Removable closure and method

Abstract

A removable closure for blocking an opening able to resist high forces is formed by a plug assembly installed in a receptacle located over the opening, the receptacle including a smaller bore at the beginning of the receptacle and a larger bore adjacent thereto, these bores together forming an inwardly extending rim and an adjacent groove, with opposite radial clearance openings extending axially through the rim. The plug assembly includes two oblong plates mounted on a plug member, a first oblong plate threaded onto an intermediate threaded section of the plug member, a second oblong plate fixed to the end of the plug next to the first oblong plate in a crosswise orientation. The plug member is rotated to align the two oblong plates in preparation for insertion into the receptacle, and the ends thereof are then inserted into the clearance openings to position the second oblong plate entirely within the groove while leaving the first oblong plate ends interfit within the clearance openings. The plug member is rotated back to retighten the threaded engagement with the first oblong plate and to orient the second oblong plate within the groove crosswise to the first oblong plate and located behind one side of the rim to be able resist high forces exerted thereon without loading the threaded connection.

1 . A removable closure for blocking an opening into a chamber capable of resisting high forces exerted thereon, comprising: 
 a plug assembly including an elongated plug member having a threaded intermediate section engaging a threaded bore centrally located in a first oblong plate included in said plug assembly,    a second oblong plate also included in said plug assembly affixed to an end of said plug member;    a receptacle located at the entrance to a chamber to be closed, said receptacle including a bore of a diameter smaller than the length of said oblong plates at the entrance of said receptacle, and an adjacent inner bore of a larger diameter able to receive said second oblong plate, said bores together forming an inwardly extending rim adjacent the entrance to said receptacle and a groove adjacent said rim;    said second oblong plate configured to be rotatable in said groove;    a pair of opposite clearance spaces formed extending through said rim and into said groove, allowing said oblong plates to pass crosswise through said spaces and said inner bore within said rim when aligned therewith, said second oblong plate rotated therein into a crosswise orientation with respect to said first oblong plate which is configured to be fit to said spaces to be held against rotation, said rotation also tightening said threaded engagement of said first oblong plate on said threaded intermediate section on said plug member to create a frictional lock preventing rotation of said plug member relative said first oblong plate, thereby in turn preventing rotation of said second oblong plate into alignment with said spaces, said second oblong plate abutted against said rim to absorb said high forces.    
   
   
       2 . The removable closure according to  claim 1  further including a locking washer received over said plug adjacent said threaded section and section seated on a shoulder adjacent said locking washer, tightened into frictional locking engagement therewith by advance of said plug member into said threaded bore in said first oblong plate.  
   
   
       3 . The removable closure according to  claim 1  wherein said second oblong plate has rounded ends facilitating rotation thereof in said groove.  
   
   
       4 . The removable closure according to  claim 1  wherein said clearance spaces comprise slots each extending radially out in opposite directions from said first bore, said ends of both of said oblong plates able to be inserted therein.  
   
   
       5 . The removable closure according to  claim 1  wherein said plug member has one or more wrenching surfaces adjacent an end opposite said end affixed to said second oblong plate.  
   
   
       6 . A method of blocking one end of a chamber in a structure with a plug assembly so as to resist high forces applied to said plug assembly while enabling ready removal of said plug assembly comprising: 
 providing a receptacle at an entrance to said chamber formed with a smaller diameter bore and an adjacent larger diameter bore, said bores together form an inwardly extending rim at the beginning of said receptacle adjacent to a groove;    forming one or more radial clearance openings extending through said rim;    forming aid plug assembly by threading a first oblong plate onto an intermediate threaded section adjacent one end of a plug member included in said plug assembly tightly against an axially fixed surface adjacent thereto to create a frictional lock of said first oblong plate to said plug member;    assembling a second oblong plate onto said one end of said plug member and fixing the same thereto in a crossing orientation with respect to said first oblong plate, both of said oblong plates being configured to pass crosswise through smaller diameter bore when aligned with said spaces, said second oblong plate rotatable in said groove;    counterrotating said plug member and attached second oblong plate to align said oblong plates with each other and loosen said threaded engagement of said first oblong plate with said plug member;    inserting said aligned oblong plates into said clearance openings to position said second oblong plate entirely within said groove with ends of said first oblong plate disposed within said clearance openings, interfitting the same therein so as to prevent rotation thereof;    rotating said plug member to again position said second oblong plate crosswise to said first oblong plate and to retighten said threaded engagement, whereby    said second oblong plate is positioned against one side of said rim to resist said high forces exerted thereagainst, and is prevented from rotating into alignment with said clearance opening by interfitting of the ends of said first oblong plate within said clearance openings and by said frictional locking of said first oblong plate to said plug member.