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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
09-0175 California Department of Fish and Game Mr. Charles R. Todd View
09-0116 Logistics OMG Americas, Inc. Mr. Patrick Foster View
09-0133R Total Energy Jennifer D. Janelle, Esq. View
09-0153 Layne Christensen Company Safety and Environmental Health Sciences Ms. Rhonda Heltzel View
09-0157 Hibrett Puratex Mr. John P. J. Madden View
09-0146 Westinghouse Electric Company Mr. Michael D. Alston View
09-0070 Thermo Fisher Scientific Mr. Gene Sanders View
09-0043 Otto Environmental Systems Mr. Rob Ellis View
09-0020 Horizon Lines, LLC Mr. Cliff Bartley View
09-0168 Baker Hughes Mr. Aubrey R. Campbell View
09-0147 AP Training, Inc. Mr. Hank Baird View
PI-09-0014 View
PI-09-0015 View
09-0166 Georgia Department of Public Safety Capt. Bruce Bugg View
09-0018 Bioject, Inc. Mr. David Stark View
09-0154 Stresau Laboratory, Inc. Mr. Richard Hoff View
09-0015 MDM Ltd. & Black Mag Industries Mr. Craig M. Sanborn View
PI-09-0012 WestPac Pipelines Mr. Adam F. Kovacs View
08-0218R First Alert BRK Brands, Inc. Mr. Brian J. Strasma View
PI-09-0021 New Mexico Public Regulation Commission Mr. Joe M. Johnson View
09-0143 Wiley Rein LLP Mr. George Kerchner View
09-0148 Mr. Peter Collins U.S. Department of Justice Federal Bureau of Prisons View
09-0122 Mr. Bill Lewis YRC Reimer View
09-0155 Inogen, Inc. Mr. Matt Scribner View
09-0144 Cytec Industries Stamford Hazards Lab Mr. Mark Ryan View
09-0156 PSC Environmental Services, LLC Mr. James V. Levitz View
PI-09-0007 Federal Energy Regulatory Commission Mr. Jeff C. Wright View
PI-09-0008 Kansas Corporation Commission Mr. Leo M. Haynos View
09-0124 Parsons Corporation Newport Chemical Depot NECDF Mr. Lawrence S. Thompson View
09-0145 Mr. James La Porte View
08-0181 Van Duzer Consulting Services Mr. Robert Van Duzer View
09-0067 Cabot Microelectronics Mr. Michael Trembley View
PI-09-0011 Interstate Natural Gas Association of America Mr. Terry D. Boss View
08-0158 Toppenish Community Hospital Carolyn Arms, MT(ASCP) View
PI-09-0010 Viridis Clean Energy Group Luong Nguyen View
PI-09-0001 Bracewell & Giuliani LLP George H. Williams, Jr. View
PI-09-0002 CDX Gas Mr. Greg Schrab View
09-0140 DGM Consulting Resources Mr. Jim Shinko View
09-0138 Godfrey & Kahn, S.C. Mr. Douglas M. Poland View
09-0011 Association of Clinical Research Professionals Mr. David Vulcano View
09-0149 Energy Solutions Mr. James H. Portsmouth View
07-0077 UPS Aircraft Maintenance Hangar Mr. Robert A. Stewart View
09-0115 North Carolina State Highway Patrol Trooper K.S. Herring View
09-0094 Roche Molecular Systems, Inc. Ms. Julie Park View
PI-09-0004 Enstar Natural Gas Company Mr. David W. Bredin View
09-0050 Hagemeyer North America Mr. Bill McDonald View
09-0139 Mr. Thomas Leech View
09-0108 Environmental Outsource, Inc. Mr. Andy Coyne View
PI-09-0009 Marathon Pipe Line L.L.C. Mr. Richard A. Abraham View
PI-09-0003 Enbridge Energy Partners, L.P. Ms. Denise Hamsher View