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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
15-0032 Air Liquide (USA) LLC Mr. Jerry Freeman View
15-0065 SOLARIS Mr. Keane Lao View
15-0015 FedEx Express Mr. Marvin Sudduth View
15-0080 Chemours Company FC, LLC Mr. Randolph Martin View
15-0053 Mr. Kevin Skerrett View
15-0049 Thompson Tank, Inc. Mr. David Thompson View
14-0238 Surface Deployment and distribution Command Mr. Marco Boasso View
15-0091 Ammunition Surveillance Division Mr. James Gibson View
15-0071 Professional Emergency Resource Services (PERS) Mr. Rick Heylmun View
14-0237 Textron Systems, Weapons & Sensor Systems Mr. James Baustert View
14-0157 Alaska Airlines Mr. Mike Tobin View
15-0034 Crowley Liner Service Mr. Michael Lesser View
15-0076 The Lane Construction Corporation Ms. Michele Jacobs View
14-0235 Trinity Containers, LLC Mr. Greg McRae View
15-0074 SGS North America, Inc. Mr. Jason Sherrier View
14-0246 Wiley Rein LLP Mr. George Kerchner View
15-0005 Traffic Stripes, LLC. Mr. Paul Anderson View
14-0178 South Carolina State Transport Police First Sergeant Dean Dill View
14-0146 Det-Tronics Mr. Lee Zwiefelhofer View
15-0098 United States Department of Interior Mr. Greg Lawler View
15-0048 Oak Harbor Freight Lines, Inc. Mr. Tom Mueller View
15-0042 Transport Canada, TDG Ms. Nida Chaudhary View
15-0078 Maryland Department of Environment Mr. Michael Polinski View
14-0248 R&S Compliance group, LLC. Mr. David Rivers View
15-0003 Tech Ord Mr. Ken Martinmaas View
15-0035 Hedrick, Gardner, Kincheloe & Garofalo, LLP Ms. Lindsey L. Smith View
15-0056 Regulatory Resources, Inc. Mr. W.A. Winters View
14-0242 Bureau of Radiation Protection Ms. Celia Rajkovich View
15-0051 Scientific Innovations, LLC Mr. Steve Foster View
15-0010 Hexagon Ragasco North America Inc. Mr. Jonas Berglund View
15-0061 Currie Associates, Inc. Ms. L'Gena Shaffer View
15-0069 Mr. Joseph Tsiyoni View
15-0028 Duke Energy Corporation Mr. Chuck Denny View
15-0087 Con-way Freight Ms. Marie Easley-Cook View
14-0216 Savethesituation Ms. Eva Glimsche View
15-0095 AECOM Ms. Erin Jarman View
15-0046 Dangerous Goods Department Mr. Sergio Bustamante M View
15-0036 U.S. Department of Energy Mr. Dennis Claussen View
15-0081 LabelMaster Services Mr. Robert Richard View
15-0050 URS Corporation Mr. Andrew Romach View
14-0138R Polytek Development Corp. Ms. Cynthia Salisbury View
15-0075 Dexsil Corporation Mr. Andrew Lynn View
15-0045 Northern Air Cargo Mr. Mark Smith View
14-0234 Club Assit, North America Ms. Shelley Elzer View
15-0013 Pinnacle Propane Mr. Kyle Sparks View
15-0004 LPS Industries Mr. Gary Flaherty View
14-0225 Dangerous Goods Advisory Council Mr. Delmer Billings View
15-0008 Recology San Francisco Mr. Billy Puk View
14-0217 Southwest Airlines Co. Mr. Ben Pritchett View
PI-14-0015 Legacy Reserves Operating LP Mr. Scott Bliss View