The found present concerns a valve of the type to butterfly, with interchanging center conical log to slanted axis. A ring-like element (6) is fixed in removable way to a body valve (2), equipped of a light of income (3) and a light of escape (4), between which a having culvert is defined (5) an axis (x); The ring-like element brings solidly an estate surface (8) that is obstructed, on commando, from a stopper of the type to butterfly and that it has the form of a log of cone delimited from a conical surface, equipped of an axis (y) tilted regarding the axis of the culvert, and from two perpendicular plans to the axis of the same culvert.