Steel pvc ball valve pipes include ordinary steel pipes, galvanized steel pipes and seamless steel pipes. Ordinary steel pipes are used for non-domestic drinking water pipes or general industrial water supply pipes. Galvanized steel pipe surface (produced by hot-dip galvanizing process is to prevent rust and corrosion, so as not to affect 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 connection is to use threaded pipe fittings to connect. Most of the accessories are made of malleable cast iron, which are divided into galvanized and ungalvanized, and their corrosion resistance and mechanical strength are relatively high.
There are currently fewer steel parts. Galvanized steel pipes must be connected by threads, and their fittings should also be galvanized fittings. This method is mostly used for surface installation of pipelines. Welding is to use a welding machine and welding rod to connect two sections of pipelines together. The advantages are tight joints, no water leakage, no accessories, and rapid construction. But it cannot be disassembled. Welding is only suitable for non-galvanized steel pipes. This method is mostly used for concealed pipelines. The flange is connected to a pipe with a larger pipe diameter. The flange is often welded or threaded on the pipe end, and then the two flanges are connected together with bolts, and the two pipes are also Connected together. Flange connections are generally used to connect valves, check valves, water meters, water pumps as well as pipe sections that need to be frequently disassembled and overhauled.
The most commonly used water supply plastic pipes are water supply unplasticized polyvinyl chloride pipes and water supply polypropylene pipes . In addition, there are polyethylene pipes, which are suitable for conveying water with a temperature not exceeding . The relevant standards follow the requirements of Pipes for Water cross-linked polyethylene pipe, suitable for conveying water at a temperature of . They all have strong chemical stability, corrosion resistance, and are not subject to acid, alkali, salt, oil and other media Corrosion, smooth pipe wall, good hydraulic performance, light weight, easy processing and installation. But the common shortcomings are poor temperature resistance and low strength.
Therefore, it is also subject to certain restrictions in use. Water-hardened polyvinyl chloride pipe , the temperature of the conveying water does not exceed pipes generally adopt socket connection, in which socket bonding is suitable for pipe outer diameter 20～1601m; rubber ring connection is suitable for pipe outer diameter greater than or equal to with metal pipe fittings The connection of valves, valves, etc. adopts threaded or flanged connection. Water supply polypropylene pipe is suitable for system working pressure not greater than 0.6Mpa and operating temperature not greater than 70℃. Water supply polypropylene pipe uses hot melt socket connection. When connecting with metal pipe fittings, polypropylene pipe fittings with metal inserts are used as a transition. The pipe fittings and polypropylene pipes are connected by hot-melt sockets, and the metal pipe fittings are connected by threads.
