Closure plug improvement

Abstract

An externally threaded closure plug for tightly closing off the internally threaded opening in shipping and storage containers such as drums, pails and the like. The plug is formed as a cup having a bottom wall and threaded cylindrical sidewall terminating in a circumferentially enlarged rim. Immediately beneath the rim of the plug is an annular gasket seat defined by the undersurface of the plug rim, the plug sidewall at the thread root diameter and an annular retaining lip lying in a plane parallel to the undersurface of the plug rim.

I claim:  
     
         1 . A closure plug formed with a cylindrical sidewall having a helical screw thread, said sidewall terminating in a circumferentially enlarged rim, an annular gasket seat immediately under said plug rim in substantial axial alignment with said screw thread root diameter and a circumferential gasket retaining lip interposed said plug gasket seat and said sidewall thread.  
     
     
         2 . The closure plug as in  claim 1 , wherein said sidewall thread runs out and terminates at a point within said retaining lip; leaving a uniform upwardly facing annular surface immediately above said thread termination.  
     
     
         3 . An externally threaded closure plug for tightly sealing off an internally threaded container wall opening, said plug formed with a cylindrical sidewall, a helical screw thread formed on said sidewall, a circumferentially enlarged rim surrounding one end of said sidewall an annular gasket seat formed in substantial axial alignment with said screw thread root diameter on said sidewall interposed said rim and said screw thread and circumferential gasket retaining means formed on said sidewall interposed said thread and said gasket seat.  
     
     
         4 . A closure plug as in  claim 3  including a sealing gasket positioned on said gasket seat.  
     
     
         5 . A closure plug as in  claim 4 , said sealing gasket being tightly confined within the radially opening annular groove formed by said rim and said gasket seat and said gasket retaining means.  
     
     
         6 . A closure plug as in  claim 3  and said gasket retaining means extending radially outwardly from said gasket seat.  
     
     
         7 . A closure plug as in  claim 6  and said gasket retaining means presenting a continuous annular surface substantially parallel to said rim.  
     
     
         8 . In combination an externally threaded closure plug and a container wall opening, said container wall opening having an internally threaded portion and an unthreaded portion, said closure plug having a cylindrical sidewall, a screw thread on said sidewall, a circumferentially enlarged rim surrounding said sidewall, an annular gasket seat formed on said sidewall, a gasket compressed between said unthreaded opening portion and said gasket seat, said gasket lying in close proximity to said internal thread and gasket retaining means on said plug sidewall interposed said plug thread and said gasket seat preventing interengagement of said gasket and said opening internally threaded portion whereby unimpeded unscrewing of said plug and gasket as an undisturbed unit is effected.  
     
     
         9 . The combination as in  claim 8  wherein said container wall unthreaded portion extends upwardly and radially outwardly from said gasket retaining means.  
     
     
         10 . The combination as in  claim 8  and said sealing gasket being tightly confined by said rim and said gasket retaining means.  
     
     
         11 . The combination as in  claim 10  and said gasket retaining means presenting a continuous annular surface substantially parallel to said lip rim.  
     
     
         12 . The combination as in  claim 11  and said gasket retaining means extending radially outwardly to a point spaced from said opening unthreaded portion.