A transfer valve assembly (10) for use as a feed valve or a discharge valve includes a series of open-faced pockets (46) biased by leaf springs (48) off of a central hub (44) and an arcuate saddle piece (22) mounted at an opening (14) of a sterilizer vessel (12) for transferring containers from an infeed conveyor (34) onto an interior reel (18). The engagement of open-faced pockets (46) with saddle (22) creates a seal to prevent the escape of steam, but gaps are provided between pockets (46) which allow for a controlled escape of steam in a manner that allows the pressure within the sterilizer vessel to be maintained at a slightly elevated level.