Experienced plumbers professionals know that the pipes must be connected to each other so that there is no leakage. If you pass the forty levels of the game Connect DD Lines, you can make any of the most complicated chains. Initially, the field contains fragments in a chaotic order. Turn each piece until you get a continuous chain. Thickening at the ends of pipes is a stub that can not be closed. To rotate it is sufficient to press the part of the pipe the required number of times until it is in the desired position.