Radial compression gasket

Claim 1

A gasket for coupling grooved end pipe in end-to-end relationship comprising, in combination, an annular gasket member formed of resilient material having a transverse cross section including a base, lateral leg portions and a central portion intermediate said leg portions, said base and leg portions having outer cylindrical and conical coupling recess engaging surfaces, respectively, said leg portions each including an annular lip surface adapted to engage a pipe circumference intersected by an inner leg portions surface disposed toward said central portion, said central portion including an innermost bulbous convex surface merging from slope surfaces each in a spaced opposed relationship to an inner leg portion surface when said gasket is in a relaxed non-compressed condition whereby opposed inner leg portion and slope surfaces define annular cavities, said leg portions deflecting toward said central portion upon engaging a pipe circumference and the configuration of said opposed inner leg portion and slope surfaces being substantially planar in transverse cross section and of substantially equal radial length and intersect to define a first acute included angle when said gasket is in the relaxed state whereby compression of said gasket central portion in use engages said opposed inner leg portion and slope surfaces to completely eliminate said cavities and extrudes said central portion between the opposed ends of the pipe being coupled, said central portion bulbous convex surface being of such configuration and dimension to define a radial compression sealing surface on the pipes' circumferences adjacent the ends thereof to seal the regions of said engaging inner leg portions and slope surfaces.