Steel pipes include ordinary steel pipes, galvanized steel pipes and seamless steel pipes. Ordinary steel pipes are used for non-drinking drinking water pipes or general industrial water supply pipes. The surface of the steel pipe is galvanized (produced by hot-dip galvanizing) to prevent rust and corrosion, so as not to affect the water quality. It is suitable for drinking water pipes or some industrial water pipes with high water quality requirements; seamless steel pipes are used for high-pressure pipe networks. , its working pressure is above 1.6MPa. The connection methods of steel pipes include threaded connection, welding and flange connection. Threaded connections are connections using threaded pipe fittings. Most of the accessories are made of malleable cast iron, galvanized and non-galvanized, which have high corrosion resistance and mechanical strength. There are few steel fittings at present. Galvanized steel pipes must be threaded, and their fittings should also be galvanized fittings. This method is mostly used for exposed pipes. Welding is the use of welding machines and electrodes to weld two sections of pipes together. The advantage is that the joint is tight, no water leakage, no accessories are required, and the construction is fast. But cannot be disassembled. Welding is only suitable for non-galvanized steel pipes. This method is mostly used for concealed pipes. Flanges are connected to pipes with larger diameters (above 50m), and the flanges are often welded (or threaded) at the pipe ends, and then the two flanges are connected together with bolts, and then the two sections of the pipe are also connected together. Flange connections are generally used to connect valves, check valves, water meters, pumps, etc., as well as pipe sections that require frequent disassembly and maintenance.
