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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-89-026 Western Utility Company, Inc. Joe C. Hugo View
PI-89-025 Texas Gas Transmission Corporation Gayle Bodner View
PI-89-024 Hewlett-Packard Company James C. Powell View
PI-89-023 SkyVision Michael E. Henry View
PI-89-022 Minnesota Office of Pipeline Safety William Barbeau, Ronald Wiest View
PI-89-021 Looper, Reed, Ewing & McGraw Incorporated Douglas B. Wyatt View
PI-89-020 Mid-Continent Pipe Line Company H. L. Crawford, Jr. View
PI-89-018 Exxon Gas System, Inc. J. Keith McSorley View
PI-89-017 Clarke-Mobile Countries Gas District John E. Adams, Jr. View
PI-89-016 Looper, Reed, Ewing & McGraw, Incorporated Douglas B. Wyatt View
PI-89-014 Oklahoma Corporation Commission Dennis Fothergill View
PI-90-027 Eichhorn, Eichhorn & Link Douglas B. Stebbins View
PI-89-013 Public Service Commission of Nevada Jeffrey L. Maples View
PI-89-012 Memo: Internal View
PI-89-011 Memo: Internal View
PI-89-010 Colorado Public Utilities Commission Arnold H. Cook View
PI-89-009 Long Island Lighting Company Ellen Bardenhagen View
PI-89-006 Memo: Internal View
PI-89-005 Pennsylvania Public Utility Commission Williams E. Smeigh, Jr. View
CHI-89-001 National Tank Truck Carriers, Inc. Clifford J. Harvison View
PI-89-003 Montana-Dakota Utilities Company Tony J. Finneman View
PI-89-002 Arkla Energy Resources Paul G. Espinosa View
PI-89-001 PHMSA Alert Notice View
PI-88-005 U.S. House of Representatives Bill Archer View
PI-88-004 Memo: Internal View
PI-88-002 Texas Gas Association Mr. Harry E. Neel View
CHI-98-001 National Tank Truck Carriers, Inc. Clifford J. Harvison View
PI-88-003 Missouri Public Service Commission Mr. Dale W. Johansen View
PI-87-004 Koch Industries, Inc. Ronny C. Davenport View
PI-87-003 U.S. Department of Transportation L. M. Furrow View
PI-87-002 Public Utilities Commission Robert S. Stone View
CHI-87-004 Lawrence W. Bierlein, P.C. Gordon Rousseau View
CHI-87-003 Lawrence W. Bierlein, P.C. Gordon Rousseau View
PI-87-001 Westar Transmission Company Nabil S. Dia, P.E. View
PI-86-006 Mid-America Pipeline Co. R. E. Penderson View
PI-86-005 Memo: Internal View
PI-86-004 Public Service Commission E. Scott Smith View
PI-86-003 Florida Power & Light Company John M. Stokes View
PI-86-002 Memo: Internal View
PI-86-001 Georgia Public Service Commission Glynn Blanton View
PI-85-009 Montana-Dakota Utilities Company Tony J. Finneman View
PI-85-008 Simmons J. Barry & Associates Dan S. Ray View
PI-85-006 Petroleum Operations & Support Services, Inc. Walter S. Malinowski View
PI-85-005 Hydrocarbon Transportation, Inc. A. V. Spitser View
PI-85-0102 PRI Gasco, Inc. Mr. David Y. Morikawa View
PI-85-003 Memo: Internal View
PI-85-002 Missouri Public Service Commission Dale W. Johansen View
PI-85-001 INCA Lawrence Ogden View
PI-85-0101 Stretch, Lang, Weeks & Cardon Mr. James A. Ryan View
PI-85-011 Streich, Lang, Weeks & Cardon James A. Ryan View