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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
17-0071 A123 Systems, LLC Joe Shi View
17-0060 Council on Safe Transport of Hazardous Articles, Inc. L'Gena Shaffer View
17-0129 United Brands Jimmy Zahriya View
17-0138 Labelmaster Jim Shimko View
17-0107 Catalina Composites Ray Denny View
17-0024 Currie Associates, Inc. Tom Fergison View
17-0089 Wisconsin State Patrol SE Region Mark Butler View
17-0100 Lockhead Martin Aeronautics Company Rebecca Stokes View
17-0083 Gold Tank Inspection Service Inc. Aris Antoniou View
17-0097 Sheetz, Inc. Frank Scott View
17-0087 Safecraft Inc. Steven Baker View
17-0109 Hunting Titan, Inc Joe Murphy View
17-0062 Carbotainer SL Antonio Ruiz View
17-0127 Sandia National Laboratories Shawn Colborg View
17-0106 3M Cottage Grove Mr. Allen Grantham View
17-0068 Duke Energery Corporation Mr. Charles Denny View
17-0041 WNWN International Mr. Ed Krisiunas View
17-0108 Lockheed Martin Christian Calvo View
17-0035 Mr. Jared Sherman View
17-0085 Mr Evan Mills View
17-0094 Entegris Inc. Mr. James McManus View
170077 Texas Highway Patrol Mr. Brad Gibson View
170067 Naval Station Everett Mr. Andrew Roley View
17-0074 Western International Gas & Cylinders, Inc. Ms. Kathy McKenzie View
17-0066 Tyco Fire Protection Products Ms Kym Seth View
17-0082 Save the Situation Ms. Eva Glimsche View
17-0098 KWS Training, Inc. Mr. Ken Summer View
17-0075 Elkhart Plastics, Inc Mr. Jason Furrer View
16-0198 C&J Energy Services Ltd. Mr. George Doggett View
16-0169 Kalitta Air LLC Mr. Tim Shaw View
160085R Office of Motor Vehicle Enforcement Captain Dean House View
17-0057 Elkhart Plastics, Inc. Mr. Jason Furrer View
15-0140 Inmark Packaging Mr. Jay Johnson View
17-0077 Texas Highway Patrol Brad Gibson View
11-0165R Thermofisher Ms. Melissa Russell 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-17-0012 Northern Arizona University Mr. Jonathan Heitzinger View
PI-17-0008 AmeriGas Propane, LP Mr. David Hedrick View
PI-16-0006 Statoil Oil and Gas LP Mr. Ronnie Speer View
PI-17-0013 Automatic Propane Gas and Supply Mr. David Dupuy View
PI-16-0011 Counsel to North Dakota LNG, LLC Mr. Greg H. Williams View
PI-17-0002 West Virginia Department of Environmental Protection Ms. Ruth M. Porter 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
17-0038 RASIRC Mr. Ryan Woon View
17-0063 Morton Plant Mease Health Care, Inc. Ms. Beth Schelle View