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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 Sort ascending Company Name Individual Name Response Document
21-0089 Molecule Corp. Company Nick Talken View
21-0082 Onepoint4 Ltd. Peter Shelley View
21-0087 National Institute of Standards and Technology Mr. Larry Lucas View
21-0099 Lithium Battery Service GbR Eva Glimsche View
21-0076 American Cylinder and Safety Myles L. TenBroeck View
21-0105 Evonik Corporation Robert Miller View
21-0077 Oak Harbor Freight Lines, Inc. Jeff McLaughlin View
21-0053 National Fireworks Association Steve Houser View
21-0020 Transport Canada, Ontario Region Brent Grice View
21-0068 Kajuligan, Inc. Cliff Croft View
21-0086 OMG Inc. Bradley Bedard View
21-0091 Entegris James V. McManus View
21-0094 Scopelitis, Garvin, Light, Hanson & Feary, P.C. Timothy W. Wiseman View
21-0057 Hogan Lovells US LLP Latane R. Montague View
PI-21-0009 CH-IV Mr. Juan Carlos Rivadeneira View
PI-20-0014 Manatt, Phelps, and Phillips, LLP representing Chemoil Mr. Matthew Williamson View
21-0060 Massachusetts State Police Scott Maguire View
21-0085 Healthcare Waste Institute Darrel K. Smith View
21-0065 Smarter Sorting AJ Kenny View
21-0084 Koorsen Fire & Security Brick Keltner View
21-0043 American Bureau of Shipping Simone Goncalves View
21-0078 Remora Carbon Christina Reynolds View
21-0037 Law Offices of Steven W. Hansen Steven W. Hansen View
21-0066 Robert L. Beck View
21-0026 Airgas USA, LLC John Anderson View
21-0051 Railsback Hazmat Safety Professionals, LLC Rex Railsback View
21-0064 Ocean Network Express (North America) Inc. Lisa Stone View
21-0073 Superior Plus Propane Timothy Decker View
PI-21-0008 Audubon Field Services Mr. Bryan Louque View
PI-21-0003 Pennsylvania Public Utility Commission Ms. Stephanie M. Wimer View
21-0061 National Transportation Safety Board (NTSB) Rachael Gunaratnam View
21-0038 Momentive Performance Materials Ms. Kirsten Pink View
21-0054 TCIX Rail Keenan Moore View
21-0041 Mr. Robert J. Howell View
21-0058 KBI Paul D. Johnson View
21-0030 Wellmatics Joshua Howk View
21-0049 Wisconsin State Patrol Christopher Caldwell View
21-0067 Transportation Compliance Associates, Inc. Michael D. Alston View
21-0040 Department of the Army, Army Sustainment Command (ASC) ASC Packaging, Storage, and Containerization Center Logistics, Testing, and Applications Division Ryan Roberts View
21-0032R Bettis Asphalt & Construction, Inc. Cole Andersen View
PI-20-0015 RCP Inc. Mr. W. R. Byrd View
21-0052 Amazon Marianna Patterson View
20-0086 Cylinder Sales and Testing, LLC d/b/a Coastal Hydrotesting Jeffery Strong View
21-0027 ACTenviro Aaron Hayward View
21-0039 Tank Car Safety Kenneth Dorsey View
PI-19-0019 Arizona Corporation Commission Mr. Eric Villa View
PI-21-0006 Shell Pipeline Company LP Ms. Deborah Price View
21-0048 EnerSys Steven Spease View
20-0096 NEX-XOS Worldwide, LLC Saul Mishkin View
21-0047 Safeway Transportation Richard Elliott View