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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
12-0006 Interstate Storage and Pipe Line Corporation Ms. Michelle Denault View
12-0146 ADG Compliance Manager Mr. Bob Cogen View
12-0192 Windward Aviation, Inc. Mr. Don Shearer View
PI-12-0008 Associated Safety Consultants, Inc. Mr. Michael J. Frenzel View
12-0173 HMT Associates, L.L.C. Mr. E. A. Altemos View
12-0255 North America Regional Trainer Ms. Susan Numbers View
12-0239 ATMI, Inc. Mr. James McManus View
12-0259 Dangerous Goods Advisory Council Mr. Vaughn Arthur View
12-0236 Dynetek Industries Ltd. Mr. Stefan Frey View
12-0213 Senior Mechanical Engineer Mr. Mark Fazzio View
12-0185 Missouri Department of Natural Resources Ms. Kathy Flippin View
12-0170 Sandler, Travis & Rosenberg, P.A. Mr. Mark Ludwikowski View
12-0237 Total Petrochemicals & Refining USA, Inc. Ms. Karen Scheel View
12-0198 Pacific Scientific Energetic Materials Company Mr. Timothy S. Dillon View
12-0168 WR Grace Mr. Norm Stollberg View
12-0176 Georgia Fire Protection Mr. W.A. Andrews View
12-0181 Railroad Regulatory Safety Services Mr. Raymond Kasey View
12-0187 Olin Corporation/Winchester Division Ms. Laura Hamilton View
12-0208 Occidental Chemical Company Mr. Norman Dodson View
12-0215 Hazardous Materials Specialist Mr. Tom Forbes View
12-0189 Wirtgen America, Inc. Ms. Stephanie Dalton View
12-0207 Railroad Regulatory Safety Services Mr. Raymond Kasey View
12-0200 Events Air Cargo Mr. Vincent F. Staregowski View
12-0166 Thermo Fisher Scientific Mr. John G. Mayfield View
12-0229 Currie Associates, Inc. Ms. L'Gena Prevatt View
12-0206 Ammunition Surveillance Inspector Mr. David Arange View
12-0226 Groendyke Transport, Inc. Mr. Jerry Mahl View
12-0116 The Valspar Corporation Mr. Eric Barcaskey View
12-0145 HazMat Resources Inc. Danny Shelton View
12-0164 ARTA Group, Inc. Dr. Alex von Keitz View
12-0110 Akrochem Corporation Scott Fleming View
12-0209 K & P Trucking, Inc. Ms. Kathy McConnell View
12-0195 Philips Respironics Mr. Joseph E. Olsavsky View
12-0137 Data Domain, BRS Division of EMC Corporation Mr. Kendall Wilcox View
12-0186 URS Corporation Mr. Andy Romach View
12-0177 Homax Group, Inc. Mr. Eric Clifford View
12-0182 ChemPura Pools, Ltd. Mr. David Brady View
12-0183 Bureau of Explosives, TTC, Inc Mr. Paul Draper View
12-0155 Scopelitis, Garvin, Light, Hanson & Fears Mr. Timothy W. Wiseman, Esq. & Mr. Jeffrey S. Jackson, Esq. View
12-0180 Concorde Battery Mr. Steve Delmar View
12-0227 IQ Products Company Mr. P. Yohanne Gupta View
12-0223 Mr. John A Desharnais View
12-0160 Donovan Marine, Inc. Mr. Keith Mauer View
12-0202 NK CO., LTD Mr. Hyun-Joon Ji View
12-0169 LANXESS Corporation Ms. Cyndi Fink View
12-0172 Detector Electronics Corporation Mr. Lee R. Zwiefelhofer View
PI-12-0002 McAfee & Taft Chris A. Paul, Esq. View
12-0153 Autoliv ASP, Inc. Mr. Dave Madsen View
12-0133 Autoliv Ogden Technical Center Mr. Dave Madsen View
12-0167 FedEx Express Mr. David Littlejohn View