Why does FPCo object to the use of column pipe centralizers?
The design intent of a vertical turbine pump is that the impellers hang (like a plumb bob on a string) on the lineshaft. It should, when at rest and at full speed, never touch the fluted rubber bearings. The purpose the lineshaft bearings serve is to stabilize the shaft during startup. As an example; if you spin the plumb bob on the string you will note the string will knot-up. The same thing happens to the lineshaft when starting torque is applied, the shaft distorts. The bearings are there to minimize the distortion. The shaft straightens out when it reaches operating speed (Un-winds) and thrust load is applied. With that in mind, no side load should be exerted on the column pipe that might cause the bearings to bind or attempt to bend the lineshaft. If the lineshaft is so affected the pump will vibrate, or wear out the bearings causing the lineshaft to fail, or break the quill (hollow) shaft in the driver or cause the bearings in the driver to fail. When you consider that the FPCo s
