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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
02-0149 Office of Hazardous Materials Enforcement Doug S. Smith View
02-0204 D&G Consulting, Inc Glen K. Wanczyk View
02-0210 Phil Vonderwell View
02-0211 Minnesota Department of Transportation, Office of Motor Carrier Services Michael Ritchie View
02-0228 PPL Technical Training Center Frederick A.Muthard View
02-0165 Eastern Isotopes, Inc. Jim Kostka View
02-0239 The Fertilizer Institute Pain Guffain View
02-0193 Bioject, Inc. Tom Brooks View
02-0143 Gebauer Company Ron Coleman View
02-0207 Paul Reamy View
02-0205 California International Chemical Co., Inc. Karen Lowell,Esq. View
02-0169 National Cargo Bureau, Inc. Captain Sam Rogers View
02-0220 Vaught Aircraft David Norton View
02-0196 BMW Group Christian Baierl View
02-0125 3M Company Ray Duzynski View
PI-02-0101 Public Utilities Commission of Ohio Edward M. Steele View
02-0184 Innergy Power Corporation Darrell Musick View
02-0198 Applied Biosystems David W. Olson View
02-0183 Exotherm Technology, Inc. Robert W.Stephens View
02-0180 AAPER Alcohol Linda Whitton View
02-0164 Spartanburg Stainless Products, Inc Scott Rosenberge View
02-0154 U. S. Department of Energy Kent Hancock View
02-0159 HMT Associates, L.L. E. A. Altemos View
02-0172 Packaging Corporation of America Robert M.Sweitzer View
02-0155 St. John's Health System Stephen A. Kemp View
02-0173 BAE Systems Michael S.Krupka View
02-0188 Raytheon Company Ted A. Rust View
02-0142 White House Sales Mark Frese View
02-0035 Smurfit-Stone Container Corporation Richard M.Thomas View
02-0352 Proco, Inc. Noel McKim View
02-0167 Corrugated Supplies Corporation Tony Senzel View
02-0162 Johnson Matthey, Inc. Bill Erickson View
02-0044 Zambelli Internationale Fireworks Mfg. Co. Inc. Ron Snyder View
02-0178 Environmental Resource Center Rebecca M. Spaulding View
02-0166 AFGO Laboratories, Inc. Dale D. Benincasa View
02-0177 Brenntag Mid-South, Inc. Fred E. Nichols View
02-0157 Gislason & Hunter LLP Gary W. Koch View
02-0133 gh Package/Product Testing & Consulting, Inc Bernhard Bieri, III View
02-0112 Hawks Logistics Steve E. Hawks View
02-0110 ExxonMobil Chemical Company, Intermediates, Synthetics Product Stewardship Ronald J. Stokes View
02-0179 URS Corporation Andrew N. Romach View
02-0073 AllTransPack, Inc. Hank Baird View
02-0096 Boeing Satellite Systems, Inc. Richard L. Walters View
02-0124 Inland Paperboard and Packaging, Inc John H. Rutherford View
01-0270 EM Science Mr. Andrew Parrella View
02-0163 Suburban Propane Michael G. Merrill View
02-0084 US Liquids of Georgia Solvent Division JoanVan Matre View
02-0148 gh Package & Product Testing and Consulting, Inc. H. Perry Hock View
02-0121 Thomas J. Leech, III View
02-0103 R+L Carriers Dana Probasco View