USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

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-73-0110 Public Works Department Ronald N. Hutton View
PI-73-0109 Corrosion Associates, Inc Mr. William C. Doll View
PI-73-011 Perry Gas Department Russell W. Itschner View
PI-73-010 West Virginia Public Service Commission T. K. Spalding View
PI-73-0108 The Pipe Line Development Company Mr. Ronald D. Gardner View
PI-73-0107 Mrs. N. A. Samples View
PI-73-0106 West Virginia Public Service Commission Mr. T. K. Spalding View
PI-73-0103 Alan H. Smith Consulting Engineers, Inc. Mr. A. Roy Whitelock View
PI-73-008 Iowa Public Service Company Thomas Mitchell View
PI-73-009 West Virginia Public Service Commission T. K. Spalding View
PI-73-0102 The Pipe Line Development Company Mr. Edward B. Smith View
PI-73-007 Pennsylvania Public Utility Commission Jerry Rich View
PI-73-006 State of Louisiana Department of Justice Michael A. Duplantier View
PI-73-005 New Mexico State Corporation Commission John A. Elliott View
PI-73-0104 Williams Brothers Pipeline Company M. W. A. Elliott View
PI-73-004 Cathodic Protection Service E. P. Doremus, P. E View
PI-73-0101 Division of Pipeline Safety State of Nebraska Mr. Harley Minniear View
PI-73-0100 Cathodic Protection Service Mr. E. P. Doremus, P.E. View
PI-73-001 Jones, Givens, Brett, Gotcher & Doyle William J. Doyle, II View
PI-72-0120 View
PI-74-0156 Arizona Corporation Commission H. R. Garabrant View
PI-72-056 City of Alexandria Gas Department John E. Sanchez View
PI-72-0118 Sprague Meter Company Mr. Howard W. Berghegger View
PI-72-0114 Mr. and Mrs. Gerhard Roscher View
PI-72-055 Memo: Internal View
PI-72-054 Eastern Shore Natural Gas Company Howard E. Boller: View
PI-72-053 Pipe Line Service Company J. F. Pfrank View
PI-72-052 Dye Carbonic of California, Inc. C. Edward Wolfe View
PI-72-051 Columbia Gas Service Company Don T. Caffery View
PI-72-0115 Piedmont Natural Gas Company, Inc Mr. H. F. Cain View
PI-72-0116 Missouri Public Service Commission Mr. Jeremiah D. Finnegan View
PI-72-0117 View
PI-72-050 Piedmont Natural Gas Company, Inc. H. F. Cain View
PI-72-048 Florida Public Service Commission Charles H. Batten View
PI-72-049 NACE Accreditation No. 21 Charles Kirklen View
PI-72-045 Anderson, Greenwood & Company J. H. Jordan View
PI-72-044 Arkansas Public Service Commission Benjamin C. McMinn View
PI-72-043 ANSI Standards Committee B16 Robert V. Warrick View
PI-72-042 Pan American Engineers R. D. Hodges View
PI-72-046 Equitable Gas Charles M. Rutter, Jr. View
PI-72-041 Texas Eastern Transmission Corporation Joseph Sallak View
PI-72-0113 City of Kansas City Mr. Donald E. Martin View
PI-72-0112 Honorable Robert Dole View
PI-72-039 Maryland Public Service Commission Charles C. Constantine View
PI-72-059 Zapata Pipeline Technology, Inc. T.J. Hayes, Jr. View
PI-72-058 Sun Pipe Line Company M. L. Sneed, P.E. View
PI-72-0111 Corrosion Engineering Mr. Henry F. Galka View
PI-72-038 Memo: Internal View
PI-72-037 Kerotest Manufacturing Corp Alban T. Russell View
PI-72-036 Florida Public Service Commission Charles H. Batten View