Patent ID: 6840549

Claim:
In combination: a hollow riser leading to an underground liquid storage tank, said riser having a riser liquid passageway, an externally threaded upper riser end with external tapered threads and an upper rim defining a riser opening communicating with said riser liquid passageway; a structure disposed above said riser, said structure defining a structure interior and having a lower, open structure end communicating with said structure interior, said structure further having internal straight pipe threads extending upwardly from said lower, open structure end and terminating at an inwardly projecting shoulder of said structure; an annular seal in fluid-tight engagement with said inwardly projecting shoulder above the internal straight pipe threads of said structure; and a threaded riser adaptor of integral construction having an upper externally threaded riser adaptor portion including external straight pipe threads in threaded engagement with the internal straight pipe threads of said structure and forming a first liquid-tight seal therewith and a lower internally threaded riser adaptor portion including internal tapered threads receiving the external tapered threads of said externally threaded upper riser end and securing the threaded riser adaptor to said riser, said threaded riser adaptor defining a riser adaptor liquid passageway communicating with both the riser liquid passageway and the structure interior to allow the flow of liquid therebetween, and the external tapered threads of said externally threaded upper riser end and the internal tapered threads of said lower internally threaded riser adaptor portion being in fluid-tight engagement and forming second liquid-tight seal therebetween without the upper rim of the riser abutting against the threaded riser adaptor, said upper externally threaded riser adaptor portion having a distal end surrounding the riser adaptor liquid passageway, said distal end being circular-shaped and having a smooth bearing surface bearing against said annular seal and in fluid-tight relationship therewith, said threaded riser adaptor and seal cooperable to maintain a fluid-tight interconnection between said riser and said structure even if the riser is damaged or irregular at or closely adjacent to the rim thereof.