section sleeve insert 22 and its support member counter bore 38 have uniform concentric configurations optionally each can have abutting vertical linear channels 48 which have parallel axes and are adapted to admit a linear rigid key of rectangular cross section 50 that serves as a brake against sleeve agitation with the member by the intermittent torque forces which are exerted upon engaged bolt 26 bolt 26 is shown in threading engagement an intermediate position with sleeve 22 in fig2 as noted rotation of the bolt 26 is accomplished by insertion of a typical torque tool screwdriver into exposed bore hole 13 to engage the notch not seen on the head of the bolt 26 the axially aligned lower lug 34 of the bolt 26 is seen in compressive contact with gasket 18 on vessel lip 16 since the vessel cover 10 is usually hinged at one point along its periphery not shown the vertical position of bolt 26 relative to that of fixed position sleeve 22 determines the degree of compressive force being exerted upon gasket 18 in fig3 an underside perspective view of the assembled closure components 20 is presented better depicting the inner edge of o ring retainer 28 disposed adjacent lower planar surface 42 of the sleeve 22 the degree of downward projection of bolt 26 and its lug 34 is readily varied as has been described thus varying the resulting compressive force.