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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
15-0149 Tailgate In A Box Mr. Matthew MacLean View
15-0223 Lloyd's Register EMEA Mr. Nigel Tijou View
15-0217 Wacker Chemical Corporation Mr. Michael Strong View
15-0203 FIBA Technologies, Inc. Mr. Christopher Adams View
15-0190 Worthington Industries Mr. Steve Gentry View
15-0205 Air General Inc. Mr. Dennis Franco View
15-0213 Independent Cylinder Training Ms. Amy Bruecks View
15-0136 Mr. Edwin Van Schoick View
15-0206 Valley Building Center Mr. David French View
PI-15-0011 National Oilwell Varco L.P. Mr. John K. Arnold View
15-0215 Dangerous Good Logistics Solutions, Inc. Mr. Kevin Lapp View
15-0107 Northland Services, Inc. Mr. Scott McElhoe View
15-0163 MPS Group Ms. Cynthia Walczak View
16-0038 Lear Corporation-Guilford Mills Ms. Laura Jones View
15-0247 Infineum USA L.P. David Bower, Ph.D. View
15-0145 Northern Air Cargo, Inc. Mark Smith View
15-0202 Morpho Detection, LLC. Aric Tillberg View
15-0092 Inmark Packaging Mr. Jay Johnson View
15-0200 Kidde Technologies, Inc. Mr. Brett Standifer View
14-0241 Horizon Hobby, LLC Mr. Travis Morenz View
15-0031 Specialty Transportation and Regulatory Services Mr. Joe Connelly View
15-0175 Mr. Elliot Apland View
15-0209 Renessenz LLC. Mr. John Hinson View
15-0220 KTM North America, Inc. Ms. Cheryl Webb View
15-0176 ARKEMA Inc. Ms. Christina Kurtz View
15-0195 Prairie Island Nuclear Generating Plant Mr. Clay Sweet View
15-0152 DiSorb Systems, Inc Mr. Ted McLaughlin View
15-0063 Howard Sheppard, Inc. Mr. Michael Kitchens View
15-0106 Mr. Daniel Zirzow View
PI-15-0007 Rhode Island Division of Public Utilities and Carriers Mr. Don A. Ledversis View
PI-15-0008 Caelus Energy Alaska, LLC Mr. John A. Jacobi View
15-0170 Inmark Packaging Mr. Jay Johnson View
15-0158 U.S. Water Services Ms. Lisa L. Neumann View
15-0212 Paraco Gas Mr. David Latourell View
15-0154 Inmark Packaging, Inc. Mr. Jay Johnson View
15-0184 The Chemours Company Mr. Randolph Martin View
15-0191 Graco, Inc. Mr. Eric Lillyblad View
15-0179 John Deere TCAO Mr. Brad Storm View
15-0224 Schneider National Bulk Carriers Ms. Shannon Schick View
16-0075 Bureau of Dangerous Goods, LTD. Sandra Harding
15-0204 Crowley Liner Service Mr. Michael Lesser View
15-0178 Miller Transportation Services, Inc. Mr. Kenny Prather View
15-0189 Kajuligan Corporation Mr. Clifford Croft View
15-0169 Amazing Products Inc. Ms. Jackie Skaggs View
15-0222 COWAN Mr. J. David Shaeffer View
15-0118 National Association of Fire Equipment Distributors Mr. Norbert Makowka View
15-0242 AmeriGas Propane Mr. Christopher Wagner View
14-0215 U.S. Environmental Protection Agency Ms. Nancy Fitz View
15-0131 Tyco Fire Protection Products Mr. Josh Lepinski View
15-0242 AmeriGas Propane Mr. Christopher Wagner View