Brønnproduksjonsrørventil og fremgangsmåte for styring av fluidstrøm

A well tubing valve including a substantially tubular body connected in a tubular string and a rotational valve member having at least one aperture. The valve member is a sleeve having a part spherical surface, is rotationally moveable relative to the body to align and misalign the at least one aperture in the valve member with a port in the body. The valve member is actuable to rotate relative to the body in a single direction, and moves from the open position to a closed position and back by rotation in the same sense. The valve also includes a sealing arrangement adapted to provide a metal seal that is biased to seal against the part spherical surface.