing Company, Ltd. Bin Fan View
PI-22-0011 International Union of Operating Engineers, Local No. 49 Mr. Christopher J. Chantry View
22-0024 Keller and Heckman, LLP Trent Doyle View
21-0097 East Bay Law Andrew W. Shalaby View
21-0102 George W. Wright & Associates, LLC Doris Soran View
22-0004 OSM, LLC Ann Fukunaga View
22-0005 Desert Isle Inc., Lahaina Air Conditioning, Ltd. Peter Faulkner View
PI-22-0007 New Fortress Energy Mr. Brannen McElmurray View
PI-22-0008 National Transportation Safety Board Ms. Sara Lyons View
PI-22-0006 CH-IV Regulatory Mr. Juan Carlos Rivadeneira View
22-0017 Old Bridge Chemicals, Madison Industries, Inc. Sandy Volk View
22-0001 ShipMate, Inc. Steven Charles Hunt View
22-0019 CBC Brazilian Cartridge Company Mariele Aparecida Nonis Munhoz View
PI-22-0004 On behalf of Philadelphia Gas Works Regulatory Mr. Joel Greene & Ms. Sarmentero Garzón View
19-0018R Council on Safe Transportation of Hazardous Articles Tom Ferguson View
22-0008 Public Utilities Commission of Ohio Tom Forbes View
22-0012 Regulatory Resources, Inc. W. A. Winter View
07-0166R CTC Certified Training Co. Darrel K. Garton View
PI-21-0007 Puget Sound Energy Kaaren Daugherty View
22-0003 Ordnance Lab LLC Sean Lindley View
21-0113 TEN-E Packaging Services, Inc. Robert Ten Eyck View
21-0062 Institute of Makers of Explosives Susan JP Flanagan View
21-0115 Intermodal Tank Transport Jasmine Builes View
PI-22-0001 I.B.E.W. Local Union 503 Ms. Melissa Kurtz View
21-0103 Eos Energy Storage Heidi Countermine View
21-0059 XPO Logistics Ms. Marie Copeman View
21-0107 Amanda White View
21-0071 Air General, Inc. Charles A. White View
21-0112 Sheetz, Inc. Roy Terwilliger View
21-0074 Commercial Vehicle Safety Alliance Collin B. Mooney View
21-0100 Hydro-Test Products, Inc. Carlos Graca View
21-0101 Hydro-Test Products, Inc. Carlos Graca View
21-0090 High Precision Gas Mr. Justin Wai View
21-0095 DynaEnergetics US Inc. Mr. Ed Zinsmeyer View
21-0096 Imperative Chemical Partners Shawn Melson View