Selective Testing of Packages
Pipeline and Hazardous Materials Safety Administration · Oct 26, 1992 · Reference No. 92-0141
Interprets: 49 CFR § 178.601
Reggie’s quick take
Someone asked about selective testing under § 178.601(g). The agency said Variations 1 and 4 can be combined to use smaller inner containers and a smaller outer container, as long as gross weight does not exceed the original tested design. The certification mark can show the new lower gross mass.
Written by AI (Claude) on Oct 22, 2026. Robots make mistakes and leave things out, so the letter below is what counts. Not legal advice.
This is in response to your letter regarding the selective testing of packages. I apologize for the delay in responding and hope it has not caused any inconvenience.
As provided in § 178.601(g), Variations 1 and 4 may be applied together to allow both the substitution of smaller inner containers of similar design and a proportional reduction in the external dimensions of the outer container. The new package cannot exceed the gross weight (combined weight of package and contents) of the originally tested package design type.
However, it is our opinion that the certification mark may be revised to indicate a new lower gross mass based on the calculations such as those you describe. The same third party mark would be applied to the new packaging because no design requalification is involved. RSPA does not require a person applying a selective testing variation to make note of it in the documentation of a tested design type. For completeness of the documentation, we recommend that notes be made of any design changes made under selective testing requirements.
Regarding application of Variation 2 in § 178.601(g), the specific gravity of the material to be shipped in the "V" packaging is a factor insofar as the substitute packaging cannot exceed half the gross-mass of the inner packagings and contents of the original design type tested at the packing Group I drop level. However, within that restriction, a material with a higher specific gravity in smaller inner packagings would be allowed under this variation. It is our opinion that a person cannot increase the allowable gross mass of the inner packagings in the "V" packaging by increasing the drop height above what is specified for Packing Group I.
You are correct in stating that Variation 2 allows a person to substitute "any" inner packaging, regardless of inner packaging design type changes, so long as the combined gross mass of the originally tested inner packagings, and all other provisions of § 178.601(g)(2) are complied with. Absorbent material is considered part of the completed package in determining the gross weight package marking. Also, the "V" marking is required.
If we can be of further assistance, please contact us.
A letter of interpretation applies the regulations to the facts the requester described. It isn’t a regulation and isn’t legal advice. The agency’s copy.