backup heat exchanger 40 to maintain backup heat exchanger 40 in a cold standby mode in a preferred embodiment the output of backup heat exchanger 40 is combined with the output product stream the method may further comprise providing that a pressure at an inlet of backup heat exchanger 40 is approximately equal to a pressure at an inlet of main heat exchanger 16 during normal operation to maintain backup heat exchanger and the liquid transfer lines thereto in a cold startup mode for immediate operation and so that gas vaporized in backup heat exchanger 40 is at the desired regulated pressure the method may further comprise changing from normal operation to backup operation by shutting off flow of the liquefied gas stream to normally operating or main heat exchanger 16 and diverting all of the remaining liquefied gas stream to backup heat exchanger 40 other steps may comprise at least temporarily continuing to pump all of the liquefied gas stream with at least one normally operating process pump 14 the method may further comprise subsequently turning on at least one backup pump 34 in one embodiment the method may further comprise providing that normally operating pump 14 and backup pump 34 are temporarily simultaneously on during the changing from normal operation to the backup operation in one presently preferred embodiment the method may further comprise storing at least a portion of the diverted.