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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
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
11-0201 Arkema, Inc. Ms. Christina Kurtz View
11-0182 Mr. Henry Wake Huffman View
11-0183 Rit-Chem Co., Inc. Mr. Henry L. Ritell View
11-0195 Gh Package/Product Testing and Consulting, Inc Mr. Perry Hock View
11-0181 McAda Fluids Heating Services Mr. James S. McAda View
10-0217 Mr. Daniel J. VenRoy View
11-0238 NitroxFox LLC. Mr. John Fox View
11-0242 Dynax Corporation Chang Jho, Ph.D. Dynax Corporation View
11-0190 Action Resources Mr. Douglas R. Carothers View
11-0011 Sunny Point Military Ocean Terminal - DSN 488 Ms. Lonnie Burks View
11-0210 Patterson Companies, Inc. Mr. Robb Boros View
11-0216 Mirion Technologies Mr. James E. Lynch View
11-0239 Huntsman Corporation Raymond Papciak and Mike Stillwell View
10-0115 Jacobus Energy Mr. John Klein View
11-0220 Foster Fuels, Inc. Mr. John George View
11-0186 Mr. Tae Kim View
11-0140 Law Office of Seaton & Husk, L.P. Mr. Henry E. Seaton Esq. View
11-0244 Arch Chemicals, Inc. Ms. Jennifer M. Daugherty View
10-0245 Air Transport International, L.L.C. Mr. Dave Bell View
10-0189 Oak Point Service Mr. Jim Poulsen View
11-0128 Oregon Department of Environmental Quality Mr. Brian Allen View
11-0223 Lockheed Martin - Sippican Mr. Matthew Sears View
11-0168 United Brands Mr. Jimmy Zahriya View
11-0167 Kiewit Infrastructure South Company Ms. Holly Stringer View