The edge crush test (ECT) is a measurement of the edgewise compressive strength of corrugated board. ECT tests how much weight can be stacked on top of a box without the edges being damaged. Common ECT ratings are 32 for single-wall boxes, 44-48 for double-wall boxes and 60-90 for triple wall boxes.
ECT helps determine the board’s stacking strength. It provides a reliable measurement of how well the box will hold it’s form under the vertical weight during transit.
ECT is measured by compressing a small segment of board on edge between two rigid platens perpendicular to the direction of the flutes, until a peak load is established. This is measured in pounds per lineal inch of load bearing edge (lb/in), but is usually reported as an ECT value (for example, 44 ECT).
Understanding the results of an ECT is relatively easy. If a corrugated container has a 200 ECT rating, it means that it can withstand 200 lbs of pressure on the edges of the corrugated.