Abstract: Control of a pumping station is accomplished in such a manner so as to maximize the energy efficiency of the pumping station by utilizing a variable drive pump to maintain the pipeline suction pressure seen at the input to the pumping station at an acceptable level. If the pipeline suction pressure decreases below a level which can be controlled by the variable drive pump, then a control valve located at the output of the pumping station is closed to the extent necessary to maintain the pipeline suction pressure at an acceptable level. If the pipeline suction pressure is greater than can be controlled by the variable drive pump then additional pumps are brought online to prevent overloading of the variable drive pump.

Abstract: A method and apparatus is provided for interlocking the controls on flow control valve process lines entering or leaving a pipeline pig launcher or receiver to prevent opening of the launcher-receiver closure when there is pressure in the launcher-receiver vessel and to prevent inadvertent admission of flow into the vessel while the closure is not in place.