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

Interpretation Response #18-0006

Below is the interpretation response detail and a list of regulations sections applicable to this response.

Interpretation Response Details

Response Publish Date:

Company Name: Crown Packaging Technology, Inc.

Individual Name: Jaime Suarez

Location State: IL Country: US

View the Interpretation Document

Response text:

June 29, 2018

Mr. Jaime Suarez
Advisory Engineer
Crown Technology
Crown Packaging Technology, Inc.
11535 South Central Avenue
Alsip, IL 60803-3418

Reference No. 18-0006

Dear Mr. Suarez:

This letter is in response to your January 5, 2018, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the buckle ranges for a Department of Transportation (DOT) DOT 2P1. Specifically, you ask for confirmation of the buckle/burst pressure requirements of the DOT 2P1 aerosol container.

The Pipeline and Hazardous Materials Safety Administration (PHMSA) issued a final rule on January 21, 2016 under Docket No. PHMSA-2013-0042 (HM-233F) requiring all standards for a DOT 2P1 to remain the same as those for a DOT 2P, except the DOT 2P1 must also comply with the variations prescribed in § 173.33c-2. For a DOT 2P1 to comply with § 178.33c‑2, Variation 1, one container out of each lot of 25,000 containers or less, successively produced per day, complete with ends assembled (and without a pressure relief system assembled) must be pressure tested to destruction at gauge pressure and must not burst below 240 psig. The lot must be rejected if containers with a pressure relief system described in § 178.33c-2(a) and assembled show failure at a location other than the pressure relief system. For those containers with an end expansion device, the lot must also be rejected if the container bursts prior to buckling of the device.

You note how the buckle ranges for DOT 2P1 in § 178.33c‑2 differ from those prescribed in DOT Special Permit (SP) 7951. DOT-SP 7951 specifies that one out of each case lot of 10,000 cylinders or less that comply with this special permit must be pressure tested to destruction. The entire lot must be rejected if failure occurs at pressure below 175 psig and over 210 psig, or failure occurs at other than the rim-venting release device or dome expansion device.

PHMSA chose to adopt the modified DOT 2P container design prescribed in DOT-SP 13601, which complies with the DOT 2P container and variations prescribed in § 178.33c-2, as the new DOT 2P1 design. In the HM-233F final rule, PHMSA states the reasons for this are:

  • PHMSA found DOT-SPs 7951, 13601, and 14503, which authorized modified manufacturing and testing requirements for packagings similar to DOT 2P, lacked specific information on the relationship between each aerosol's functional range and tested burst pressure.
  • PHMSA found DOT-SPs 7951 and 14503 established a standard for content pressure for which there was no HMR equivalent.
  • The relief system functioning ranges in these packagings have a higher upper bound and no minimum burst pressure other than those prescribed for a DOT 2P.

I hope this information is helpful. Please contact us if we can be of further assistance.


T. Glenn Foster
Chief, Regulatory Review and Reinvention Branch
Standards and Rulemaking Division

Regulation Sections

Section Subject
173.33 Hazardous materials in cargo tank motor vehicles
178.33 Specification 2P; inner nonrefillable metal receptacles