Rectangular Expansion Joints

Small Radius Round Corner Expansion Joints

The most common, simple metal expansion joint for rectangular ductwork typically has hand welded mitered corners. While easy to fabricate, this particular corner configuration has high stresses in the corner during operation and is prone to cracking after a low number of cycles.

Since fatigue failures in rectangular expansion joints generally occur at the corners, a vast improvement in corner fatigue cycle life can be achieved by the use of a round corner confi guration.

Until recently, round corners for these type of joints had a large inside radius, (- 12”) and a short convolution height (-2 1/2”) due to manufacturing limitations. These large radii complicated the fabrication of the frame and created signifi cant flow obstructions within the duct while the short convolution height limited the movement capability.

However, new Senior Flexonics Pathway manufacturing capabilities allow for much smaller inside radii 11/2” with convolution heights of 3”, 51/2” and 8”. Comparative testing indicates that for a mitered corner cycle life of 100 cycles, the new radius corner design would provide 7500 cycles!

These improvements along with less flow obstruction and easier fabrication make this new corner style advantageous in refurbishment applications as well as new rectangular expansion joint applications.

To find out more about round corner rectangular expansion joints contact Senior Flexonics Pathway at info@myej. net.