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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 #13-0178 ([ThyssenKrupp North America, Inc.] [Mr. Michael J. Bauer])

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

Interpretation Response Details

Response Publish Date:

Company Name: ThyssenKrupp North America, Inc.

Individual Name: Mr. Michael J. Bauer

Location State: IL Country: US

View the Interpretation Document

Response text:

January 27, 2014

Mr. Michael J. Bauer
ThyssenKrupp North America, Inc.
111 W. Jackson Blvd.
Suite 2400
Chicago, IL 60604

Ref No.: 13-0178

Dear Mr. Bauer:

This is in response to your May 22, 2013 letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) with regard to the testing of accumulators.  Specifically, you seek confirmation that the methods you use for design-type testing are in conformance with the HMR.  In your letter, you provide details on the testing procedures you use for testing of accumulators prior to shipment and indicate that the products are classified as “UN3164, Articles, pressurized, pneumatic (containing nitrogen), Division 2.2.”  

In your letter you state that your accumulators otherwise meet the requirements in §§ 173.306(f)(2), (f)(3) or (f)(4), as applicable for the design type.  Accumulators shipped under the requirements of these sections are subject to pressure testing requirements.  To conduct the burst pressure testing you utilize a hydrostatic pressure test of at least three accumulators of each design type and charge each accumulator to the pressures indicated in in §§ 173.306(f)(2)(iii), 173.306(f)(3)(ii) and 173.306(f)(4)(ii).  While these sections require testing prior to shipment and before each refilling and reshipment, the HMR do not specify what type of pressure test is required.  However, the method you describe satisfies the requirements of §§ 173.306(f)(2)(iii), 173.306(f)(3)(ii) and 173.306(f)(4)(ii) for the pressure testing of accumulators, classified as “UN3164, Articles, pressurized, pneumatic (containing nitrogen), Division 2.2.”  It should be noted that while the method you describe satisfies the minimum burst pressure requirements for the design, each accumulator must be tested to at least three times the charge pressure at 70 °F before initial shipment and before each refill and reshipment per §§ 173.306(f)(2)(iii) and 173.306(f)(3)(i).  The results of this test for each accumulator must show no evidence of failure or damage.

Additionally, for the fire test required by § 173.306(f)(4) for accumulators intended to function as shock absorbers, struts, gas springs, pneumatic springs or other impact or energy-absorbing devices you indicate that you subject each design-type to the fire test specified in the Compressed Gas Association (CGA) pamphlet C-14.  While CGA C-14 is not incorporated by reference in this section, provided the fire test demonstrates that the article relieves its pressure by means of a fire degradable seal or other pressure relief device, such that the article will not fragment and that the article does not rocket, in accordance with § 173.306(f)(4)(iii) it would satisfy the requirements of the HMR, provided it meets the other requirements of this provision.

I hope this information is helpful.  We apologize for the delay in our response and any inconvenience it may have caused.  If you have any more questions, please do not hesitate to contact this office.


Robert Benedict
Chief, Standards Development
Standards and Rulemaking Division


Regulation Sections

Section Subject
173.306 Limited quantities of compressed gases