A closure body (40) is provided for installation with a liner membrane (52) on a container (44). The closure body (40) has a peripheral portion (74) for being mounted on the container (44) around an access opening (48), and a separable portion (82) that (i) is disposed laterally inwardly of the peripheral portion (74); (ii) is initially connected to the peripheral portion (74) by at least one frangible connection (86); and (iii) can be separated from the peripheral portion (74) upon breaking of the at least one frangible connection (86).