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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
10-0234 Kelly Infinity Mr. Jeff Brown View
10-0222 Environmental Resource Center Ms. Rebecca Spaulding View
10-0253 AVOX Systems Inc. Mr. Joesph Contino View
PI-10-0017 Fulbright & Jaworsky L.L.P. Ms. Lisa Tonery View
10-0154 HAZMATPAC Mr. Donald H. Hausmann View
10-0208 Boyle Transportation Mr. Steven P. Norbeck, CDS View
PI-10-0025 Pierce Atwood LLP Mr. Randall S. Rich View
10-0219 Thompson Tank Inc. Mr. David Thompson View
10-0237 Avon Products Inc. Mr. Kevin Gannon View
10-0224 Corrigan Consulting, Inc. Mr. Wendell Honeycutt View
10-0241 Oxus, Inc. Mrs. Joan Rolwing View
10-0214 DGM USA Atlanta Mr. Jim Shimko View
10-0027 Federal Motor Carrier Safety Administration Mr. Joseph J. Evans View
10-0246 W.E. Train Consulting Mr. W. Eugene Sanders View
10-0179 Washington State Public Health Laboratories Mr. Chuck Talburt View
10-0220 McLane Company, Inc. Mr. John C. Anderson View
10-0232 URS Corporation Ms. Erin Jarman View
10-0185 FedEx Custom Critical Ms. Kellie Toth 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
09-0296 Mansfield Consultants HK Ltd. Mr. Jeffrey Mansfield View
10-0210 Cryofab, Inc. Mr. Greg Grillo 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
10-0201 Ford Motor Company Mr. Grant Haves View
09-0111 Carroll Welding Supply Mr. Wood Smith View
10-0200 Hazmat - CDMAT Mr. Harry Woods View
10-0145 KLM Royal Dutch Airlines Mr. Michael van der Velde View
10-0062 Air Liquide America Specialty Gases LLC Mr. Ralph Diaz View
10-0036 Dangerous Goods Declaration, Inc., and DGD Transport, Inc. Mr. Luis Lopez View
10-0168 Serenity Packaging Corporation Mr. Jerry Loza View
10-0215 Pimpelmees 3 Mr. Gilbert de Chauvigny de Blot View
10-0139 FedEx Freight Ms. Sandra Richesin View
10-0177 CSE Corporation Mr. Jeff Tocci View
PI-10-0001 B. Knight Natural Gas Services Mr. Michael H. Kyle View
10-0190 PCS Sales USA, Inc. Mr. Tracey G. Smith View
PI-10-0013 Pipestream, Inc Mr. Raymond N. Burke View
09-0306 Hazmat Resources, Inc. Mr. Danny Shelton View
10-0198 Smart-Hose Technologies Ms. Andrea Guevara View
10-0221 Metropolis Industries, LLC Mr. Kyle Long View
10-0186 URS Corporation Ms. Erin N. Jarman View
10-0048 Department of National Defence Captain E.M. Steele View
10-0126 Minnesota Department of Transportation Mr. Michael Ritchie View
10-0204 Bureau of Explosives Transportation Technology Center, Inc. Mr. Sam Chapman View
10-0187 Schlumberger Technology Corporation Mr. Paul Lezak View