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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-23-0008 Pennsylvania Public Utility Commission Mr. Adam D. Young View
22-0025 University of Rhode Island Nic Englehart View
22-0129 American Bureau of Shipping Ms. Simone Goncalves View
22-0058 Heil Trailer Mr. Charles Gilson View
22-0095 Environmental Resource Center Kristie Absher View
23-0010 Advanced Printing Solutions Bill Booth View
PI-11-0013 New Mexico Gas Company Ms. Deborah Brunt View
22-0062 Larson Berg & Perkins PLLC James A. Perkins View
22-0085 Aggreko Mr. Chad Thibodeaux View
22-0134 SMBC Rail Services LLC Dan Welch View
22-0069 Senergy Petroleum Mr. Deven Hallen View
22-0121 DOT Training Solutions Arturo Prado View
22-0122 David Fletcher View
22-0094 AllTranstek, LLC Larry Loman View
22-0013 DuPont EHS Center of Excellence Mr. Jeffrey D. Shields View
22-0123 R@K Testing Rich Kovaleski View
22-0021 Matson Navigation Company Mr. James Owen View
22-0028 DOT Training Solutions Mr. Randy Decker View
22-0061 Matson Navigation Company Mr. James Owen View
22-0050 Mayo Clinic Mr. Travis Brandt View
22-0072 Coty Riverside Distribution Center Ms. Janice Hayes View
22-0113 Totex Manufacturing, Inc. Jim Sides View
22-0138 AllTranstek, L.L.C. Mike Tait View
22-0071 W.E. Train Consulting Mr. Gene Sanders View
22-0111 State Industrial Products Travis Arledge View
22-0133 Usher Transport Jerry Hudson View
22-0131 Powin Thomas Kerr View
22-0029 Belshire Environmental Services Inc. Bear Bridges View
22-0037 Linde Gas & Equipment Inc. Mike Stephens View
22-0064 Total Compliance, LLC Chris Heminger View
21-0110 Matson, Inc. Cliff Bartley View
22-0112 Oak Harbor Freight Lines, Inc. Jeff McLaughlin View
22-0110 Environmental Resource Center Kristie Absher View
22-0106 Clean Earth Nicholas Prevosti View
22-0048 Tom Morales View
22-0063 M-Tac Trucking Compliance LLC Brian A. McGuire View
22-0035 Linde Gas & Equipment Inc. Mike Stephens View
22-0034 CTI and Associates, Inc. Terri Zick View
PI-22-0018 XTO Energy, Inc. Mr. Jameson Gowin View
22-0066 Ameristar Air Cargo, Inc. Pat Hulsey View
22-0086 Fujitrans USA Inc. Laura Warren View
22-0102 Transportation Development Group, LLC Jim Powell View
22-0120 Hazmat Safety Consulting, LLC Robert Richard View
22-0083 Pilot Chemical Company Megan O’Connor View
22-0090 Hunting Titan Joseph Murphy View
22-0051 Inliner Solutions Wayne W. Carver View
22-0007 Consolidated Nuclear Security Chris Carthel View
22-0010 CryoLogistics Refrigeration Technologies Ltd. Rodger Talstra View
22-0044 Transportation Development Group, LLC Jim Powell View
22-0080 Arkema – Health Environment and Safety Steve Schulte View