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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
04-0133 National Propane Gas Association Mr. Philip A. Squair View
02-0006 Railroad Commission of Texas Gas Services Division Richard L. Gilbert View
03-0242 Morris County Municipal Utilities Authority Ms. Laura MacPherson View
03-0198 Heritage Environmental Services Mr. David E. Blair View
03-0033 Nebraska State Patrol Bradley A. Wagner, Sergeant View
03-0285 Blue Rhino Corporation Mr. Richard J. Arthur View
03-0201 Gulf Trading (Alabama), Inc. Mr. Mark Walker View
03-0328 The Fertilizer Institute Mr. Kraig R. Naasz, President View
PI-03-0107 DOT Compliance Coordinator Enterprise Products Operating L.P. Mr. Mark J. Cartwright View
03-0251 URS Corporations Mr. Andrew N. Romach View
03-0265 The Daniels Corporation Ms. Terry Grimmond View
03-0245 HMT Associates, L.L.C. Mr. E. A. Altemos View
03-0254 CONSIDAR, Inc. Ms. Noreen McDonald View
03-0159 Airgas, Inc. Mr. John Anderson View
03-0257 URS Corporation Mr. Andrew N. Romach View
03-0224 ShipMate, Inc. Mr. Steven Charles Hunt View
03-0243 Quaker Chemical Corporation Ms. Kathryn F. Strang, CHMM View
03-0262 Mr. Leighton Ford View
03-0225 Arbonite Mr. Lee K. Robinson View
03-0202 Mr. Steve Thinnes View
03-0261 Carleton Technologies, Inc. Ms. Elizabeth Campbell View
03-0226 Dinda & Associates, Inc. Mr. John F. Dinda, Jr. View
03-0102 Palava Consulting Services Mr. Richard Palava View
03-0179 Ray-Vin.Com Mr. Raymond V. Brandes View
03-0231 American Trucking Associations (ATA) Mr. Richard Moskowitz View
03-0252 Myers Industries, Inc. Ms. Barb Germano View
03-0258 URS Corporation Dear Mr. Romach: View
03-0247 Myers Industries, Inc. Ms. Barb Germano View
03-0238 Exide TecImologies Mr. David M. Bloom View
03-0332 Dangerous Goods Advisory Council Mr. Alan I. Roberts View
03-0237 The Sherman-Williams Company Ms. Sandra L. Basham View
03-0197 Olin Corporation Mr. G. W. Kovarik View
03-0329 Dangerous Goods Advisory Council Mr. Alan I. Roberts View
03-0216 Classic Propane Ms. Toni Yount View
03-0195 California Highway Patrol Officer George Barber View
03-0227 OHKA America, Inc. Mr. Felix J. Stephens View
03-0167 McCarthy, Sweeney & Harkaway, P.C. Mr. Lawrence W. Bierlein View
03-0219 Department of the Navy Mr. Daniel J. Burke View
03-0229 Lion Technology, Inc. Mr. Marc Kleinman View
03-0218 CONSIDAR, Inc. Ms. Noreen McDonald View
03-0209 Mr. Lovell Goodwin View
03-0194 Fisher Scientific LLC Mr. Gene Sanders View
PI-03-0106 Southwest Gas Corporation Mr. James F. Wunderlin, P.E. View
03-0136 CERAC Incorporated Ms. Candace Graf  View
03-0206 Chemplex L.C. Mr. Edward F. Vinson View
03-0118 Waste Technology Services, Inc. Mr. Ted Nebrich View
03-0098 RP Kelley Enterprises, Inc, Mr. Roland M. Kelley View
03-0181 R and J Trucking Mr. Daniel J. Fire View
03-0156 AGA Gas, Inc. Mr. Guy Dalton View
03-0061 MHF Logistical Solutions Mr. Kenneth M. Grumski View