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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 #20-0066

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

Interpretation Response Details

Response Publish Date:

Company Name:

Individual Name: Paul Horgan

Location State: CA Country: US

View the Interpretation Document

Response text:

November 23, 2020

Paul Horgan
353 Porter St.
Woodland, CA  95695

Reference No. 20-0066

Dear Mr. Horgan:

This letter is in response to your August 20, 2020, email requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) applicable to the requirements in § 180.407 pertaining to testing and inspection of specification cargo tanks. Specifically, you ask whether inspection of a cargo tank using the wet fluorescent magnetic particle method is required for MC330 and 331 cargo tanks in dedicated carbon dioxide refrigerated liquid service. In addition, you ask whether carbon dioxide refrigerated liquid is considered a source of stress corrosion cracking in SA 517E type steel, quenched and tempered cargo tanks.

The need to use the wet fluorescent magnetic particle method must be determined by the cargo tank motor vehicle (CTMV) owner and the Registered Inspector (RI) performing the inspection of the CTMV based on knowledge and experience of MC 330 or 331 in this service. As provided in § 180.407(g)(3), the wet fluorescent magnetic particle method must be performed to internally inspect a cargo tank used to transport any hazardous material that may cause stress corrosion cracking prior to and in conjunction with the performance of the pressure test requirements. Furthermore, the CTMV owner and the RI may use publicly available information or rely on their operations and maintenance records to aid in determining whether a hazardous material may cause stress corrosion cracking and the necessary method for inspection.

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


Dirk Der Kinderen
Chief, Standards Development Branch
Standards and Rulemaking Division

180.407, 180.407(g)(3)

Regulation Sections

Section Subject
180.407 Requirements for test and inspection of specification cargo tanks