Abstract: A hydraulic coupling device for drawing and connecting two pipe flanges together, comprising a pair of clamps one of which is adapted for bolting the coupling device to one of the pipe flanges, and the other of which is movable towards and away from the first clamp by actuation of a hydraulic motor. An externally threaded spindle is connected to the motor and extends through an internally threaded bore in a sleeve on which the movable clamp is mounted, so that actuation of the motor causes the sleeve and movable clamp to slide lengthwise in the body bore as the spindle rotates. When the motor is reversed, the movable clamp swings radially away from the pipe to facilitate disconnecting the two pipe flanges. The coupling device also includes a hydraulic bypass switch to disable the hydraulic motor when the movable clamp arrives at a predetermined position.