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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
09-0120 Fleet Safety Services, Inc Mr. Gary LaBreck View
CHI-10-006 Potomac Strategy Associates Jerry W. Cox, Esq. View
10-0046 North Carolina State Highway Patrol Lt. D. R. Shackelford View
09-0249 Dangerous Goods United Airlines Ms. Nancy Finkenkeller View
08-0192 Titan Specialties, Ltd. Ms. Shelly Espinoza View
10-0074 REC Advanced Silicon Materials LLC Mr. Clint Peters View
09-0216 Ashtead Technology, Inc. Mr. Jason Miller View
10-0029 DG Advisor, LLC Mr. Ben Barrett DG Advisor, LLC View
10-0037 MST2 USCG Sector LA-LB, Facilities Branch Christopher H. Smith View
CHI-10-003 B.J. Alan Company William A. Weimer, Esq. View
09-0160 National Electrical Manufacturers Association Mr. Kyle Pitsor View
09-0271 Marine Spill Response Corporation Mr. Mike Sample View
09-0206 State of Utah Department of Environmental Quality Mr. Dane Finerfrock View
10-0003 Labconco Corporation Mr. Daniel Taylor View
PI-10-0020 Holland & Knight Ms. Dianne R. Phillips, Esq. View
10-0016 Entegris, Inc. Mr. Kevin Bevis View
10-0004 BP West Coast Products LLC Ms. Ana Wauthion-Melgar View
09-0270 The Metropolitan Water District of Southern California Mr. John E. Clark View
PI-09-0019 New Mexico Public Regulation Commission Mr. Joe M. Johnson View
10-0001 U.S. Department of Energy Ms. Dana Willaford View
10-0017 MGA Research Corporation Mr. Michael Greiner View
10-0011 Mr. Michael Coletta View
10-0097 Wal-Mart Stores, Inc. Mr. Mickey R. Dragash View
10-0033 Industrial Packaging Alliance of North America Mr. John McQuaid View
CHI-10-002 Wal-Mart Stores, Inc. Mickey R. Dragash View
10-0018 Symmetricon Ms. Susan Durr View
10-0030 Environmental Scientist URS Corporation Ms. Erin N. Jarmin View
PI-09-0022 Kansas Corporation Commission Mr. Leo M. Haynos View
09-0286 State of Wisconsin Department of Health Services Mr. Jason Hunt View
10-0014 Destileria Serrallés, Inc. Mr. Roberto Pantoja View
09-0255 Wiley Rein LLP Mr. George Kerchner View
09-0273 Dow Corning Corporation Mr. Stephen V. Moser View
10-0012 Detector Electronics Corporation Mr. Jon Varner View
09-0303 Electrochem Solutions Mr. Todd Sweetland View
09-0238 Mitsubishi International Corporation Ms. Lyn Russo View
09-0254 Nippon Cargo Airlines Co., Ltd. Narita International Airport Mr. Iwahiko Uehara View
09-0241 DHL Aviation Americas, Inc. M. Lourdes Navarro View
09-0207 USA 3000 Airlines Mr. William J. Hoffmann View
09-0221 The Council on Safe Transportation of Hazardous Articles, Inc. Mr. Tom Ferguson View
09-0289 Lincoln-Lancaster County Health Department City of Lincoln Nebraska Mr. Daniel N. King View
09-0272 Lufthansa - The Americas Mr. Hilmar Leng View
09-0299 SeraCare Life Sciences Mr. Colin Leavitt, Jr. View
10-0005 Mr. Frits Wybenga View
09-0267 ChemADVISOR, Inc. Mr. Kevin Lapp View
09-0044 Restek Corporation Mr. Erik Perrin View
09-0304 Bioxygen Distribution Corporation Mr. Kevin DelGaudio View
09-0307 Lovitz PSC Environmental Services, LLC Mr. James V. Lovitz View
09-0171 Carus Corporation Mr. Chithambarathanu Pillai View
09-0136 SJ Transportation Co., Inc. Mr. Christopher P. Prioli View
09-0265 Air Liquide America Specialty Gases LLC Mr. Ralph Diaz View