Grammage and ECT (Edge Crush Test) in the performance assessment of fibreboard boxes

Through new techniques and advancements, fibreboard manufacturers can produce fibreboard with less material while maintaining its strength, measured through ECT. Transport Canada is interested in undertaking research to determine whether ECT value alone can be a sufficient metric in determining the performance capability of a single or double wall corrugated fibreboard box or whether the grammage (i.e. basis weight) value is a necessary component in demonstrating fibreboard box performance in accordance with UN performance testing and allowable design variations.

The safety standard applicable to fibreboard boxes for transport of dangerous goods currently in force in Canada is the TP 14850 -2010 edition, which has been in force since 2014. This Standard permits a design variation of +/- 5% in the grammage value of each layer of fibreboard without requiring further performance testing of the box design (as long as other general elements of the design and fibreboard construction remain the same, including layer combination, ECT value, flute and orientation of corrugations). However, in the proposed new edition of the small container safety standard, the +/-5% variation was removed as it could rarely, if ever, be met by stakeholders.

TP 14850 – under Chapter 8. PERMITTED DESIGN VARIATIONS: “8.1.2.7 Material substitution of code 4G fibreboard box – For code 4G fiberboard boxes, the outer packaging material may be substituted by an equivalent material having a different grammage if: a. for each corresponding layer, the difference between the grammage of the new material and the grammage of the successfully tested material is within +/- 5%; and b. the construction of the fibreboard remains the same (layer combination, ECT value, flute and orientation of corrugations).”

In order to continuously meet the requirements of the standard, stakeholders (i.e. shippers who assemble combination packaging consisting of an inner package and outer fibreboard box) are required to demonstrate that all fibreboard specifications (ECT, flute, and grammage) are consistent with the specifications on file with Transport Canada when the packaging design was registered or are within the permitted variations within the Standard. The fibreboard industry in Canada markets fibreboard boxes by its ECT value. Because of the emphasis on ECT value, it is difficult for stakeholders to obtain the grammage information, and further, as the grammage values often differ from the original information or do not fall within permitted variation, stakeholders are required to retest the entire packaging design or demonstrate how the packaging can still meet same performance.

The purpose of this study is to obtain a greater understanding of the performance of corrugated fibreboard boxes with varying grammage configurations but equivalent Edge Crush Test (ECT) values. The data resulting from the testing conducted as part of this study will be used and analysed by Transport Canada to determine if grammage variation requirements can be updated, removed, or replaced.

This project will be achieved by performing UN standardized performance testing on combination packagings, a packaging comprised of one or more inner packaging within an outer packaging. For this project, each combination packaging contains a fibreboard box (outer packaging) and four (4) HDPE rounded-off square bottles (inner packagings). Additionally, non-standarized compression tests to failure will be performed on the outer packaging without the inner packaging. Fibreboard boxes tested will have equivalent ECT values and varying grammages.