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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-96-022 Division Of Public Utilities and Carriers James J. Malachowski View
98-0340 Fireworks Mfg. Co Inc. Mr. Ronald C. Snyder View
99-0044 Fire Star Electric Match Mr. Jerry F. Dyben View
98-0366 Aero Tech Consumer Aerospace Mr. Gary C. Rosenfield View
99-0108 PATTON BOGGS LLP Ms. Carolina L. Mederos View
PI-99-003 Montgomery & Andrews Brett Olsen View
99-0048 Georgia Public Service Commission Captain Bruce Bugg View
PI-99-0101 Health, Safety, Environmental Quality & Regulatory Affairs Baker Petrolite Corporation Mr. Brian Friedman View
99-0081 Eastman Chemical Company Ms. Julie Brown View
99-0055 Suburban Propane Ms. Barbara J. Verdon View
99-0103 Department of the Army Mr. Thomas S. Smith View
99-0056 Radian International Mr. Andrew N. Romach View
99-0082 Defense Logistics Agency Mr. James 0. Rimel, St. View
99-0062 Mr. C. Vleugels View
99-0039 BP Oil Company Mr. J. J. Quandt View
99-0072 Kinsbursky Brothers Inc. Mr. Paul D. Johnson View
99-0061 Rossborough Manufacturing Co. Mr. Richard S. Varga View
98-0315 S.C. State Transport Police Corporal W.T. Rucker View
99-0025 Industrial Consulting Services Mr. Randy L. Holloway View
98-0268 Rocketflite Mr. Greg Dyben View
99-0003 Wright's Trucking & Harvesting Mr. Kent C. Wright View
99-0070 Delphi Automotive Systems Mr. Dave McCullough View
CHI-99-002 Menominee Indian Tribe of Wisconsin (see December 5, 2000 correction) Frank A. McLellan View
99-0069 Westinghouse Savannah River Site Ms. Carrie Ramsey View
98-0276 Special Police Officer Mr. Mel vonSoosten View
99-0068 BWX Technologies, Inc. Mr. John Krueger View
99-0074 HMT Associates Mr. E.A. Altemos View
99-0042 National Technical Systems Mr. Steve Farrar View
99-0050 Department of Transportation Mr. David 0. Sucha View
98-0383 Radian International Mr. Andrew N. Romach View
99-0060 Danzas S.P.A Mr. Carlo De Mercurio View
99-0026 Sakai Trading New York Inc. Mr. Y. Goto View
99-0077 American Freightways Mr. Ken Chambers View
99-0049 Navieras NPR, Inc. Ms. Myriam Rivera View
99-0029 Angus Chemical Company Lloyd H. Shanks View
98-0338 Aristech Chemical Corporation Mr. Michael D. Alston View
99-0037 Allegheny Airlines, Inc Mr. Wayne S. Lester View
99-0058 Great Lakes Chemical Corporation Mr. Robert Monteith View
99-0005 Package Research Laboratories Ms. Sue E. Pelletier-Bruno View
98-0326 Myers Industries, Inc. Ms. Barb Germano View
98-0345 Neal Langerman, Ph.D. View
99-0051 Southwest Research Institute Mr. Robert M. Valdez View
99-0053 Javelin Maintenance Support Center Mr. Bunker Hill View
98-0349 Monsanto Company Mr. William J. Briner View
99-0033 Fine Metals Ms. Christy Schwartz View
99-0009 New York State Department of Environmental Conservation Alan G. Woodard, PhD View
98-0378 Hilti, Inc. Mr. Marlyn Boyce View
99-0040 Department of California Highway Mr. Paul Horgan View
98-0330 Mainstream Engineering Corp. Mr. Lawrence R. Grzyll View
98-0316 Radian International Mr. Andrew N. Romach View