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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
17-0035 Mr. Jared Sherman View
16-0169 Kalitta Air LLC Mr. Tim Shaw View
17-0074 Western International Gas & Cylinders, Inc. Ms. Kathy McKenzie View
11-0165R Thermofisher Ms. Melissa Russell View
17-0077 Texas Highway Patrol Brad Gibson View
15-0140 Inmark Packaging Mr. Jay Johnson View
PI-17-0007 The Dow Chemical Company Ms. Jennifer Ashcraft View
PI-17-0017 G2 Integrated Solutions Mr. John A. Jacobi View
PI-17-0016 Home Owner Mr. William F. Limpert View
PI-16-0006 Statoil Oil and Gas LP Mr. Ronnie Speer View
PI-17-0008 AmeriGas Propane, LP Mr. David Hedrick View
PI-17-0013 Automatic Propane Gas and Supply Mr. David Dupuy View
PI-17-0012 Northern Arizona University Mr. Jonathan Heitzinger View
PI-17-0002 West Virginia Department of Environmental Protection Ms. Ruth M. Porter View
PI-16-0011 Counsel to North Dakota LNG, LLC Mr. Greg H. Williams View
PI-17-0001 G2 Partners Mr. John A. Jacobi View
11-0165R Thermofisher Ms. Melissa Russell View
15-0140 Inmark Packaging Mr. Jay Jonson
17-0067 Public Works - Naval Station Everett Andrew Roley View
16-0202 Valley View Industries, Inc Timothy Kenney View
17-0058 Hazmat Environmental Group Mr. Vince Phillips View
17-0086 CFI Mr. Jeff Messer View
17-0018 AccuBeat Ltd. Mr. Jonathan Gurten View
17-0072 Navarro Research and Engineering, Inc Lee Stevens View
16-0183 HazMat Resources, Inc Daniel Shelton
17-0046 TT Club Mr. Michael Yarwood View
17-0069 The Ohio State University Mr. Mike Swick View
17-0053 View
17-0038 RASIRC Mr. Ryan Woon View
16-0204 Evonik Corporation Robert Miller View
16-0194 Vectron International, Inc Dr. Ram Arvikar View
17-0063 Morton Plant Mease Health Care, Inc. Ms. Beth Schelle View
17-0056 FIBA Technologies, Inc Chris Adams View
17-0055 Waste Management Sustainability Services Mr. Brian Biancavilla View
16-0143R Mark Hawk View
17-0052 Kidde Residential and Commercial Division Mr. Ronald Mauney View
15-0173 The Davey Tree Expert Co. Mr. Chuck Daum View
17-0004 Law Offices of Paul A. Lange, LLC Mr. Paul Grocki View
17-0026 Mr. John Hardridge View
17-0037 Paper Battery Company Mr. Peter Ellenwood View
17-0022 Golder Associates, Inc. Mr. Benjamin Huron View
16-0207 Kinross EMS Ms. Deb McBane View
17-0048 Jackson Energy/ Capitol Distributing Mr. Rob Berrier View
17-0023 Solvay CYTEC Group Mr. Geoffrey De Vinney View
17-0039 Williams International Mr. Stan Harrison View
17-0042 Trinity Industrials. LLC Mr. Greg McRae View
17-0059 FIBA Technologies Affairs Mr. Christopher Adams View
17-0031 Daniels Training Services, Inc. Mr. Daniel Stoehr View
16-0196 PonyPak Mr. William Messner View
16-0070 DHL Global Forwarding Ms. Dolly Welk View