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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
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
09-0123 HazMat Resoureces, Inc. Mr. Daniel G. Shelton View
08-0191R Magna Corporation Mr. Devon Schwalm View
09-0113 Murphy Industries Ms. Alecia Rice View
09-0119 Advance Asymmetrics, Inc. Mr. Lawrence D. Rutledge View
09-0105 ShipMate, Inc. Mr. Steven Charles Hunt View
09-0099 Oklahoma Historical Society Mr. Jim Lee View
09-0071 Oncology Supply Company Mr. Brad King Regulatory View
09-0110 FedEx Express Mr. Roy A. Parker, Ph. D. View
09-0035 Rohm and Haas Chemicals Mr. Vitaly Volfson View
09-0058 Thermo Fisher Scientific, Customer Channels Group Mr. Gene Sanders View
09-0127 Saint-Gobain Crystals Mr. Jeffrey L. Kennedy View
09-0097 Moeller Marine Products, Inc. Mr. Earnie Cook View
09-0061 Thompson Hine LLP Mr. David M. Schwartz View
PI-09-0013 View
09-0078 Kasi Infrared Corporation Mr. Thomas Allen View
09-0080 HMT Associates, LLC Mr. E.A. Altemos View
09-0085 Cell-Con, Inc. Mr. Steve Fricker View
08-0255 Tyco Safety Products Mr. Richard Seaburg View
09-0059 All Star Corrugated Ms. LaDonna Anthony View
09-0125 Association of American Railroads Mr. Robert E. Fronczak View
09-0114 TRG Inc. Mr. Robert E. Sever View
08-0220 URS Corporation Ms. Erin N. Jarman View
09-0049 Thermo Fisher Scientific Mr. John G. Mayfield View
09-0077 Crown Technology, Inc. Mr. Jeff Buckner View
09-0086 Ready Care Industries Mr. Aaron Yarnell View
09-0102 Inmark, Inc. Mr. Junius Johnson View
09-0068 Scopelitis, Garvin, Light, Hanson & Ferry Mr. Timothy W. Wiseman View
09-0066 URS Corporation Mr. Andrew Romach View
09-0047 FedEx Express Mr. Marvin A. Sudduth View
09-0081 Petronio Shoe Products Corporation Mr. Donald Rinaldi View
09-0054 Ricca Chemical Company LLC Mr. Loren K. Lowry View
09-0062 Container-Quinn Testing Laboratories, Inc. Mr. Stephen C. Powell View
09-0069 Thermo Fisher Scientific Mr. Gene Sanders View
09-0060 FuelTool, LLC Mr. Michael McAvey View
09-0022 NASA Wallops Flight Facility Mr. Ernest Cornwell View
09-0013 Clean Harbors Environmental Services, Inc. Mr. Anthony P. Cellucci View