USA Banner

Official US Government Icon

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure Site Icon

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

49 CFR Parts 100-199

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

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 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

Search the eCFR

E.g., 02/09/2021
E.g., 02/09/2021
Part/Section Subject
173.315 Compressed gases in cargo tanks and portable tanks
173.316 Cryogenic liquids in cylinders
173.319 Cryogenic liquids in tank cars
173.32 Requirements for the use of portable tanks
173.320 Cryogenic liquids; exceptions
173.322 Ethyl chloride
173.33 Hazardous materials in cargo tank motor vehicles
173.334 Organic phosphates mixed with compressed gas
173.336 Nitrogen dioxide, liquefied, or dinitrogen tetroxide, liquefied
173.35 Hazardous materials in IBCs
173.36 Hazardous materials in Large Packagings
173.4 Small quantities for highway and rail
173.40 General packaging requirements for toxic materials packaged in cylinders
173.401 Scope
173.403 Definitions
173.41 Sampling and testing program for unrefined petroleum-based products
173.410 General design requirements
173.411 Industrial packages
173.412 Additional design requirements for Type A packages
173.415 Authorized Type A packages
173.416 Authorized Type B packages
173.417 Authorized fissile materials packages
173.418 Authorized packages-pyrophoric Class 7 (radioactive) materials
173.419 Authorized packages-oxidizing Class 7 (radioactive) materials
173.421 Excepted packages for limited quantities of Class 7 (radioactive) materials
173.422 Additional requirements for excepted packages containing Class 7 (radioactive) materials
173.423 Requirements for multiple hazard limited quantity Class 7 (radioactive) materials
173.424 Excepted packages for radioactive instruments and articles
173.425 Table of activity limits-excepted quantities and articles
173.426 Excepted packages for articles containing natural uranium or thorium
173.427 Transport requirements for low specific activity (LSA) Class 7 (radioactive) material and surface contaminated objects (SCO)
173.428 Empty Class 7 (radioactive) materials packaging
173.433 Requirements for determining basic radionuclide values, and for the listing of radionuclides on shipping papers and labels
173.435 Table of A1 and A2 values for radionuclides
173.436 Exempt material activity concentrations and exempt consignment activity limits for radionuclides
173.441 Radiation level limitations and exclusive use provisions
173.443 Contamination control
173.447 Storage incident to transportation-general requirements
173.448 General transportation requirements
173.453 Fissile materials-exceptions
173.457 Transportation of fissile material packages-specific requirements
173.459 Mixing of fissile material packages with non-fissile or fissile-excepted material packages
173.461 Demonstration of compliance with tests
173.465 Type A packaging tests
173.467 Tests for demonstrating the ability of Type B and fissile materials packagings to withstand accident conditions in transportation
173.469 Tests for special form Class 7 (radioactive) materials
173.475 Quality control requirements prior to each shipment of Class 7 (radioactive) materials
173.476 Approval of special form Class 7 (radioactive) materials
173.4a Excepted quantities
173.4b De minimis exceptions