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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).

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 Company Name Individual Name Response Document
23-0105 SET Environmental, Inc. David Olsen, Jr. View
23-0065 W. R. Grace & Co. Mr. Paul Errichetti View
23-0101 NRS Ocean Logistics Ltd. Ms. Nicole Enright View
23-0076 Mr. Tristan Amberger View
23-0075 Roy Kluthe View
24-0024 Parker Hannifin Lord Corporation Erik Steinbeck View
23-0102 American Industrial Transport, Inc. Roger Dalske View
22-0087 Olin Corporation Daniel T. Stein View
PI-23-0018 State of Washington Utilities and Transportation Commission Regulatory Mr. Scott Rukke View
23-0096 Airborne Labs International, Inc. Aniyah Volpe View
23-0103 Logistics Specialist IV Shelly Stampfler View
24-0002 International Isotopes Inc. John J. Miller View
24-0007 ABC Nitrogen Service Corp Aimee Fontenot View
23-0009 DOT Training Solutions Rex Railsback View
23-0092 Encore Container Chas Key View
23-0085 Texas Highway Patrol Dustin Henderson View
22-0107 Roadrunner Transportation System LLC Mr. Karl Kronau View
23-0027 Electronic Fluorocarbons Mr. Jason Bombard, PE View
23-0045 L-H Battery Company, Inc. Mr. Rick Riggle View
23-0018 LDJ Manufacturing, Inc. Mr. David J. Ladwig View
23-0087 North Carolina Department of Health and Human Services Kristi Jenkins View
23-0079 Hazmat Safety Consulting, LLC Ryan Paquet View
PI-23-0017 US Bureau of Land Management Ms. Melanie Barnes View
23-0094 DCMA-TDLTC Douglas Connell View
23-0088 Wabtec Corporation Vincent M. Melillo View
23-0082 The University of Alabama at Birmingham Justin Roth View
23-0058 Carbochem Inc, Mr. Gavin Kahn View
23-0056 Hazmat Resources, Inc. Mr. Daniel Shelton View
23-0008 Leschaco, Inc. Mr. Hien Le View
23-0064 TEN-E Packaging Services, Inc. Robert Ten Eyck View
23-0069 Elizabeth M. Richardson View
23-0091 Honda Development and Manufacturing of America Mr. Joe Williamson View
23-0063 Hazmat Safety Consulting, LLC Mr. Robert Richard View
23-0068 UL Solutions Kevin Skerrett View
23-0074 Raytheon Steven W. Steuer View
PI-23-0010 B3PE LLC Mr. Brad Bean View
23-0012 Kansas Highway Patrol Technical Trooper Nick Wright View
23-0057 WMG Inc. Mr. John Grinley View
23-0054 Union Tank Car Company Jon Schultz View
23-0071 Council on the Safe Transportation of Hazardous Articles L’Gena Shaffer View
23-0003 Denver Fire Department Chris Bartlett View
22-0139 WM Pacific Northwest Haydon Morris View
23-0043 Qnergy Mr. Allen Peterson View
PI-22-0010 Navajo Tribal Utility Authority Mr. Antony M. Davison View
22-0070 Scopelitis, Gavin, Light, Hanson & Feary, P.C. Mr. Timothy W. Wiseman View
23-0014 Fleener Consulting LLC Mr. Arthur Fleener View
23-0040 DHL Global Forwarding (RADIX International) Dennis Raymund V. Franco View
23-0051 Orbiter, Inc. Gregory M. Stewart View
22-0128 D.T. Gruelle Company Group LLC Mr. James F. Thornton View
23-0025 Perkins Coie Edward (Ted) Boling View