Used to transport water, oil, gas and other fluids. Concrete pipes are divided into four categories: plain concrete pipes, ordinary reinforced concrete pipes, self-stressed reinforced concrete pipes and prestressed concrete pipes. According to the different inner diameters of concrete pipes, they can be divided into small-diameter pipes (with inner diameter below 400 mm), medium-diameter pipes (400-1400 mm) and large-diameter pipes (above 1400 mm). According to the different capacity of the pipe to withstand water pressure, it can be divided into low pressure pipe and pressure pipe. The working pressure of the pressure pipe is generally 0.4, 0.6, 0.8, 1.0, 1.2 MPa, etc. Compared with the steel pipe, the concrete pipe can be divided into flat mouth pipe, socket pipe and tongue and groove pipe according to the different types of pipe joints. The interface forms include cement mortar trowel interface, wire mesh cement mortar trowel interface, cement mortar socket and rubber ring socket, etc.