(a)General. The stacking test must be conducted for the qualification of all Large Packagings design types intended to be stacked.
(b)Special preparation for the stacking test.
(1) All Large Packagings except flexible Large Packaging design types must be loaded to their maximum permissible gross mass.
(2) Flexible Large Packagings must be filled to not less than 95 percent of their capacity and to their maximum net mass, with the load being evenly distributed.
(1) All Large Packagings must be placed on their base on level, hard ground and subjected to a uniformly distributed superimposed test load for a period of at least five minutes (see paragraph (c)(5) of this section).
(2) Fiberboard and wooden Large Packagings must be subjected to the test for 24 hours.
(3) Rigid plastic Large Packagings which bear the stacking load must be subjected to the test for 28 days at 40 °C (104 °F).
(4) For all Large Packagings, the load must be applied by one of the following methods:
(i) One or more Large Packagings of the same type loaded to their maximum permissible gross mass and stacked on the test Large Packaging;
(ii) The calculated superimposed test load weight loaded on either a flat plate or a reproduction of the base of the Large Packaging, which is stacked on the test Large Packaging; or
(5)Calculation of superimposed test load. For all Large Packagings, the load to be placed on the Large Packaging must be 1.8 times the combined maximum permissible gross mass of the number of similar Large Packaging that may be stacked on top of the Large Packaging during transportation.
(1) The package must be tested in accordance with § 178.980(c) of this subpart; or
(2) The packaging may be tested using a dynamic compression testing machine. The test must be conducted at room temperature on an empty, unsealed packaging. The test sample must be centered on the bottom platen of the testing machine. The top platen must be lowered until it comes in contact with the test sample. Compression must be applied end to end. The speed of the compression tester must be one-half inch plus or minus one-fourth inch per minute. An initial preload of 50 pounds must be applied to ensure a definite contact between the test sample and the platens. The distance between the platens at this time must be recorded as zero deformation. The force “A” to then be applied must be calculated using the applicable formula:
Liquids: A = (1.8)(n−1) [w (s × v × 8.3 × .98)] × 1.5;
Solids: A = (1.8)(n−1) [w (s × v × 8.3 × .95)] × 1.5
A = applied load in pounds.
n = maximum number of Large Packagings that may be stacked during transportation.
w = maximum weight of one empty container in pounds.
s = specific gravity (liquids) or density (solids) of the lading.
v = actual capacity of container (rated capacity outage) in gallons.
8.3 corresponds to the weight in pounds of 1.0 gallon of water.
1.5 is a compensation factor that converts the static load of the stacking test into a load suitable for dynamic compression testing.
(e)Criterion for passing the test.
(1) For metal or rigid plastic Large Packagings, there may be no permanent deformation which renders the Large Packaging unsafe for transportation and no loss of contents.
(2) For flexible Large Packagings, there may be no deterioration which renders the Large Packaging unsafe for transportation and no loss of contents.
(3) For the dynamic compression test, a container passes the test if, after application of the required load, there is no permanent deformation to the Large Packaging which renders the whole Large Packaging; including the base pallet, unsafe for transportation; in no case may the maximum deflection exceed one inch.