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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
12-0033 Freehold Cartage, Inc. Mr. J. Chip Brackett View
11-0221 Mr. Denis Jacques View
12-0060 Bombardier Aerospace Mr. Jeff Christafore View
12-0013 GeoDynamics Mr. Rick Chewning View
11-0294 Sea-Land Chemical Co. Mr. Kerry McMahon View
11-0003 S.E. McDonough & Associates, Inc. Ms. Susan E. McDounough View
12-0039 Caterpillar, Inc. Mr. Jerry A. Shipman En View
11-0310 Dannemiller Associates, Inc. Mr. Larry Dannemiller View
12-0064 Boyle Transportation Mr. Rick Araniz 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
11-0189R Mr. W. Eugene Sanders III W.E. Train Consulting View
12-0037 Naval Ordnance Safety and Security Activity Mrs. Karen Bonnin View
11-0302 Navarro Research and Engineering, Inc. Mr. David Wilson View
11-0291 Environmental Management, Inc. Jamie Newton View
12-0028 Waste and Compliance Management, Inc. Mr. Eric Smith View
12-0035 Winchester Ammunition Ms. Laura Hamilton View
11-0289 CH2MHILL Plateau Remediation Mr. Chris Backus View
11-0170 Orica USA, Inc. Ms. Lisa Nitschke View
11-0272 Safetech Mr. Robert Holley View
12-0002 Mr. Henry Wake Huffman View
12-0029 Colorcon No Tox Products Mr. Tim Jamison View
12-0018 United Parcel Service (UPS) Mr. Bob Cogen View
12-0055 J. J. Keller & Associates, Inc. Mr. Tom Ziebell Sr. View
11-0304 Dangerous Goods Transport Consulting, Inc. Mr. Frits Wybenga View
12-0052 Doughty & Carson, PLLC Mr. Oliver D. Adams Hodges View
12-0006 Lighter Association, Inc. Mr. David H. Baker View
11-0198 Landstar Transportation Logistics, Inc. Mr. Wes Pace View
11-0276 Mr. Lawrence W. Bierlein View
11-0217 View
11-0299 Mr. Paul J. Dambek     View
11-0121 Thompson Tank, Inc. Mr. David Thompson View
12-0032 MT Associates, L.L.C. Mr. E. A. Altemos View
11-0297 Linde Gas North America, LLC Mr. Guy Dalton    View
12-0075 Broward Fire Equipment and Service Inc. Mr. John A. Gioseffi View
12-0020 Federal Railroad Administration Mr. Dennis Campbell View
12-0021 Hazardous Control, Inc. Ms. Mabel Natalia Perez View
12-0023 View
11-0314 BioStorage Technologies Ms. Darcy Britt View
11-0274 Department of the Army Ms. Sarah Gedrich View
PI-11-0012 ONEOK NGL Pipeline. L.P. Mr. Wesley Christensen View
12-0011 Briggs and Stratton Corporation Mr. Don Pucci View
PI-11-0011 Hess LNG Mr. Leon A. Bowdoin. Jr. View
12-0003 Veolia ES Technical Solutions, L.L.C. Mr. Tom Baker View
12-0008 Caterpillar, Inc. Mr. Shae Birkey View
12-0012 Britton & Associates Attorneys at Law Mr. Shannon M. Trevithick View
11-0260 W.E. Train Consulting Mr. Gene Sanders View
11-0284 Northern California Fire Mechanics Association Mr. Frank Drayton View