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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
11-0046 Chart Industries Mr. Dan Bricker View
11-0058 Airspeed Press Mr. Steve Lindblom View
10-0125 Anitox Corporation Kurt Richardson, Ph.D. View
10-0146 Clean Harbors Environmental Services, Inc. Mr. Anthony Cellucci View
11-0027 The Council on Safe Transportation of Hazardous Articles, Inc. Mr. Thomas W. Ferguson View
10-0059 Bureau of Waste Prevention Massachusetts Department of Environmental Protection Mr. Bill Sirull Chief View
11-0023 BioStorage Technologies Ms. Darcy Britt View
10-0171 AWE Mr. David A. Cocks View
09-0211 ChemStation International Mr. Scott Meridith View
11-0035 Department of the Army Mr. Daniel A. Maham View
11-0051 Reckitt Benckiser, Inc. Mr. Richard Hessen View
11-0054 Environmental Management Ms. Misha Gonzales View
10-0259 Airgas SAFECOR. Mr. Jon Anderson View
11-0029 Department of the Army Mr. Daniel A. Maham View
09-0236 Department of State INL/A Mr. James A. Sherman View
11-0043 International Vessel Operators Dangerous Goods Association Mr. John V. Currie View
10-0267 Dive Xtras, Inc. Mr. Ben McGeever View
10-0194 Alaska Air Group, Inc. Mr. Mike Tobin View
10-0207 Airgas SAFECOR Mr. Jon Anderson View
11-0044 O2 Concepts, LLC Ms. Kathryn G. Forgione View
10-0021 Ohio State Highway Patrol Major Christopher K. Minter View
10-0155 DuPont Company Mr. Randolph Martin View
09-0084 Syncro Medical Innovations, Inc. Mr. Lalit Sabramanian View
10-0212 Thunderbird Cylinder, Inc. Mr. Fred Nachman View
11-0013 Transportation Management Group, Inc. Mr. John M. Domutz View
11-0019 Kajuligan Corporation Mr. Clifford Croft View
10-0254 Department of California Highway Patrol Captain Steve Dowling View
11-0022 Clean Venture, Inc. Mr. Roy H. Swartz View
11-0025 Securaplane Technologies, Inc. Mr. Rod Iverson View
11-0030 Baker Petrolite Corporation Mr. Aubrey Campbell View
PI-10-0016 City of Glendale Water & Power Steven G. Lins View
11-0017 Currie Associates, Inc. Mr. John V. Currie View
PI-10-0009 Pacific Gas and Electric Company Glen Carter View
PI-10-0008 Enbridge Offshore Pipelines (UTOS) L.L.C. Gregg Johnson View
10-0268 Cobham Mission Systems Division Mr. Brent Raiber View
10-0256 Clean Venture, Inc. Mr. Roy H. Swartz View
10-0169 Wiley Rein LLP Mr. George Kerchner View
11-0005 Suttons International Mr. David Brown View
11-0041 TEN-E Packaging Services, Inc. Mr. Robert J. Ten Eyck View
10-0266 Maxum West Mr. Brian Biancavilla View
11-0018 Aluminio No. 7 Ms. Isabel Martinez View
10-0261 Duke Energy Corporation Mr. Chuck Denny View
10-0080 Swatch Group Mr. Thomas Affolter View
10-0264 Liquid Robotics, Inc. Mr. Roger Hine View
11-0009 American Expedition Vehicles Mr. David Harriton View
10-0233 Veolia ES Technical Solutions, L.L.C Ms. Jennifer Eberle View
11-0031 Military Surface Deployment and Distribution Command Mr. Joseph P. Dugan View
10-0092 TEN-E Packaging Services, Inc. Mr. Robert J. Ten Eyck View
10-0270 Mr. James La Porte View
10-0262 Veolia ES Technical Solutions, L.L.C. Mr. Tom Baker Director View