Fluid circulation valve (10) is provided for use with a well drilling operation, so that a drill joint may be added to or removed from the drill string while continuously circulating fluid into the well. Valve housing (12, 18) has a central flow path therein, a housing side port (87), and upper and lower threaded connectors for engagement with the drill joint and the drill string, respectively. A rotatable ball (30) is positioned within the flow path in the valve housing and a port (87) in the ball is in fluid communication with the housing side port (15) when the ball is closed. A coupling (60) is provided for engaging the valve housing and sealing between an interior of the valve housing and the radially external flow line, which passes fluid into the well when a drill joint is being connecting to the upper end of the valve.