The present invention relates to leak preventing gaskets contemplated for use with segmented pipe couplings, which include a pair of coupling segments adapted to receive a gasket which surrounds a pair of pipe ends to join pipes together or to join a nipple or fitting. The couplings contemplated for use with the gasket of the invention includes types adapted to attach grooved and flare end pipes, or non-grooved pipes in sealed relation to withstand fluids at temperatures up to 230° F. and higher, and at pressures of up to 1,000 psi. The ring-type gasket of the present invention is made of an elastomeric material such as synthetic or natural rubber or combinations thereof, preferably, ethylene polypropylene diene monomer, commonly referred to as “EPDM”. The gasket provides improved sealing through a pair of sealing flanges having relative planar and expansive inner walls, shorter sealing lips, and particular dimensional relationships with the grooved pipe ends. The invention also relates to a coupling incorporating such gaskets, as well as a method of providing a sealed coupling.