FD Fan Blade Protection and Balance

The challenge

A forced-draft fan feeding a furnace pulls particulate-laden air across its blades hour after hour, and that particulate wears the blade tips down and roughens the faces. As the metal comes off unevenly, the rotor falls out of balance and starts to vibrate, which loads the bearings and shakes the whole assembly. The worn, roughened blades also drag against the air stream and move less of it, so the fan no longer delivers the airflow the furnace needs to run. Left to keep wearing, the imbalance and the lost airflow force the fan, and the furnace behind it, out of service.

The Belzona approach

The rotor comes down and the blades are stripped to clean metal, showing exactly where the tips and faces have worn. A Belzona composite rebuilds the worn tips and faces cold, putting the metal back where the particulate took it and bringing the blade geometry back toward its original shape. An erosion-resistant coating then goes across the blade surfaces, smooth enough to cut the drag and tough enough to take the particulate. With the geometry rebuilt evenly across the blades, the rotor comes back toward balance, and the smooth surface restores the airflow the furnace needs while giving the blades a wear face that holds up.

1. Assess and stripThe rotor is pulled and the blades stripped to clean metal to see where the tips and faces have worn and how far the rotor has gone out of balance.
2. Surface preparationThe blade surfaces are blasted to a clean, profiled metal so the rebuild composite and the coating bond properly.
3. Rebuild tips and facesA Belzona composite rebuilds the worn tips and faces cold, worked with no heat so the blades see no distortion.
4. Coat the wear facesAn erosion-resistant coating goes across the blade surfaces, smooth to cut drag and tough enough to take the particulate in the air stream.
5. Balance and return to serviceThe rebuilt geometry is confirmed to bring the rotor back toward balance, and the fan is handed back ready to feed the furnace.