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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
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
22-0036 Haz-Mat One Mr. Travis Hillmer View
23-0021 W. R. Grace & Co – Conn. Paul Errichetti View
22-0126 UL Solutions Mr. Kevin Skerrett View
22-0057 Department of The Army Mr. Thomas Kudasz View
22-0116 Total Technic Total Technic View
23-0004 APRAGAZ (Notified Body 0029) Chris Vleugels View
23-0034 KTM North America, Inc. Mr. John Hinz View
22-0117 Mr. Nick Wright View
23-0036 National Association of Fire Equipment Distributors Mr. David A. Pelton View
23-0015 UralKali Trading Marcel Cisneros View
22-0130 American Cylinder and Safety Myles Leland TenBroeck View
23-0017 Vantage Specialties, Inc. Mr. Donovan Robin View
PI-23-0009 CH-IV International Mr. Lex De Groot View
22-0118 Tanner Industries, Inc. James Klucsarits View
23-0029 Northrop Grumman Corporation Bob Keller View
23-0031 Essex Industries, Inc. Ario Estrada View
22-0078 Crestwood Transportation Mr. Jared Sharp View
22-0099 Ameteck Specialty Metal Products Mr. Dave Kraemer View
22-0101 Entegris Inc. Mr. James V. McManus
22-0033 DOT Safety Solutions Randy Decker View
23-0019 AET Environmental, Inc. Frank Virginia View
23-0001 Petra Industries, LLC Mr. Tyler Scott View
23-0033 Sensors, Inc. Mr. Doug Heisler View
23-0006 Sea Lamprey Control Centre Mr. Paul Kyostia View
PI-23-0004 Integrity Plus Mr. Pat Westrick View
22-0132 The Hartford Steam Boiler Inspection and Insurance Company Bruce K. Redfield View
22-0067 Kidde Aerospace and Defense Mark Fazzio View
22-0092 Independent Cylinder Training Amy Morgan Bruecks View
23-0028 Arkema Inc. Christina M. Kurtz View
23-0005 Steve Laughlin View
PI-23-0002 Illinois Commerce Commission Mr. Matthew L. Harvey View
PI-23-0003 Riverfront Exploration, LLC Ms. Jennifer Sebo View
22-0014 I.C.E. Service Group & SPS Strategic Packaging Systems Mr. Kurt Colborn View
PI-23-0001 Pacific Gas & Electric Company Mr. Philip Simpkins View
22-0052 Arkema – Health Environment and Safety Steve Schulte View
22-0109 Pacific Gas & Electric Timothy Hewitt View
22-0047 Bureau Veritas Inspection and Insurance Company Edgar A. Whittle View
PI-22-0015 Anheuser-Busch, LLC Mr. Kevin Fahrenkrog View