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Section §172.304: Marking requirements

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 172.304 on the ECFR website

Interpretation Responses

Ref ID Date Company Name Individual Name Response Document
16-0198 C&J Energy Services Ltd. Mr. George Doggett View
02-0166 AFGO Laboratories, Inc. Dale D. Benincasa View
13-0169 SC Johnson & Son, Inc Ms. Georgia Barr View
11-0098 The Sherwin-Williams Company Ms. Sandra Chapman Th View
15-0078 Maryland Department of Environment Mr. Michael Polinski View
14-0221 WTS, Inc. Mr. Brian Burns View
12-0146 ADG Compliance Manager Mr. Bob Cogen View
16-0055 AZKO Nobel Services, Inc. Mr. Mark Connolly View
09-0174 Mr. Steven H. Wodka View
10-0247 View
07-0157 FedEx Express Mr. Thomas J. Leech, III View
14-0195 The Clorox Company Mr. Maurice C. Carson View
11-0078 Mr. Roger W. Cooper View
01-0316 UPS Corporate Hazardous Ms. Mary Beth View