A firesafe bidirectional floating ball valve comprising: a housing; first and second annular seats that hold between them a ball that is rotatable to open and close the valve to fluid flow; an annular spring on one side of the ball that operates to seal both of the seats to the ball; and an annular ridge coaxial with the first seat; wherein with the valve closed, net pressure on the ball in a direction from the second fluid flow port to the first fluid flow port operates to displace the ball and apply force to the first annular seat that closes a narrow clearance space between the ball and the first annular seat.