Modification of Mobile Intermediate Bulk Containers

It is permitted to register a modified design of an IBC without retesting as specified in clause 8.1 or with limited re-testing as specified in clause 8.2 of the CAN/CGSB-43.146 standard. The tested design type becomes the “mother design” that allows construction of certain “daughter designs” without re-testing or with reduced re-testing.

Among the criteria for reduced testing in the standard is that overall dimensions may be “reduced in the same proportion” and that the “height …may be reduced”. The standard does not provide direction regarding what constitutes an acceptable tolerance on the “same proportion” so we provide the following guidance. Since we consider 2% to be an acceptable tolerance on length measurement for design registration, we will generally accept 5% as an acceptable variation on the ratio of two “overall dimensions”.  We consider the dimensions of a “daughter design” IBC to have been reduced in the same proportion if the length/width ratio of the “daughter design” differs by 5% or less of the length/width ratio of the “mother design” and the ratio of each dimension of the “daughter design” over the same dimension on the “mother design” differs by 5% or less. The length and diameter of a cylindrical tank may be similarly be reduced without retesting.

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