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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
CHI-11-005 County of San Diego Tom Bosworth, Esq. View
CHI-11-002 County of San Diego Tom Bosworth View
PI-10-0018 Duke Energy Field Services, LP Mr. David Bohn View
PI-10-0022 Central Hudson Gas & Electric Corp. Mr. David W. Merte, P.E. View
11-0074 Currie Associates, Inc. Mr. Tom Ferguson View
11-0067 Airgas SAFECOR Mr. John Anderson View
11-0047 HMT Associates, L.L.C. Mr. Edward A. Altemos View
10-0252 The Dow Chemical Company Ms. Cherry Burke View
10-0116 NW Natural Mr. Neil Banman View
11-0007 The Law Offices of Paul D. Borghesani Paul D. Borghesani View
11-0002 Thompson Tank Inc. Mr. David Thompson View
CHI-11-004 Missouri Trucking Association Mr. Ronald D. Breau, CDS View
CHI-11-001 Missouri Trucking Association Ronald D. Breau View
09-0300 Sartorius Stedim Filters, Inc. Mr. José H. Braulio-Martinez View
11-0079 Mr. Roger W. Cooper View
PI-10-0015 Alta Mesa Services, LP Ms. Ronda Louderman View
10-0107 California National Guard U.S. Army Mr. Robert Morrow View
10-0066 FedEx Express Corporation Mr. David Littlejohn View
11-0070 DS Environmental Solutions Mr. Ricardo Guerra View
11-0021 Kajuligan Corporation Mr. Clifford Croft View
11-0038 Los Alamos National Laboratory Mr. Donald Thorp View
11-0072 AirSep Corporation Mr. Richard W. Boerdner View
11-0052 Honeywell Inc. Ms. Claire Matlon View
PI-11-0008 Northern Natural Gas Company Mr. Thomas Correll View
11-0078 Mr. Roger W. Cooper View
11-0046 Chart Industries Mr. Dan Bricker View
10-0125 Anitox Corporation Kurt Richardson, Ph.D. View
11-0058 Airspeed Press Mr. Steve Lindblom View
11-0027 The Council on Safe Transportation of Hazardous Articles, Inc. Mr. Thomas W. Ferguson View
10-0146 Clean Harbors Environmental Services, Inc. Mr. Anthony Cellucci View
11-0023 BioStorage Technologies Ms. Darcy Britt View
10-0171 AWE Mr. David A. Cocks View
10-0059 Bureau of Waste Prevention Massachusetts Department of Environmental Protection Mr. Bill Sirull Chief View
09-0211 ChemStation International Mr. Scott Meridith View
11-0035 Department of the Army Mr. Daniel A. Maham View
11-0051 Reckitt Benckiser, Inc. Mr. Richard Hessen View
11-0054 Environmental Management Ms. Misha Gonzales View
10-0259 Airgas SAFECOR. Mr. Jon Anderson View
11-0029 Department of the Army Mr. Daniel A. Maham View
11-0043 International Vessel Operators Dangerous Goods Association Mr. John V. Currie View
10-0267 Dive Xtras, Inc. Mr. Ben McGeever View
10-0194 Alaska Air Group, Inc. Mr. Mike Tobin View
09-0236 Department of State INL/A Mr. James A. Sherman View
10-0207 Airgas SAFECOR Mr. Jon Anderson View
11-0044 O2 Concepts, LLC Ms. Kathryn G. Forgione View
10-0021 Ohio State Highway Patrol Major Christopher K. Minter View
09-0084 Syncro Medical Innovations, Inc. Mr. Lalit Sabramanian View
10-0155 DuPont Company Mr. Randolph Martin View
10-0212 Thunderbird Cylinder, Inc. Mr. Fred Nachman View
11-0019 Kajuligan Corporation Mr. Clifford Croft View