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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
15-0087 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
15-0038 Hazardous Materials Consultant Mr. Mark B. Hawk View
15-0001 FIBA Technologies, Inc Mr. Christopher Adams View
15-0025 Arizona Department of Public Safety Officer Daniel Voelker View
15-0011 CTC Certified Training Company Mr. Darrell K. Garton View
15-0066 Chesapeake Fire Department Mr. Simone J. Gulisano View
14-0143 Military Ocean Terminal Concord Mr. David Arange View
15-0014 U.S. Department of Energy Mr. Dennis Claussen View
PI-14-0016 Northern Utilities / Unitil Corporation Mr. Christopher J. LeBlanc View
14-0227 FedEx Express Mr. Marvin Sudduth View
15-0057 Clean Pack Training and Development Mr. Kevin S. Young View
14-0229 The Chlorine Institute Ms. Robyn Kinsley View
14-0169 A.S. Trust & Holdings, Inc. Mr. Richard Maruya View
14-0175 Linde Mr. John P. Smith PE View
14-0164 PCS Sales (USA), Inc. Mr. Tracey Smith View
14-0190 Pioneer Tank Lines, Inc. Mr. Larry Nielsen View
14-0135 Western Refining Mr. Victor Garcia View
14-0212 Product Regulatory Services Mr. Robert Miller View
14-0218 Maxxsonics Mr. Ken Eldridge View
PI-14-0019 Freeport LNG Mr. John A. Jacobi View
PI-15-0002 Wacker Polysilicon North America Mr. Jeremy Copeland View
PI-15-0001 EnVen Energy Ventures Mr. Robert Ellis View
14-0195 The Clorox Company Mr. Maurice C. Carson View
14-0201 ESCI EnviroServices, Inc Mr. Steven M. Lichten View
14-0196 Lamb Fuels, Inc. Mr. Jeff Lisowski View
14-0182 Reagent Chemical Mr. Robert Dritschel View
14-0177 American Marine Express Mr. Ramdy Wheaton View
14-0244 FSA Tech Services Mr. Gustavo Navar View
14-0208 Washington State Department of Health Mr. Chuck Talburt View
14-0147 Gayston Corporation Mr. Christopher A. Cornelius View
14-0222 Enterprise Products Mr. Christopher Scavone View
15-0023 Institute of Makers of Explosives Ms. Cynthia Hilton View
14-0205 RMS Interests, LLC Ms. Robin Smith View
15-0016 American Airlines Mr. Michel A. Wentz View