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Interpretation Response #05-0204

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

Interpretation Response Details

Response Publish Date: 08-24-2006
Company Name: gh Package & Product Testing    Individual Name: Mr. H. Perry Hock
Location state: OH    Country: US

View the Interpretation Document

Response text:

Aug 24, 2006


Mr. H. Perry Hock                        Reference No. 05-0204
President and Technical Director
gh Package & Product Testing
Consulting, Inc.
4090 Thunderbird Lane
Fairfield, OH 45014

Dear Mr. Hock:

This responds to your letter requesting clarification of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) pertaining to the stack test prescribed in
§ 178.606. Specifically, you asked when is it permissible to use a “guided load” stack test, and how a guided load stack test should be set up and performed. You enclosed illustrations and photographs of the tests.

You provided a scenario as follows:

When the gh Testing laboratory performs an “unguided” stack test, using steel plates as dead load on each individual packaging or container, the packaging may fail. Frequently, the failure results in one side of the specimen collapsing and not being able to keep the weight centered above it; however, the packaging remains intact without rupture or loss of contents. Several of your clients assert that this is not a failure since the packaging is still intact and no loss of contents has occurred. You asked the following questions:

Q1.      Is my client correct that this is not a failure of the stack test since the packaging is still intact and no loss of contents has occurred?

Al.        All packaging design types other than bags must be subjected to a stacking test. The test sample must be subjected to a force applied to the top surface of the test sample equivalent to the total weight of identical packages which might be stacked on it during transport.

In a guided load stack test, a load is directed vertically onto the test sample and then maintained for a specific amount of time. Actual weights do not have to be applied. The apparatus shown in your illustrations may be used to conduct the stacking test prescribed in § 178.606, provided a constant load is applied for the 24-hour duration of the test. If this equipment is used, a stack stability assessment must be made for one hour at the conclusion of the test.

The stacking test is conducted to ensure that the inner receptacles or inner packagings do not leak any of the contents. The stability test ensures that the stacked packages are stable during transportation. There must be no leakage of the filling substance from the inner receptacle or inner packaging. No test sample may show any deterioration which could adversely affect transportation safety or any distortion likely to reduce its strength, cause instability in stacks of packages, or cause damage to inner packagings likely to reduce safety in transportation. Thus, the scenario you describe constitutes a failure of the packaging to pass the prescribed test.

Q2.      When a gh Testing laboratory places three of the same unmodified “packs” into the guided load stack test fixtures, and they pass the test, as well as the stability test that follows, are the packs considered to have passed the test?

A2.      The answer is yes.

Q3       Are the two tests supposed to give the same results?

A3.      It’s our expectation that the two stack tests (guided or unguided load) give the same or similar results.

I hope this satisfies your inquiry. If we can be of further assistance, please contact us.



John A. Gale
Chief, Standards Development
Office of Hazardous Materials Standards


Regulation Sections

Section Subject
§ 178.606 Stacking test