Sealing microsawtooth ring joint of two opposing surfaces

A closing joint of parallel gate valves which include two seat rings mounted in the valve body and a gate slab or disc slidable therebetween to form a fluid controlling passage or to provide a fully open position when the gate is slid to where a opening portion of the gate slab is aligned with the valve passage or the gate disc is fully off the valve passage and a fully closed position when a blind portion of the gate slab or the gate disc is aligned with the valve passage, comprising;

• a jointing end surface (called a toothed surface) per the seat ring and two parallel jointing surfaces (called plain surfaces) of the gate slab or disc used to form two identical closing joints, wherein there is such one or more microsawtooth rings on each toothed surface pressed tight on each plain surface as to form a jointing microcosmic line contact followed by a surface contact protecting the line contact thereon from disappearing, the toothed surfaces are of a full flat or of a raising annular flat and wherein the crest of the microsawtooth ring is a cutting edge whose corner or whose crest angle is about 90°˜120°, the tooth height Z1 of the microsawtooth ring is about 10˜20 times the roughness Ra of the seated surface or the plain surface, and the ratio of the tooth pitch Xs to the tooth height Z1 of the microsawtooth ring equals 20˜500 to provide for the toothed surface fastened tight on the plain surface a microcosmic line contact followed by a surface contact protecting the line contact thereon from disappearing.