Method for laying cable in pressure pipeline without stopping transmission

A method of laying a cable in a pipeline without stopping transmission of a medium through the pipeline, the method comprising:

• arranging an upstream bypass at an upstream valve on the pipeline and a downstream bypass at a downstream valve on the pipeline, wherein a first downstream bypass valve and a second downstream bypass valve are arranged on the downstream bypass, and a first upstream bypass valve and a second upstream bypass valve are arranged on the upstream bypass, the first upstream and downstream bypass valves being located closer to the pipeline than the corresponding second upstream and downstream bypass valves, the downstream bypass being located at a bottom of the pipeline;
• wherein the upstream valve is located at a junction of the upstream bypass and the pipeline, and the downstream valve is located at a junction of the downstream bypass and the pipeline;
• arranging a pay-off reel in the upstream bypass and a take-up reel in the downstream bypass;
• arranging a floating ball in the upstream bypass, wherein the floating ball is hollow, a stowed section of a traction rope having a length of two meters being stored within and connected to the floating ball;
• opening the second upstream bypass valve and placing the floating ball in the upstream bypass, a tail end of the traction rope being connected with the cable, the traction rope and the cable being wound on the pay-off reel;
• closing the second upstream bypass valve, and then opening the first upstream bypass valve, so that the floating ball enters the pipeline and moves forward in the pipeline under an action of a fluid pressure difference of the medium in the pipeline, thereby dragging the traction rope and/or cable from the pay-off reel into the pipeline, and extending the traction rope and/or the cable within the pipeline;
• enabling the floating ball to move to a position of the downstream bypass under the action of the fluid pressure difference in the pipeline, such that, because the downstream bypass is located at a bottom of the pipeline, the floating ball falls into the downstream bypass under a weight of the floating ball;
• opening the first downstream bypass valve, so that the floating ball falls to a location between the first downstream bypass valve and the second downstream bypass valve;
• closing the first downstream bypass valve and opening the second downstream bypass valve;
• taking out the floating ball from the downstream bypass, and pulling out the stowed section of the traction rope stored in the floating ball;
• enabling the traction rope to pass through a sealing device arranged on the second downstream bypass valve, then pulling a portion of the traction rope out of the second downstream bypass valve and closing the second downstream bypass valve;
• and
• pulling all the traction rope out of the downstream bypass until a head of the cable is pulled out of the downstream bypass, thereby completing a whole process of laying the cable into the pipeline.