safety valve assemblage comprises an annular structure 30 which is insertable in the bore of the tubular element 20 immediately below an inwardly projecting shoulder 20b such annular structure is axially slotted to permit the pivotal mounting of flapper valve fv fig1 c on a pin 32 traversing the side wall of the assemblage 30 assemblage 30 also defines an annular valve seat 32a which cooperates with the upwardly facing peripheral edge 35 of the flapper valve fv the annular structure 30 is further provided with an o ring seal 30a which cooperates with the internal bore of the tubular body element 20 the safety valve assemblage 30 is held in position by the upwardly facing end 24a of a connection sub 24 connection 24 is secured to the bottom end of the tubular body element 20 by threads 24b and such threads are sealed by an o ring 24c the lower end of connection sub 24 is provided with reduced diameter external threads 24d which are engagable with the top end of any conventional hurricane plug hp which can be set by rotation in a selected direction generally rotation to the right followed by the application of a setdown weight since such hurricane plugs are well known in the art further description of the plug.