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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
12-0095 Guerilla Air Mr. Sam Newman View
12-0174 Process Technology Optimization, Inc. Dr. Tilak Bommaraju View
12-0184 Ms. Shari Ann Fry View
12-0179 Dysol & MagChem Mr. Danny Gehlhausen View
12-0147 The Govmark Organization, Inc. Mr. Salvatore Messina View
12-0105 Arcet Cylinder Services Div. Mr. David Goff View
12-0150 Horizon Lines Mr. Clifford Bartley View
12-0128 SGS North America Mr. Terry M. Thompson View
12-0157 Perkins Coie Mr. Christopher J. Sutton View
12-0199 AirSep Corporation Mr. Richard W. Boerdner View
12-0081 Hazardous Material Packaging, Inc. Mr. Bill Holbrook Allflex View
12-0197 Chemplex Advance Materials, LLC Mr. Ed Vinson View
12-0201 Horizon Lines, LLC Mr. Cliff Bartley View
PI-11-0016 Atmos Energy Charles R. Yarbrough, II View
12-0092 PSEG Nuclear Mr. Ronny A. Olson View
12-0132 Hogan Lovells US LLP Mr. Kenneth M. Kastner View
12-0117 URS Corporation Ms. Erin N. Jarman View
12-0131 New Century Transportation, Inc. Ms. Donna Horn View
12-0107 North American Automotive Hazardous Materials Action Committee Mr. Dave Madsen View
12-0165 DRMS-VSE Mr. Sandy Clark View
PI-11-0014 Bose McKinney & Evans LLP Ms. Nikki Gray Shoultz, Esq. View
12-0014 Billco Manufacturing Ms. Kattie M. Barthlow View
12-0085 Brothers Group, Inc. Mr. Kenneth Kelton View
12-0162 Kiddie Fenwal Inc. Mr. Gil Walton View
12-0158 J.J. Keller & Associates, Inc. Mr. Tom Zielbell View
12-0100 Hilti North America Mr. Brandon Kapple View
PI-007-2012 Southern LNG Company LLC Mr. William G. Cope View
12-0062 Duke Energy Corporation Mr. Charles (Chuck) S. Denny View
12-0121 National Transportation Safety Board The Honorable Deborah A.P. Hersman View
12-0127 Veolia ES Technical Solutions, L.L.C. Ms. Jennifer Eberle View
12-0118 RemTec International Ms. Patricia Burns View
12-0047 Robertshaw Industrial Products Ms. Natalie Pike View
12-0113 Steris Mr. Kevin Corson View
12-0122 Ohio Transportation Department Mr. Tom Forbes View
12-0123 Jetstream of Houston, LLP Mr. Bill Slovak View
12-0136 Transportation Enforcement Division Public Utilities Commission of Ohio Mr. Carlisle Smith View
12-0119 Hazmat Service, Inc. Mr. Mark Phillip View
12-0151 Veolia ES Technical Solutions, L.L.C. Ms. Jennifer Eberle View
12-0149 Solvay Chemicals, Inc. Dr. Marc A. Feldman View
12-0139 Nebraska State Patrol Sergeant Brad Wagner View
12-0108 Wercs Professional Services Mr. Kevin Skerrett View
12-0126 Leland Limited, Inc. Ms. Dawn Rakita View
12-0067 Bechtel Corporation Ms. Yuliana S. Wu View
12-0129 View
12-0120 Greif, Inc., Rigid Industrial Packaging & Services, North America Mr. Jordan J. Brodsky View
12-0076 Hazardous Control Inc. Ms. Nina Ximena Artime View
12-0114 Ford Motor Company Mr. Grant Haves View
12-0094 Big Creek Media Mr. Nelson Lemmond View
12-0098 Smithers Pira Mr. Steve Dely View
12-0096 HMT Associates, L.L.C. Mr. E.A. Altemos View