Final answer:
The pump should be aligned with the discharge flange before fitting the pipe to ensure optimal operation and to prevent undue stress on the pump components.
Step-by-step explanation:
When setting up a pump system, proper alignment between the pump and the discharge flange is crucial for efficient operation and to prevent premature wear and failure of the pump components. The correct time to align a pump in relation to the discharge flange is b) Before fitting the pipe. Aligning the pump before the piping is connected ensures that the pump's shaft is aligned with the driver, reducing stress on the bearings, shaft, and seals. If the pump is aligned after the pipes have been fitted, the existing stresses or misalignment from the piping system could be transferred to the pump, leading to operational issues or the need for premature maintenance.