| 摘要 |
A butterfly valve designed primarily for piping systems in which corrosive fluids are circulated at high temperature comprises a pivotally mounted disc having a convex annular edge portion associated with an annular seal which projects within the valve passage. The seal is formed by a specially shaped removable metallic ring coated with plastic material and having a flared cylindrical mouthpiece which is applied in fluid-tight contact with the edge portion of the valve disc and held in position within the valve passage by a retaining ring.
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