Abstract: A closure (12) for a beverage keg (10) for the pressurised delivery of a beverage, the closure comprising: a valve housing (38) comprising a valve housing wall (32) and an inlet and configured to house a valve (26) for controlling a flow of pressurised gas through the inlet into a headspace of the beverage keg (10); a venting aperture (27) in the valve housing wall, separate from the inlet and arranged to vent the headspace of the beverage keg; and a barrier (29), integrally formed with the valve housing wall and arranged to seal the venting aperture (27) such that the closure (12) is able to retain the pressurised gas within the keg when the closure is arranged in an unvented configuration, the barrier (29) being configured to rupture due to internal pressure from within the keg in order to switch the closure into a vented configuration in which the venting aperture (27) is no longer sealed by the barrier, wherein the barrier is formed as a geometrical shape having a barrier diameter or a barrier width in th