Avoiding cavitation in a pump is a concern in all services but particularly when the liquid operates close to the vapor pressure.
Boiler feed pumps, shown below, generally operate close to the vapor pressure of the feed water. As a result, it is imperative that changes in direction be minimized. Designers may add flexibility to the suction line when it is convenient to support it, but this may disrupt the flow and increase the possibility of cavitation.
The preferred arrangement has a maximum straight drop out of the deaerator down to where the flexibility loop is required. Although support may be more difficult, optimizing the operation of the pump is of primary concern and should take precedence.