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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
11-0199 Trimac Management Services Mr. Len Comtois View
11-0293 Con-Way Freight Mr. Michael Gardner View
12-0071 Industrial Packaging Alliance of North America Mr. John McQuaid View
PI-12-0003 Public Utilities Commission of Nevada Mr. Donald Lomoljo View
PI-12-0001 American Midstream Mr. Kendall Lanningham View
11-0297R Linde Gas North America, LLC Mr. Guy Dalton View
12-0051 United Parcel Service Mr. Samuel Elkind View
11-0172 Wiley Rein, LLP Mr. George Kerchner View
12-0073 TEN-E Packaging Service, Inc. Mr. Robert J. Ten Eyck View
12-0030 U.S. Department of Defense, Attn: AMSSD-SA Mr. Elias V. Cantu View
12-0007 Lighter Association, Inc. Mr. David H. Baker View
12-0065 Chart Inc. Mr. Steve Therneau View
11-0113 Council on Safe Transport of Hazardous Articles, Inc. Mr. Thomas W. Ferguson View
11-0288 Diamon-Fusion International, Inc. Ms. Ana Zax View
12-0004 Regulatory Resources, Inc. Mr. Wade Winters View
12-0101 Somero Enterprises, Inc. Ms. Karen Massicotte View
12-0056 MD Packaging Solutions LLC Mr. Dan Dengler View
12-0061 David L. McLamb, Inc. Mr. David L. McLamb View
12-0031 Wiley Rein LLP Mr. George Kerchner View
12-0053 Blue Sky Technologies Mr. Charley Simpson View
12-0068 Argonne National Laboratory Mr. Lee Stevens View
12-0059 Mr. William Briner View
12-0038 Mr. Charles E. Tudor View
10-0251 PBI Technology, Inc. Mr. Paul Bess View
12-0044 Council on the Safe Transportation of Hazardous Articles, Inc. Mr. Tom Ferguson View
11-0090 Hazmat Compliance & Transportation Mr. Kevin Gannon View
12-0005 Global Passive Safety System Ltd. Mr. Andy Abrams View
10-0236 Mr. Peter Lowe View
10-0095 Mr. Bill Briner View
11-0146 Mr. Thomas W. Ferguson The Council on Safe Transportation of Hazardous Articles, Inc. View
11-0252 Diamon-Fusion International, Inc. Ms. Ana Zax View
11-0296 Washington Closure Hanford, LLC Mr. Robinson E. Fillmore View
12-0054 DuPont Global Logistics Mr. Kevin M. Greene View
12-0045 DG Advisor, LLC Mr. Ben Barrett View
12-0080 Christensen Company Ms. Rhonda Heltzel View
12-0033 Freehold Cartage, Inc. Mr. J. Chip Brackett View
11-0158 Corrosion Testing Laboratories, Inc. Mr. Bradley D. Krantz View
11-0221 Mr. Denis Jacques View
12-0060 Bombardier Aerospace Mr. Jeff Christafore View
11-0003 S.E. McDonough & Associates, Inc. Ms. Susan E. McDounough View
12-0013 GeoDynamics Mr. Rick Chewning View
11-0294 Sea-Land Chemical Co. Mr. Kerry McMahon View
12-0039 Caterpillar, Inc. Mr. Jerry A. Shipman En View
12-0064 Boyle Transportation Mr. Rick Araniz View
11-0310 Dannemiller Associates, Inc. Mr. Larry Dannemiller View
12-0058 Sandia National Laboratories, New Mexico Mr. David Castillo View
12-0016 View
12-0034 Container-Quinn Testing Laboratories, Inc. A Division of Holmes Testing, Inc. Mr. Steven Powell View
11-0278 Thunderbird Cylinder Mr. Fred Nachman View
12-0037 Naval Ordnance Safety and Security Activity Mrs. Karen Bonnin View