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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
10-0144 MAR COR PURIFICATION Mr. Rollie Weberg View
10-0073 Eastman Chemical Company Texas Operations Ms. Marilyn Williams View
10-0010 B&W Pantex, LLC Mr. Jesse Beyers View
11-0126 Sandia National Laboratories Mr. Michael W. Enghauser View
11-0165 Thermofisher Ms. Melissa Russell View
11-0213 AT&T Mr. Jim La Port View
08-0269 PDT Packaging, Design & Testing, LLC Mr. Chris Weigert View
11-0187 Greif Packaging LLC Mr. Peter R. Apostoluk View
10-0141 Triumvirate Environmental, Inc. Mr. John Menzigian View
11-0068 P&G Mr. Alvin J. Bernstein View
PI-11-0010 Gallagher Evelius & Jones LLP Ms. Alison S. F. Lambert View
11-0059 HazMat Resources Inc. Mr. Daniel G. Shelton View
11-0200 Wyle Laboratories Mr. Brian Coppock View
11-0229 Inogen, Inc. Mr. Matt Scribner View
11-0191 Carus Chemical Company Chithambarathanu G. Pillai, Ph.D. View
10-0052 Alliant Techsystems Inc. (ATK) Mr. Christopher J. Widman View
10-0082 Osram Sylvania Mr. John Fichera View
11-0205 AT&T Mr. Jim La Porte View
11-0050 Pira International Mr. M. David Brooks View
11-0164 UPS Mr. Samuel Elkind View
11-0188 Riceland Foods, Inc. Mr. Neil Washburn View
10-0225 HazMat Resources, Inc. Mr. Daniel G. Shelton View
11-0206 CH2MHill Mr. Chris Backus View
11-0227 Inmark Mr. Jay Johnson View
11-0166 Con-way Freight Ms. Marie Easley-Cook View
10-0077 Thunderbird Cylinder Mr. Fred A. Nachman View
11-0062 DuPont Company Mr. Randolph Martin View
11-0179 Hapag-Lloyd (America) Inc. Mr. Matt Krynski Director View
11-0171 Reynolds Transport Mr. Aaron Carr View
11-0055 Railroad Commission of Texas Mr. James Osterhaus View
11-0133 View
11-0160 Con-way Freight Ms. Marie Easley-Cook View
11-0162 Duke Energy Corporation Mr. Chuck Denny View
11-0175 NitroxFox LLC. Mr. John Fox View
11-0127 Veolia Environmental Services Ms. Jennifer Eberle View
11-0076 Con-way Freight Mr. Keith Jesse Powell View
10-0213 Thunderbird Cylinder, Inc Mr. Fred Nachman View
11-0163 International Radiation Safety Consulting, Inc. Mr. Sean Chapel View
11-0131 Flightpath Services, Inc. Mr. Douglas Svoboda View
11-0161 Young & Franklin Inc. Mr. Greg Michalowski View
11-0173 Department of the Army- SDDC Mr. Daniel A. Maham View
11-0061 Ventura Transfer Company Mr. Jim Cheney View
11-0135 Veolia Environmental Services Ms. Jennifer Eberle View
11-0145 Riceland Foods, Inc. Mr. Neil Washburn View
10-0134 Conax Florida Corporation Cobham Life Support Mr. Thanh Seybold View
11-0143 ICC Nexergy Mr. David Brongiel View
11-0040 U.S. Department of Energy Office of Packaging and Transportation Mr. James M. Shuler Manag View
11-0151 National Aquatic Service, Inc. Mr. Michael Druce View
11-0106 The Jet Companies Mr. Mark Ellery View
10-0257 Thompson Hine LLP Mr. Jason Tutrone View