The selection of water supply and drainage pipeline valves and the advantages and disadvantages of various valves Do chemical pipeline valves need bypass valves when they are installed

The selection of water supply and drainage pipeline valves and the advantages and disadvantages of various valves Do chemical pipeline valves need bypass valves when they are installed

Common building water supply and drainage pipes are mainly plastic pipe, metal pipe and composite pipe three kinds. But far beyond these categories, there are many new types of tubing.
1, steel pipe
Steel 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 (using hot dip galvanized process production) is to prevent rust and corrosion, so as not to affect the water quality, suitable for drinking water pipes or some industrial water pipes with high water quality requirements; Seamless steel pipe is used in high pressure pipe network, and its working pressure is above 1.6MPa.
The connection methods of steel pipe are threaded connection, welding and flange connection. Threaded connections are made using threaded pipe fittings. Parts are mostly made of malleable cast iron, divided into galvanized and non-galvanized two, its corrosion resistance and mechanical strength are greater. Steel fittings are few at present. Galvanized steel pipes must be connected with threads and their fittings shall also be galvanized fittings. This method is often used in open pipe. Welding is the use of welding machine, welding rod burning welding to connect two sections of pipe together. The advantages are tight joint, no water leakage, no accessories, rapid construction. But you can’t disassemble it. Welding is only applicable to steel pipes that are not galvanized. This method is mostly used for hidden pipe.
The flange is connected to the pipe with a larger diameter (above 50m), and the flange is usually welded (or threaded) at the pipe end, and then the two flanges are connected together with bolts, and then the two sections of the pipe are connected together. Flange connection is generally used in the connection of valves, check valves, water meters, water pumps and other places, as well as the need for frequent disassembly, maintenance of the pipe section.
2, water supply plastic pipe
** The commonly used plastic pipes for water supply are hard polyvinyl chloride pipe (UPVC) and polypropylene pipe (PP pipe). In addition, there are polyethylene (PE) pipe, suitable for conveying water temperature does not exceed 40℃, the relevant standards follow the provisions of “Polyethylene (PE) pipe for water supply” GB/T13663; Crosslinked polyethylene (PE-x) pipe: polybutene (PB) pipe, suitable for conveying water temperature of 20″–90℃. They have strong chemical stability, corrosion resistance, not acid, alkali, salt, oil and other media erosion, smooth wall, good hydraulic performance, light quality, easy processing and installation. But the common disadvantages are poor temperature resistance and low strength. Therefore, it is also limited in use.
A hard polyvinyl chloride (UPVc) pipe is used to deliver water at a temperature not exceeding 45 ° C. Generally, UPVC pipes are connected by socket connection, and the socket bonding is suitable for pipe outer diameter of 20~1601m. Rubber ring connection is suitable for pipe diameter greater than or equal to 63mm; The connection with metal pipe fittings, valves, etc., shall be threaded or flanged.
Polypropylene water supply pipe (PP pipe), suitable for the system working pressure is not greater than 0.6Mpa, working temperature is not greater than 70℃. Polypropylene pipe for water supply is connected by hot melt socket. When connecting with metal pipe fittings, polypropylene pipe fittings with metal inserts are used as the transition. The pipe fittings are connected with polypropylene pipe by hot melt socket, and are connected with metal pipe fittings by thread.
3, PVC tube
Electrical threading pipe and drainage pipe.
4, brass
The copper pipe and its accessories have complete varieties and specifications, large diameter range, can be selected from 6mm to 273mm. Copper pipe is easy to bend, easy to process, easy to change shape, can meet the engineering installation of pipeline wiring and interconnection of all needs. Especially in the field construction, the temporary cutoff, bending and grinding of copper pipe are easy and free. All kinds of pipes and accessories can be assembled and transported to the site, or can be temporarily installed on the site l, the effect is satisfactory.
Copper is a hard metal that corrodes. Can be used in a variety of environments without damage. According to the history of use abroad, the service time of many copper pipes has exceeded the service life of the building itself. Therefore, copper water pipe is the most safe and reliable water pipe.
Copper is a red metal with a green face. Copper inhibits bacterial growth and keeps drinking water clean. Copper dining utensils have a long history, non-toxic and tasteless.
Copper pipes and fittings can maintain their shape and strength under high temperature and pressure, and there will be no long-term aging phenomenon.
Copper pipe has a thick hard layer of protection, neither oil, carbohydrates, bacteria and viruses, harmful liquids, air or ultraviolet light can pass through it and can not erode it and pollute the water. Parasites cannot inhabit copper surfaces. But the high price of copper pipe is its big disadvantage, is the current high quality water pipe.
5. Composite tube
With the continuous development and improvement of technology of industry in our country, new materials and new technics were adopted in water supply and drainage engineering, and composite piping has been used extensively in water supply and drainage engineering.
(1) aluminum-plastic composite pipe
The middle layer of the aluminum-plastic composite pipeline is made of welded aluminum tube, and the outer layer and inner layer are made of medium density or high density polyethylene plastic or crosslinked high density polyethylene, which is combined by hot melt adhesive. The pipe not only has the pressure resistance of metal pipe, but also has the corrosion resistance of plastic pipe. It is an ideal pipe used for building water supply. Aluminum plastic composite pipe is generally crimped by screw card sleeve, its accessories are generally copper products, it is the first accessories nut set in the pipe end, and then the inner core of the accessories into the end, and then use a wrench to tighten the accessories and nut can be. Good high temperature resistance, convenient construction, improve the labor efficiency. The long-term thermal expansion and cold contraction of the pipeline will cause the dislocation of the pipe wall resulting in leakage. The aluminum-plastic pipe is liable to burst under pressure. In the area where the decoration concept is relatively new, the aluminum plastic pipe has gradually lost the market and belongs to the eliminated product.
(2) steel-plastic composite pipe
Steel-plastic composite pipe is a pipe lined (coated) with a certain thickness of plastic composite. Generally divided into lined plastic steel pipe and coated plastic steel pipe two. Steel-plastic composite pipe is generally connected with thread, and its accessories are generally steel-plastic products.
6, thin wall stainless steel pipe
With the development of national economy and the improvement of people’s living standard, thin-walled stainless steel water pipe and stainless steel pipe fittings have become a new trend in the development of domestic water supply pipe system. Meet the health requirements of the thin-walled stainless steel pipe will not cause secondary pollution to the water quality, to meet the national direct drinking water quality standards.
Thin-walled stainless steel pipe is a completely recyclable water pipe, and will not leave future generations with garbage that cannot be disposed of.
The strength of the thin-wall stainless steel pipe material is higher than all the water pipe materials, greatly reducing the possibility of water leakage affected by external force, and saving a lot of water resources.
Thin-wall stainless steel pipe has excellent corrosion resistance, no scaling in the long-term use process, the inner wall is smooth and clean, low energy consumption, cost saving, is a relatively low conveying cost of water pipe material.
The thermal insulation performance of the thin-walled stainless steel pipe is 24 times that of the copper pipe, which greatly saves the geothermal energy loss in the hot water transmission.
Thin wall stainless steel tube will not pollute the sanitary ware, avoid the sanitary ware can not scrub the “red mark” and “blue mark”.
Because, at present, in the field of thin-wall stainless steel water supply pipes and fittings, the main difference between related similar products is the difference in connection mode, so the following introduces a most common and convenient thin-wall.
Connection mode of stainless steel water supply pipes and fittings – clamp type connection. A connection in which a pipe is connected with a socket fitting with a sealing ring and sealed and tightened by pressing the socket with a tool. The basic composition of the clamping pipe fitting is a special shaped pipe joint with an O sealing ring in a U-shaped groove at the end. When assembling. The stainless steel water pipe is inserted into the pipe fitting, and the pipe fitting and pipe of the sealing part are squeezed into a hexagonal shape with the sealing tool, so as to form sufficient connection strength, and the sealing effect is generated due to the compression deformation of the sealing ring. The cost of pipe fittings is low, suitable for the promotion of the civil market, the installation is simple, the construction speed is fast.
7. Cast iron pipe for water supply
Cast iron pipes for water supply have the advantages of strong corrosion resistance, convenient installation, long service life (under normal circumstances, the service life of underground cast iron pipes is more than 60 years) and low price. They are mostly used in water supply pipes with DN greater than or equal to 75 coffee, especially for buried laying. Its disadvantages are brittleness, large weight, small length and poor strength compared with steel pipe. There are three kinds of low pressure, common pressure and high pressure in the water supply cast iron pipes in our country.
In recent years, ductile iron pipe has been designed as the main riser in large high-rise buildings and used in indoor water supply system. Ductile iron pipe has thinner wall and higher strength than ordinary cast iron pipe, and its impact property is more than 10 times that of gray cast iron pipe. Ductile cast iron pipe with rubber ring mechanical connection or socket connection, can also be threaded flange connection.
Other pipes:
Hard polyvinyl chloride pipe (UPVC)
In the world, hard polyvinyl chloride pipe (UPVC) is a variety of plastic pipe consumption relatively large variety. Adopting this kind of pipe can positively alleviate the situation of steel shortage and energy shortage in our country, and economic benefits are.