A method of severing tubular members using an expandable linear explosive shape charge positioner. The method involves placing a plurality of arc-shaped charge chambers along the same plane and adjacent to the interior walls of a tube. Simultaneous detonation of the charge chambers severs the tube along a common plane. The positioner is placed within a tubular member and includes a remotely extendible framework with linear explosive shape charges enclosed therein. When in the collapsed position, the apparatus passes through constrictions within the tubular members. When extended, the framework is positioned transversely to the axis of the tubular member with the shape charges positioned adjacent the interior walls thereof. Shape charge chambers with angled ends are presented to provide overlap when the device is fully extended to better ensure complete separation of the tubular member at the discontinuities of the shape charges about the plane of severance.