High-pressure feed water pump (reciprocating pump) inlet and outlet cross-pipes for hydrocracking

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I have seen that on the inlet and outlet of the injection pumps (reciprocating pumps) in many devices, there is a cross-connected line. What is the specific function of this cross-connected line? Is it only meant to be used as a pump for trial operation in standalone mode, or is it also used to balance the inlet and outlet pressures in tank pumps? I’ve seen some systems use this cross-line to adjust the outlet flow rate when starting the pump, that is, to serve as a minimum flow line. But I don’t think that’s correct, because it doesn’t function as a minimum flow line – it doesn’t return from the outlet to the tank but rather directly back to the inlet pipeline. If this is used to adjust the outlet flow rate after the pump is started, the high pressure at the outlet will flow back to the inlet via this shortcut, which will inevitably cause overpressure at the inlet. So I’d like to discuss with everyone what the purpose of designing this cross-line is I feel that it doesn’t play a significant role when the pump is running, and I think it should absolutely not be used to control the outlet flow while the pump is in operation. Please share your own opinions as well.