The present invention describes a method of isolating a section of rough bore flexible pipe (1), said method including the steps of deploying a sealing device (10) into the pipe to the required position and forcing a sealing solution through the carcass (2) of the flexible pipe to seal the space between the sealing device and the internal pressure sheath (5) of the flexible pipe and also a sealing device (10) for isolating a section of a rough bore flexible pipe, said apparatus comprising means for anchoring the sealing device in the pipe and means for sealing the device in the pipe, said sealing means comprising means for forcing a sealing solution through the carcass of the pipe.