Within the petroleum industry centrifugal pumps are necessary in order to process fluids especially hydrocarbons. Another important application within the petroleum industry is in the mud circuit on a drilling rig. On drilling rigs, mud which consists mainly of water and bentonite as well as of several different additives depending on many different factors is used. The heart of the mud circuit is the mud pump which is in general a high pressure piston pump. It provides the major part of head to overcome the system’s resistance. The mud is pumped through a piping system to the derrick and through the standpipe to a definite high. Now through the kelly hose via the gooseneck into the upper kelly cock. It flows through the Kelly and the lower kelly cock into the drill string down the borehole. At its end, the mud leaves the drilling collars through the drilling bit.
Standard centrifugal pumps are not self-priming and require the fluid end to be primed prior to activation. This can be accomplished by installing the pump in a location that provides a flooded suction or by using a device to prime the pump. Once the pump casing is full of fluid, it can then be energized. Running a pump dry or restricting suction flow can severely damage the fluid end, mechanical seal, or packing. The designs of self-priming pumps result in turbulent flow patterns, which cause excessive wear during pumping of abrasive fluids and increase operating costs. The drilling industry avoids using self-priming pumps due to increased downtime and costs.
Many factors affect performance of a centrifugal pump and must be considered during pump selection. This chapter describes conditions that affect the centrifugal pump and is followed by details that will assist in eliminating negative conditions that cause pump failure.