Closure construction having backup support means

Abstract From the Canadian patent

A closure and boss combination for providing an internally threaded outlet in a drum end includes a raised metal boss formed in the drum end and configured with a pair of concentric axially extending annular walls connected by an annular ring-shaped top surface. Securely crimped within the raised metal boss is a synthetic material closure which includes an internal series of threads surrounded by a crimping flange which includes on its outer diameter surface a series of serrations configured with alternating recesses and protruding portions. The flange includes an interior support surface which is substantially concentric with the outer surface of the serrations and the inner, axially …