USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

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
09-0229 Baker Petrolite Corporation Mr. Aubrey R. Campbell View
09-0188 Wiley Rein LLP Mr. George Kerchner View
PI-09-0018 View
CHI-09-001 Wal-Mart Stores, Inc. Thomas E. Evans View
10-0025 Wal-Mart Stores, Inc. Mr. Thomas E. Evans View
09-0210 A123 Systems Mr. C. Michael Hoff View
09-0197 Tennant Company Mr. Charlie Brandenberg View
09-0065 ACM Global Central Laboratory Ms. Lisa Fotheringham View
09-0185 Industrial Packaging Alliance of North America IPANA/SSCI Mr. John A. McQuaid View
09-0232 BP Products North America Ms. Becky Conn View
09-0222 FIBA Technologies, Inc. Mr. Christopher R. Adams View
09-0037 Thermo Fisher Scientific Mr. Gene Sanders View
09-0191 All-Pak Inc. Mr. Christian Prickett View
09-0200 Owen Compliance Services, Inc. Mr. David W. Boston View
09-0215 Mr. Steve Laughlin View
09-0224 URS Ms. Erin N. Jarman View
09-0182 GE Sensing & Inspection Technologies Mr. Tom Piggin View
09-0204 Applied Cleaning Technologies, Inc. Mr. Paul A. Ackermann View
09-0177 Worthington Cylinder Corporation Mr. Steven T. Gentry View
09-0189 The Jackson Laboratory-West Ms. Kristela Ramos View
09-0064 C & N Companies Mr. Jon Bjornstad View
09-0205 URS Corporation Ms. Erin N. Jarman View
09-0212 Horizon Hobby, Inc. Mr. Travis Morenz View
09-0152 Fort Wainwright Ammunition Supply Point Mr. William H. Orth III View
09-0121 Grafco, LLC Ms. Jan Cowles View
09-0176 Chemtran Services USA, Inc Mr. Randy Hill View
09-0201 Hazmat, Inc. Mr. Paul J. Dambek View
09-0192 Hazmat, Inc. Mr. Paul J. Dambek View
09-0187 Infotrac, Inc. Mr. Jason Kob View
09-0195 Certispec Services USA, Inc. Mr. David O. Jones View
09-0137 J.B. Hunt Transport, Inc. Mr. Jon Adams View
09-0046 Honeywell Ms. Claire Matlon Leader View
09-0030 Household Hazardous Waste Program Alameda County Mr. Bill Pollack View
09-0179 Union Tank Car Company Mr. Gary Alderson View
09-0190 Pacific Northwest National Laboratory Mr. Larry Stuhl View
09-0164 Cytec Industries Inc. Mr. Andrews Bethmann View
09-0142 Westinghouse Electric Company LLC Mr. Michael D. Alston View
PI-09-0017 View
PI-09-0016 View
09-0186 Oregon Health and Science University Ms. Debra A. Brickey View
09-0175 California Department of Fish and Game Mr. Charles R. Todd View
09-0116 Logistics OMG Americas, Inc. Mr. Patrick Foster View
09-0133R Total Energy Jennifer D. Janelle, Esq. View
09-0153 Layne Christensen Company Safety and Environmental Health Sciences Ms. Rhonda Heltzel View
09-0157 Hibrett Puratex Mr. John P. J. Madden View
09-0146 Westinghouse Electric Company Mr. Michael D. Alston View
09-0070 Thermo Fisher Scientific Mr. Gene Sanders View
09-0043 Otto Environmental Systems Mr. Rob Ellis View
09-0020 Horizon Lines, LLC Mr. Cliff Bartley View
09-0168 Baker Hughes Mr. Aubrey R. Campbell View