| 摘要 |
An improved ball valve (1), in particular for gas systems, comprises a tampering indicating seal (25) made by injection molding a synthetic or metal material into cavities (19; 21; 22) formed in the screw-clamping nut assembly (11, 13) and including a cap outer portion (29) which substantially covers the surface of the outer face of the nut (13) and/or extending (29A) on the side surface or said nut (13).
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