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Section §173.120: Class 3-Definitions

Below are the available interpretations and guidance for the given section. To return to the list of parts, use the Parts link above. If you do not see any guidance or interpretation information below, that means there is none available for the given part/section. Return to the search page to browse additional regulations sections.

PHMSA has published several Frequently Asked Questions (FAQ) documents on regulatory topics. Please review our FAQ documents below:

Additionally PHMSA has Hazardous Materials FAQs based on letters of interpretation on the following topics:

This section of the website provides the ability to find regulations information including regulations parts, content of sections, and interpretations for regulations sections. Below is a list of parts, identified by the part number and subject. 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.

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: 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.

The regulations text of the section can be found on the eCFR website. To view the regulations text, use the link below. For assistance, please send an email to

View section 173.120 on the ECFR website

Interpretation Responses

Ref ID Date Company Name Individual Name Response Document
22-0107 Roadrunner Transportation System LLC Mr. Karl Kronau View
22-0020 Justin Lacy View
21-0115 Intermodal Tank Transport Jasmine Builes View
21-0065 Smarter Sorting AJ Kenny View
20-0061 LG Chem Michigan, Inc. Ms. Sarah Kim View
20-0044 Railsback Safety Professionals LLC Rex Railsback View
20-0034 Railsback Safety Professionals LLC Rex Railsback View
18-0110 Ascent Resources Utica, LLC Steven Parrish View
18-0043 Ventura County District Attorney's Office Mitchel Disney View
17-0066 Tyco Fire Protection Products Ms Kym Seth View
12-0108 Wercs Professional Services Mr. Kevin Skerrett View
05-0272 Patterson Dental Supply, Inc. Mr. Robb Boros View
08-0066 Montana Motor Carrier Services Enforcement Division Lt. Jeff McLaughlin View
13-0212 Anpersan, LLC Mr. Gary P. Sanders View
99-0251 Thompson, Hine & Flory L.L.P. Norman J. Philion, Esq. View
98-0519 The Defense Contract Management Command Ms. Jill E. Pettibone View
11-0205 AT&T Mr. Jim La Porte View
14-0027 URS Corporation Mr. Andrew Romach View
02-0121 Thomas J. Leech, III View
05-0172 McCarthy, Sweeney & Harkaway, P.C Mr. Lawrence W. Bierlein View
08-0209 Biodiversity Research Institute University of Kansas Mr. Andrew Bentley View
14-0058 Transportation Systems Solutions Mr. Peter Olsen View
08-0182 ACCO Brands Corporation Mr. Darren Lenox View
09-0093 Valspar Mr. Eric Barcaskey View
15-0130 Green Environmental Consulting Ms. Peggy Haase View
07-0017 The Valspar Corporation Eric Barcaskey View
06-0134 Special Materials Company Mr. Adam Feldman View
06-0121 Hydrol Chemical Co., Inc. Mr. Richard W. Hoffman, Jr.  View
03-0010 TNT Logistics North America Mr. Michael J. Marino View
12-0230 Boreal Aviation, Inc. Mr. Bob Henning View
11-0242 Dynax Corporation Chang Jho, Ph.D. Dynax Corporation View
08-0103 Anodamine, Inc. Mr. Paul R. Hattingh View
10-0172 Forth Infrastructure & Environment, LLC Ms. Michele L. Frozena View
08-0010 D.B. Western, Inc. - Texas Mr. Phil Johnson View
PI-98-0101 U.S. Department of Transportation Richard Sanders View
07-0111 Dr. Lilly Langer View
01-0239 T. Hasegawa USA Inc. Mr. Sean F. Surbeck View
01-0289 Enefco International, LTD. Mr. James F. Timmins View
15-0051 Scientific Innovations, LLC Mr. Steve Foster View
10-0059 Bureau of Waste Prevention Massachusetts Department of Environmental Protection Mr. Bill Sirull Chief View
08-0284 Momentive Performance Materials Mr. Michael T. Shamulka  View
07-0076 Natural History Museum of Los Angeles County Mr. Leonard M. Navarro View
11-0141 Kajuligan Corporation Mr. Clifford Croft View
07-0076R Natural History Museum Of Los Angeles County Mr. Leonard M. Navarro   View
13-0054 TOM DOLCE Training Associates Mr. Thomas Dolce View
05-0191 Industrial Health and Safety Consultants, Inc. Denese A. Deeds, CIH View