In order to make the building facade more beautiful, indoor rainwater drainage system has been more and more widely used. Indoor rainwater pipes are generally designed according to non-pressurized flow, but because the rainwater flow is sometimes larger and more concentrated, there are two states of gravity flow and pressure flow in the pipe, so the indoor rainwater pipes are required to withstand pressure better than other drainage pipes.

PVC drainage pipe is a substitute for traditional drainage pipe, which has better physical and chemical properties. Its inner wall is smooth, and the friction resistance is less than that of conventional drainage materials, so the transverse pipe installation slope is smaller, which can improve the indoor net height of the building. At the same time,PVC drainage pipe weight is lighter, for cast iron pipe one-fifth, easy to transport and operation; Adhesive connection, easy installation and maintenance; The price is lower than the conventional drainage pipe, greatly reducing the cost of the project; Strong corrosion resistance, widely used in construction waste water and rainwater pipeline system. In addition, the widespread use of PVC drainage pipe is beneficial to save steel, which has a very important significance for alleviating the situation of our iron and steel shortage. Compared with cast iron pipe and steel pipe,PVC-U drainpipe has the disadvantages of low pressure and weak impact resistance. In addition, although PVC-U drainpipes are non-combustible materials, for indoor open-coated pipes, there is the possibility of fire spreading upward along the drainpipe.