A ball valve is provided. The ball valve includes at least one load varying mechanism provided in the static body assembly. The load varying mechanism includes a biasing member pressing one of the ball seat seals against the outer surface of the ball of the ball valve with a variable sealing load force applied on the ball, toward the ball and coaxial with the direction of the fluid. The load varying mechanism also includes a movable member operatively connected to a cam and to the biasing member, a rotation of the cam translating the movable member coaxially to the direction of the fluid, in order to variably load the biasing member toward or away from the ball, based on the different positions of the ball.