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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
PI-11-0011 Hess LNG Mr. Leon A. Bowdoin. Jr. View
12-0008 Caterpillar, Inc. Mr. Shae Birkey View
12-0011 Briggs and Stratton Corporation Mr. Don Pucci View
12-0003 Veolia ES Technical Solutions, L.L.C. Mr. Tom Baker View
12-0012 Britton & Associates Attorneys at Law Mr. Shannon M. Trevithick View
11-0260 W.E. Train Consulting Mr. Gene Sanders View
11-0284 Northern California Fire Mechanics Association Mr. Frank Drayton View
11-0212 View
11-0271 Eastman Chemical Co. Ms. Julie Brown View
11-0237 Chart, Inc. Mr. Steve Therneau View
12-0015 AT & T Inc. Mr. Jim La Porte View
11-0305 Public Utilities Commission of Ohio Mr. Carlisle Smith View
11-0311 Weatherford International Mr. Tim Redwine View
12-0009 Yokayo Biofuels Mr. Brian Eberly View
11-0246 Defense Ammunition Center Mr. Jeff Stretton View
11-0290 Department of the Army Ms. Sarah Gedrich View
12-0019 Council on the Safe Transportation of Hazardous Articles, Inc. Mr. Tom Ferguson View
11-0307 ICC Nexergy Mr. David Brongiel A View
11-0313 Patterson Companies, Inc. Mr. Robb Boros Patte View
11-0283 R & L Carriers, Inc. Mr. Gerald A. Krisa View
11-0226 Spec Ops Company Jason Romero View
11-0298 Public Utilities Commission of Ohio Transportation Department Compliance Division Mr. Tom Forbes View
11-0261 Mr. Aaron Hackman View
11-0270 Ferrellgas LP Mr. Jerry Swank View
11-0287 USA Shooting Mr. Robert K. Mitchell View
11-0144 Chart Industries, Inc. Mr. Marty Beyer View
11-0295 Precision Medical, Inc. Mr. Jim Parker View
10-0147 CVA, Inc. Mr. I. Keith Hall View
11-0142 Patterson Companies, Inc. Mr. Robb Boros View
11-0275 American Coatings Association, Inc. Ms. Heidi K. McAuliffe, Esq. View
11-0259 ENPAC, LLC Mr. Timothy Reed View
11-0286 R+L Carriers, Inc. Mr. Gerald A. Krisa View
11-0285 Philips Respironics Mr. Joseph E. Olsavsky View
11-0224 Chemical Products Corporation Mr. Jerry Cook View
11-0231 View
11-0153 View
11-0197 Air Products & Chemicals, Inc. Mr. Joe DiGirolamo View
11-0204 Law Offices of James Kean Mr. James Campbell Kean View
CHI-11-003 NASA Joe Torsani View
11-0251 Allmetal Inc. Mr. Gene Guichu View
11-0268 Wiley Rein LLP Mr. George Kerchner View
11-0230 DHL Global Forwarding Ms. Dorothea A. Welk View
11-0265 A2Z Test Lab a division of MAI Mr. Arvin Blank View
11-0258 The University of North Carolina at Chapel Hill Department of Environment, Health & Safety Mr. Daniel Vick View
11-0250 W.M. Barr & Company Mr. John Rhodes View
11-0203 Henry, Oddo, Austin & Fletcher Attorneys and Counselors at Law Ms. Katherine Knight View
11-0263 c/o Waste Control Specialists LLC Mr. Jeff Shouse View
11-0211 Western Manufacturing Corp. Mr. John H. Evanski View
11-0245 DENTSPLY International, Caulk Division Mr. Kevin Marrow View
11-0196 Integrated Support Services Mr. Chuck Kimball View