§ Appendix B to Part 172 Appendix B to Part 172—Trefoil Symbol

PART 172—HAZARDOUS MATERIALS TABLE, SPECIAL PROVISIONS, HAZARDOUS MATERIALS COMMUNICATIONS, EMERGENCY RESPONSE INFORMATION, TRAINING REQUIREMENTS, AND SECURITY PLANS, last amended 2016-08-15

Official text from eCFR.gov, up to date as of 2026-10-22. Checked for changes every day.

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1. Except as provided in paragraph 2 of this appendix, the trefoil symbol required for RADIOACTIVE labels and placards and required to be marked on certain packages of Class 7 materials must conform to the design and size requirements of this appendix.

2. RADIOACTIVE labels and placards that were printed prior to April 1, 1996, in conformance with the requirements of this subchapter in effect on March 30, 1996, may continue to be used.

1 = Radius of Circle—

Minimum dimensions

4 mm (0.16 inch) for markings and labels

12.5 mm (0.5 inch) for placards

2 = 1 1/2 Radii

3 = 5 radii for markings and labels

4 1/2 radii for placards.

Official text from the eCFR. The eCFR is an authoritative but unofficial editorial compilation; the Federal Register is the legal source.