Abstract: A container closure especially for large containers and having circumferentially spaced tool access regions in a rim flange for insertion of a removal tool. These access regions are located between a base of the flange and a locking bead. Between the access regions, sections of a discontinuous locking bead extend around the inside of the flange, the bead being discontinuous across the circumferential area occupied by the access regions to enable a removal tool to be inserted downwardly through the access regions and between bead sections. Rim stiffening protrusions project from the outer surface of the flange beneath the access regions and across the circumferential line of the locking bead to stiffen the flange to prevent it from splitting when a removal tool is inserted down through the access regions and between bead sections.

Abstract: In a container and closure assembly, there is a resilient seal between the two components and the resiliency of the seal determines the normal relative closed positions of the closure and container. When the assembly is included within a stack, there is movement of the closure in the closing direction further to compress the seal. To prevent over-compression of the seal, opposed movement limiting surfaces are provided upon the closure and container, these surfaces being slightly spaced normally, but closing together to take loads directly from closure to container and thus avoid overloading the seal, when the assembly is located in a stack.

Abstract: A plastic closure with a U-shaped rim surrounding a closure portion, an upper wall of the rim extending both upwardly and downwardly from the closure portion and flaring outwardly away from the closure portion. The upper end of the inner wall joins into the base of the `U` shape and the lower end is resiliently flexible. When fitted to a container, upper and lower ends of the inner wall seal against the lip and inner surface of the wall of the container, resiliency of the inner wall of the closure ensuring its sealing engagement with the container wall.

Abstract: A method of polymerizing and a polymerization column for a monomeric vinylidene compound in which heat exchange tubes are spaced relatively along a polymerization chamber, each tube lying in a radial plane of the chamber and having an ingoing length and an outgoing length, the two lengths being in the form of windings with the windings of each length lying between windings of the other.

Abstract: A container and closure in which the closure has an inverted U-shaped rim and a cover portion lying within the rim and joined to the inner wall of the closure rim at a position downwards from the base of the `U`. The shape and size of the container rim is such that when the closure is assembled to it, the inner wall of the closure rim is resiliently flexed inwardly about its junction with the cover portion which is thereby resiliently flexed downwards. The inner wall thus is flexed and twisted to seal against the inner surface of the container rim and applies a positive pressure to assist in sealing. In preferred constructions, the inner wall has an extension below the cover portion. The extension flexes outwards during flexing of the cover portion so as to increase the seal.

Abstract: A closure and container in which the closure has an axial flange which cooperates with the container to lock the closure in closed position, the closure also having an annular recess accommodating a resilient seal for sealing against the container rim. The seal projects from the recess before assembly of closure to container. During assembly, the container compresses the seal into the recess until in the fully closed position, the container engages a seating surface upon the closure, at which point the seal is only partially compressed.