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

Interpretation Response #06-0200 ([Mr. Robert D. Howerton, Ph.D.])

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: Mr. Robert D. Howerton, Ph.D.

Location State: GA Country: US

View the Interpretation Document

Response text:

Sep 27, 2006


Mr. Robert D. Howerton, Ph.D.                 Reference No. 06-0200
2582 Wood Trail Lane
Decatur, GA 30033

Dear Dr. Howerton:

This is in response to your electronic transmission requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) as they pertain to the rebuilding of accumulators. Specifically, you ask for a procedure whereby you would notify and receive corroboration from the U.S. Department of Transportation (DOT) or a third party that the rebuilt accumulators can withstand at least 5,000 psi, and that the pressure test apparatus that you are building is capable of testing the accumulators at the required pressure. Additionally, you ask about exceptions under the HMR applicable to transporting accumulators, and whether any records are required to be maintained for the rebuilt accumulators.

Under the HMR, if your rebuilt accumulators meet the requirements in § 173.306(0(1) through (f)(4)(iv), you are not required to submit supporting documentation to the DOT. The DOT does not verify test results nor does it approve pressure test apparatus for accumulators meeting the above requirements; however, you may elect to receive substantiation from a third party. As stated in § 173.306(0(5), if the accumulators do not meet the requirements in § 173.306(0(1) through (f)(4)(iv), you must apply for an approval in accordance with Subpart H of Part 107 before the accumulators may be transported.

With respect to exceptions applicable to accumulators, you state that the accumulators meet the requirements in § 173.306(0(3). Provided the accumulators have a charging pressure exceeding 200 psig at 70° F, the articles are not required to be labeled (except for transportation by air) and are additionally excepted from specification packaging requirements provided the articles meet the requirements in § 173.306(0(2) through (0(3)(ii). These accumulators are not accepted from the HMR’s shipping paper requirements by any mode of transportation.

In response to your question asking whether any records are required to be maintained, § 173.306(0 (4) (iv) requires a written quality assurance program to be maintained at each facility at which the accumulators are manufactured. As specified in § 173.306(f) (4)(iii), the program must monitor parameters controlling burst strength, burst mode and performance in a fire situation.

Finally, we note that you referenced “Nitrogen, compressed,” UN1066 in your letter. When selecting a proper shipping name, the name that most appropriately describes the article or material being transported must be chosen. Hydraulic accumulators containing non-liquefied, non-flammable gas, and non-flammable liquids are most appropriately described as “Accumulators, pressurized, hydraulic,” UN3164. Pneumatic accumulators containing non-liquefied, non-flammable compressed gas are most appropriately described as “Accumulators, pressurized, pneumatic” UN3164.

I hope this information is helpful. Please contact this office if you need additional assistance.



Hattie L. Mitchell
Chief, Regulatory Review and Reinvention
Office of Hazardous Materials Standards


Regulation Sections

Section Subject
173.306 Limited quantities of compressed gases