A valve seating (23) is made from a fluoridated polymer, for example, solid glass-coated PTFE or reinforced PFA. At least one electrode (24) is attached to or integral with the valve seating and made of conductive material, such as graphite-TEFLON.RTM., that is compatible with the valve seating. The valve seating is especially for use in conjunction with a device for verifying the integrity of an enamel coating of the "enamel-test" type. The valve seating is then used on the waste valve (11) of the container to be checked and two electrodes (24) are disposed so as to be in contact with the contents (8).