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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
10-0242 URS Corporation Ms. Erin N. Jarman View
10-0182 J.J. Keller & Associates, Inc. Mr. Thomas Ziebell View
10-0122 Energy Solutions Ms. Merrie Schilperoort View
10-0163 SeQual Technologies, Inc. Ms. Pamela J. Jackson View
10-0244 Ashland, Inc. Mr. Gregory S. Phillips View
10-0015 Defense Ammunition Center Ms. Vickie A. Lewis View
10-0188 American Veterinary Medical Association Ms. Kristi Henderson View
09-0264 Kelly Aerospace Mr. Mark Mertes View
10-0040 University of Wisconsin Radiation Calibration Laboratory Ms. Wendy S. Kennan View
11-0001 NYC-DEP Mr. Mohamed Abdel Aal View
10-0265 Minnesota Department of Transportation Mr. Michael Ritchie View
10-0238R URS Corporation Ms. Erin Jarman View
09-0151 Solstice Neurosciences Mr. David Schaper View
09-0276 JJ Keller Mr. Leonard Satkowski View
10-0019R Mr. John Cox View
10-0249 Manager Cytec Industries, Inc. Mr. Charles Schreier View
10-0226 NACA Logistics (USA) Inc. dba Vanguard Logistics Mr. Eric Fischer View
10-0205 U. S. Department of Energy Ms. Anjali Shaykher Zutshi View
10-0183 Air Liquide America Specialty Gases LLC Mr. Ralph Diaz View
10-0159 Sandia National Laboratories Robert Rivera and Monica Ruiz View
10-0253 AVOX Systems Inc. Mr. Joesph Contino View
10-0234 Kelly Infinity Mr. Jeff Brown View
10-0222 Environmental Resource Center Ms. Rebecca Spaulding View
10-0154 HAZMATPAC Mr. Donald H. Hausmann View
PI-10-0017 Fulbright & Jaworsky L.L.P. Ms. Lisa Tonery View
10-0224 Corrigan Consulting, Inc. Mr. Wendell Honeycutt View
10-0219 Thompson Tank Inc. Mr. David Thompson View
10-0208 Boyle Transportation Mr. Steven P. Norbeck, CDS View
PI-10-0025 Pierce Atwood LLP Mr. Randall S. Rich View
10-0237 Avon Products Inc. Mr. Kevin Gannon View
10-0246 W.E. Train Consulting Mr. W. Eugene Sanders View
10-0214 DGM USA Atlanta Mr. Jim Shimko View
10-0179 Washington State Public Health Laboratories Mr. Chuck Talburt View
10-0027 Federal Motor Carrier Safety Administration Mr. Joseph J. Evans View
10-0241 Oxus, Inc. Mrs. Joan Rolwing View
10-0185 FedEx Custom Critical Ms. Kellie Toth View
10-0232 URS Corporation Ms. Erin Jarman View
10-0220 McLane Company, Inc. Mr. John C. Anderson View
10-0211 CYTEC Industries, Inc. Mr. Andrew Bethmann View
10-0206 Iowa Renewable Fuels Association Mr. Monte Shaw View
10-0175 HQDA G-3/5/7 DAMO-SSD Mr. Steve Carey View
10-0210 Cryofab, Inc. Mr. Greg Grillo View
09-0296 Mansfield Consultants HK Ltd. Mr. Jeffrey Mansfield View
10-0238 URS Corporation Ms. Erin Jarman View
PI-10-023 Baker Botts L.L.P. The Warner Bruce F. Kiely View
10-0133 American Ordnance LLC Iowa Army Ammunition Plant T. Bradley Vance View
10-0153 Public Health, Seattle and King County Mr. William Perry View
10-0130 Syngenta Mr. Eric Kelly View
10-0170 Energy Solutions, Inc. Ms. Merrie Schilperoort View
10-0200 Hazmat - CDMAT Mr. Harry Woods View