Calcium, magnesium and other carbonate, sulfate and their solid suspended substances as well as chemical and electrochemical corrosion products (such as rust) are the material basis of pipe inner wall scaling. The inner surface of copper pipe is rough and not smooth, including the roughness of inner wall of copper pipe and the spots and small holes caused by corrosion during processing, which create the conditions for the deposition and scaling of these substances. Different from general substances, the solubility of carbonate decreases with increasing temperature, resulting in salt precipitation and increased deposition. At the same time, the higher the temperature, the faster the corrosion reaction of the pipeline, the more corrosion products, also accelerate the scaling. The production process of the radiator copper tube is cold-drawn seamless copper tube, which is not only smooth and clean, but also has the function of killing microorganisms. The precipitated particles formed by calcium and magnesium ions can not be attached to the wall of the copper tube. Therefore, in the metal pipe, the copper tube is very difficult to scale. Other metal conduit is different as a result of production technology, inner wall is not very smooth, can produce to knot scale phenomenon differently, copper tube and stainless steel tube want to compare steel tube and galvanizing steel tube much better. The ship's steel plates are usually coated with copper to prevent seawater microbes from settling on them and affecting the ship's speed. As is known to all, copper pipe has excellent resistance to high and low temperature changes. Copper tube can be between -200℃ to 200℃ temperature conditions, to ensure that no bending phenomenon, no deformation, in the open fire does not burn, in the heat will not release toxic gas, in the range of extreme temperature of cold and hot water, heat resistance is very good.
The influence of temperature change (δ T) on the service performance of hot water pipeline mainly lies in the characteristics of thermal expansion and cold contraction and creep fatigue. In this respect, the coefficient of thermal expansion of plastic pipe is larger, in the hot water pipe between water supply, water cut-off, the coefficient of thermal expansion of plastic pipe is ten times that of copper pipe. Of course, any kind of pipe has the phenomenon of heat expansion and cold contraction, copper pipe is no exception, but relative to the pipe of other material, linear expansion coefficient is much smaller. The linear expansion coefficient of copper tube is 0.018mm/m· K. When the temperature rises 60℃, the copper tube of 1m length will increase by 1mm. In a linear pipe section of a certain length, thermal stress will occur in the pipe due to temperature rise, resulting in the destruction of the pipe interface or support. Under normal circumstances, it is required to take corresponding measures in every 10m long straight pipe section, such as installation of expansion joints, during engineering installation. However, under normal circumstances, the straight pipe section generally does not exceed 10m. According to the practical experience of pipeline construction and installation of heating system in a residential building of the PEOPLE's Liberation Army, in order to ensure the safety of the installation of hidden heating and hot water pipes, plastic or other materials of elbow pipe sleeve should be added at each elbow. If the open-mounted pipeline is not more than 10m, it is unnecessary to consider the problem of expansion.
