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
13-0009 Bway Corporation Mr. Harold DePriest View
12-0254 Poly-Coat Systems, Inc. Ms. Suzanne Felix View
12-0216 Dyno Nobel Inc. Mr. J.D. Thomas View
13-0023 Chevron Phillips Chemical Company LP Mr. Jonathan VanScoyoc View
12-0271 Fred Guimond & Associates Mr. Fred Guimond View
13-0005 ATDynamics, Inc. Mr. Jeff Grossmann View
12-0238 Wers Professional Services Mr. Kevin Skerrett View
13-0008 Belshire Environmental Services, Inc. Mr. Larry Moothart View
12-0244 Airgas SAFECOR Mr. John Anderson View
12-0257 Conway Trucking Mr. Jeff Messer View
13-0016 American Ordnance LLC Mr. Charles McDowell View
12-0133R Autoliv Ogden Technical Center Mr. Dave Madsen View
13-0007 Wakefield Drilling & Blasting Mr. Darren Wakefield View
13-0014 Mr. Jason Spence View
13-0012 Amex Int'l, Inc. Mr. Arlee Mueller View
12-0260 TEN-E Packaging Services, Inc. Mr. Robert J. Ten Eyck View
13-0034 Labelmaster Services Mr. Robert Richard    View
13-0021 DHS – Transportation Security Administration Mr. William B. Thomas View
12-0235 Ms. Sandra Harding View
12-0211 HAZMATEAM Mr. Paul Dambek View
12-0250 Southeast Testing & Engineering Mr. Charles Radev View
12-0253 Chevron Phillips Chemical Co. LP Mr. Joel T. Robertson View
12-0265 Scopelitis, Garvin, Light, Hanson & Feary, P.C. Mr. Timothy Wiseman View
13-0006 Baker Hughes Mr. Aubrey R. Campbell View
12-0193 HAZ-MAT Transportation Services Mr. Jack Peters View
12-0203 Minnesota Department of Agriculture Mr. Ed Kaiser View
12-0268 Koppers Inc. Ms. Erin S. Murray View
12-0204 Newell Rubbermaid (Division of Sanford LLP) Mr. Chip Robison View
12-0175 International Union UAW Andrew Comai View
CHI-12-0175 International Union UAW Andrew Comai View
12-0261 Vasco Data Security NV Mr. Marc Covens View
12-0240 Department of Energy Mr. Stephen C. O'Connor View
12-0269 Posinelli Shughart Mr. Barton Day View
12-0188 Enservco Mr. Don Custer View
12-0246 AWP, Inc. Mr. Eric A. Hulme View
12-0251 Resistacap Energy Products Mr. Davy Hicks View
12-0220 Mr. Aaron Dills View
12-0266 Austin Power Company Mr. Thomas H. Snyder View
12-0194 DuPont Company Mr. Randolph Martin View
12-0264 Walker Group Holdings Transportation Tank Companies A Unit of Wabash National Mr. John F. Cannon View
12-0248 Northland Services, Inc. Mr. Scott McElhoe View
12-0230 Boreal Aviation, Inc. Mr. Bob Henning View
12-0138 Southeast Testing and Engineering Mr. Charles Radev View
12-0256 The Rechargeable Battery Association Mr. George A. Kerchner PRBA View
12-0252 CHART-SeQual Technologies, Inc. Mr. Ben Kadrlik View
12-0242 NK CO., LTD Mr. Hyun-Joon Ji View
12-0152 Curran International Mr. Chris Gomez View
11-0282R Ms. Kathy S. Gentry View
12-0245 VBOX Inc. Mr. Andy Linn View
PI-12-0006 Interstate Storage and Pipe Line Corporation Michelle Denault View