Primary Air (P.A.) fans force air into the furnaces of coal-fired power plants. Rotating at 1,600 RPM, they have to be solid, balanced and reliable.
Here is a new P.A. fan. It has been welded and the center hub riveted. The welds are then inspected to AWS D14.6 Standards using Magnetic Particle Inspection.
The fans are then balanced; much like you’d balance the wheels on your car. The shafts are also balanced and a mated set is created to ensure smooth rotation and a long service life.