1、Balance all of your rotating equipment. If you do not have dynamic balancing equipment in your plant there are contractors and vendors anxious to work with you. Balance is always a problem when you are pumping abrasives, or a slurry, because the rapid wear always destroys balance. In the higher speed Centrifugal Pumps this wear can be very severe.
2、Bent shafts are a problem. If you can straighten them go ahead and do it, but most attempts are unsuccessful. In the majority of cases you are better off replacing the shaft.
3、Do a proper Centrifugal Pump/ driver alignment using either a Laser or the reverse indicator method. Upgrading the Centrifugal Pump power end to a “C” or “D” frame motor adapter is a more sensible and economical decision. Once the conversion is made misalignment ceases to be a concern. These adapters are available for most motors and will maintain the proper alignment as the equipment goes through its normal temperature transients.
4、Always pipe from the Centrifugal Pump suction to the pipe rack, never the other way. There are some more piping practices that you should follow:
o If you are experiencing pipe strain because of thermal growth at the suction, you might convert to a “centerline” design wet end and solve the problem. Center line designs make sense any time you are pumping a fluid in excess of 200 degrees Fahrenheit (100 Centigrade)
o Try to use at least ten diameters of pipe between the Centrifugal Pump suction and the first elbow.
o Valve stems, T branches and elbows should be perpendicular to the Centrifugal Pump shaft not at a right angle to it. This is especially important with double suction Centrifugal Pumps because uneven inlet flow will cause the impeller to thrust in one direction causing bearing problems on one end of the Centrifugal Pump.
o Pipe supports and hangers should be installed at unequal distances.
o Use lots of hangers to support the piping.
o Use lots of loops and expansion joints in the piping system.
o After fabrication and testing remove all supports and lock pins from the spring hangers, loosen pipe flanges and adjust the system to free the Centrifugal Pump from pipe strain.
o Reference the “Hydraulic Institute Manual”, or a similar publication to learn the proper methods of piping several pumps from the same suction source to prevent vortexing etc.
5、The mass of the Centrifugal Pump concrete foundation should be five times the mass of the Centrifugal Pump, base plate and other equipment being supported.
6、The foundation should be three inches ( 75 mm) wider than the base plate, all around, up to 500 horsepower (375 KW) and six inches (150 mm) above 500 horse power (375 KW).
7、Imaginary lines, extended downward 30 degrees to either side of a vertical through the Centrifugal Pump shaft, should pass through the bottom of the foundation and not the sides.
8、Every inch of stainless steel grows 0.001 inch for every 100° Fahrenheit rise in temperature (0,001 mm/mm/50° Centigrade) This thermal growth can cause the impeller to rub the Centrifugal Pump casing as well as cause rubbing in many close tolerance clearances such as the wear rings. Carbon steel grows about 30% less than stainless steel.
9、Any time the shaft moves there is the danger of parts rubbing. Thermal imaging equipment can detect this rubbing easily. When ever you set tight tolerances be sure to allow for thermal growth and, in the case of A.N.S.I. Centrifugal Pumps, impeller adjustment.
10、Worn or loose bearings are caused by improper installation or allowing water to enter the bearing cavity. Labyrinth seals or positive face seals are the easiest solution to the water problem. Install bearings by using a proper induction heater to prevent contamination during the installation process.
11、The answer to loose hold down bolts is obvious and requires no explanation.