A product transfer valve (1) includes a valve body (3), an inlet port (2), an outlet port (18). A safety interlock mechanism includes a segmented collar (22) with internal threads (23) for mounting the valve to a connection. A safety collar (6) is axially movable between a valve open position and a valve closed position, and causes movement of the segmented collar. An interference member (12) engages the safety collar (6) to prevent inadvertent radial outward movement of the internal threads on the segmented collar until the safety collar is moved to the valve closed position.