Basic knowledge of pipe

1、 According to its manufacturing method, steel pipe can be divided into seamless steel pipe and welded steel pipe Seamless steel pipe is made of high quality carbon steel or alloy steel, including hot rolling and cold rolling (drawing) Welded steel pipe is made of rolled steel plate welded by butt joint or spiral joint In terms of manufacturing method, it is also divided into welded steel pipe for low-pressure fluid transmission, spiral welded steel pipe, direct rolled welded steel pipe, welded pipe, etc Seamless steel pipe can be used for all kinds of liquid and gas pipes Welded pipes can be used for water pipes, gas pipes, heating pipes, etc 1 Welded steel pipe 1.1 welded steel pipe and galvanized welded steel pipe for low pressure fluid transmission Welded steel pipe for low-pressure fluid transmission is made of carbon mild steel, which is the most commonly used small-diameter pipe in pipeline engineering It is suitable for conveying water, gas, steam and other media According to the different surface quality, it is divided into galvanized pipe (commonly known as white iron pipe) and non galvanized pipe (commonly known as black iron pipe) The inner and outer walls coated with a zinc protective layer are about 3% - 6% heavier than the non galvanized ones According to the different wall thickness of the pipe, it can be divided into thin-walled pipe, common pipe and thickened pipe The thin-walled tube is not suitable for conveying medium and can be used as casing 1.2 the straight seam rolled electric welded steel pipe and the straight seam rolled electric welded steel pipe can be divided into the electric welded steel pipe and the straight seam rolled welded steel pipe made of steel plate and welded on site It can be made into several pipe wall thicknesses 1.3 spiral seam welded steel pipe spiral seam welded steel pipe is divided into automatic submerged arc welded steel pipe and high frequency welded steel pipe A spiral seam automatic submerged arc welded steel pipe can be divided into class a pipe and class B pipe according to the pressure of transmission medium Class a pipe is generally made of ordinary carbon steel Q235, q235f and ordinary Low Alloy Structural Steel 16Mn by welding Class B pipe is made of Q235, q235f, Q195 and other steels by welding It is used as low pressure fluid conveying pipe Class B spiral seam high frequency welded steel pipe spiral seam high frequency welded steel pipe There is no uniform product standard, and it is generally made of ordinary carbon steel Q235, q235f and other steels 2 Seamless steel pipe seamless steel pipe is divided into hot rolled pipe and cold drawn (rolled) pipe according to the manufacturing method The maximum nominal diameter of cold drawn (rolled) pipe is 200mm, and the maximum nominal diameter of hot rolled pipe is 600 mm In pipeline engineering, when the pipe diameter is more than 57mm, hot-rolled pipe is often used, and when the pipe diameter is less than 57mm, cold drawn (rolled) pipe is often used There are three kinds of seamless steel pipes commonly used in pipeline engineering: 2.1 general seamless steel pipe The general seamless steel pipe is called seamless steel pipe for short It is made of ordinary carbon steel, high-quality carbon steel, ordinary low-alloy steel and alloy structural steel It is used to make liquid pipelines or structures and parts Seamless steel pipe is supplied according to outer diameter and wall thickness There are many kinds of wall thickness under the same outer diameter, and the pressure range is large Generally, the length of steel pipe is 3-12.5m for hot-rolled pipe and 1.5m-9m for cold drawn (rolled) pipe 2.2 seamless steel tubes for low and medium pressure boilers are made of No 10 and No 20 high-quality carbon steel with working temperature Cast iron pipe cast iron pipe is made of pig iron According to the different manufacturing methods, it can be divided into: Sand Mold Centrifugal socket straight pipe, continuous cast iron straight pipe and sand mold iron pipe According to the different materials used, it can be divided into: gray iron pipe, ductile iron pipe and high silicon iron pipe Cast iron pipes are mostly used in water supply, drainage and gas pipeline engineering 1 Water supply cast iron pipe 1.1 Sand mold centrifugal cast iron straight pipe The material of sand mold centrifugal cast iron straight pipe is gray cast iron, which is suitable for the transportation of water, gas and other pressure fluid 1.2 continuous cast iron straight pipe continuous cast iron straight pipe is a continuous cast gray cast iron pipe, which is suitable for the transportation of water, gas and other pressure fluid 2 Drainage cast iron pipe, common drainage cast iron socket pipe and pipe fittings Flexible anti-seismic interface drainage cast iron straight pipe, this kind of cast iron pipe is sealed by rubber ring and fastened by bolt, which has good flexibility and scalability under internal water pressure It can adapt to large axial displacement and lateral deflection, and it is suitable for indoor drainage pipe of high-rise building, especially for seismic area 3 Non ferrous metal pipe 1 Aluminum and aluminum alloy pipe aluminum and aluminum alloy refer to the industrial pure aluminum containing 98% aluminum and the aluminum alloy with copper, magnesium, manganese, zinc, chromium and other alloy elements as the main body Aluminum and aluminum alloy pipes are made of industrial pure aluminum or aluminum alloy by drawing or extrusion Aluminum has good acid corrosion resistance 2 Copper and copper alloy pipe copper pipe is mainly made of pure copper and phosphorus deoxidized copper, known as copper pipe or copper pipe brass pipe is made of common brass, lead brass and other brass 3 Lead and lead alloy pipe 4 Plastic pipe plastic pipe is generally made of plastic resin as raw material, adding stabilizer, lubricant, etc., and extruded in the pipe making machine by plastic method Because of its light weight, corrosion resistance, beautiful appearance, no bad smell, easy processing, and convenient construction, it has been widely used in construction engineering It is mainly used for water supply system piping, drainage, exhaust and sewage sanitary pipe, underground drainage pipe system, rainwater pipe and wire installation supporting conduit, etc There are two kinds of plastic pipes: thermoplastic pipe and thermosetting plastic pipe The main resins used for thermoplastic pipes are PVC, PE, PP, PS, ABS, Pb, etc.; the main resins used for thermosetting plastics are unsaturated polyester, epoxy, furan, phenolic, etc Table 1 lists the characteristics and main uses of these plastic pipes (see Table 1) Table 1 Comparison of the characteristics and main uses of several commonly used plastic pipes: name, characteristics, connection method, main use PVC pipe has better tensile and compressive strength, but its flexibility is not as good as other plastic pipes, with excellent corrosion resistance The price is the cheapest among all kinds of plastic pipes, but brittle bonding, socket rubber ring connection, flange thread connection at low temperature CPVC pipes used in residential, industrial and mining, agricultural water supply and drainage, irrigation, gas supply, exhaust pipe, wire conduit, rainwater pipe, industrial anti-corrosion pipe, etc have outstanding heat-resistant performance, with heat deformation temperature of 100 ℃, excellent chemical resistance performance, bonding, flange thread connection, hot water pipe PE pipe Light weight, good toughness, good low temperature resistance, non-toxic, low price, high impact strength, but low compressive and tensile strength Hot solution welding, flange thread connection, drinking water pipe, rainwater pipe, gas pipe, industrial corrosion-resistant pipe PP pipe It has good corrosion resistance, good strength, high surface hardness, surface finish, and certain high-temperature resistance It is used for hot-melt welding, flange thread connection, chemical sewage, sea water, oil and irrigation pipes, and it is used as heating pipe of indoor concrete floor heating system ABS pipe has good corrosion resistance, light weight, and higher heat resistance than PE and PVC, but it is more expensive Bonding, flange thread connection Pb pipes for sanitary ware, such as sewer, pipeline, sewage pipe, underground cable pipe, high anticorrosion industrial pipe, etc have strength between ground PE and PP, and flexibility between LDPE and HDPE Their outstanding characteristics are creep resistance (cold deformation), repeated winding, temperature resistance and good chemical performance Hot melt welding, flange thread connection Water supply pipes, hot and cold water pipes, gas pipes, underground high-rise pipes GRP pipes have excellent corrosion resistance, light weight, high strength and good design performance They are widely used in petrochemical pipes and large-diameter water supply and drainage pipes 1 Rigid PVC pipes and pipe fittings for building drainage UPVC pipes and pipe fittings for building drainage are made of PVL resin as the main raw material, adding special additives, and extruded and injection molded in the pipe making machine 1.1 characteristics (1) excellent physical performance UPVC pipes and pipe fittings are corrosion-resistant, high impact strength, low fluid resistance, non scaling, smooth inner wall, not easy to block, and meet the requirements of fire resistance of building materials, aging resistance, long service life The indoor and underground service life can be more than 50 years, and the outdoor service life can be up to 50 years (2) it is light in weight, convenient for transportation, storage and installation, and conducive to accelerating the project progress and reducing the construction cost (3) it can save construction cost, use UPVC pipes and fittings with lower cost than use the same specification of cast iron pipe system, and it is easy to maintain 1.2 application: it is suitable for the drainage system in buildings It can also be used for the industrial drainage system under the consideration of the heat resistance and conditions of the chemical resistance of the pipes It can be used continuously under the temperature of 60 ℃ and intermittently under the temperature of 80 ℃ 2 Unplasticized polyvinyl chloride plastic pipes and fittings for water supply The unplasticized polyvinyl chloride plastic pipes and fittings for water supply are made by mixing, plasticizing, extruding or injecting with the PVC resin of food hygiene grade as the main raw material, adding non-toxic special additives The product conforms to the national drinking water hygiene standard and adopts socket bonding, elastic sealing ring, metal transformer joint and other connection methods 2.1 features (1) excellent physical properties, UPVC water supply pipes and pipe fittings have high impact strength, smooth surface, small fluid resistance, water delivery capacity of 120% of the same type of steel pipes, and are not easy to scale, and long-term use water delivery capacity is not reduced (2) it shall be corrosion-resistant and rust free, and shall not be damaged due to the corrosiveness of soil and water and the effect of substances, with a general service life of more than 50 years (3) the thermal conductivity is small, so it is not easy to crack in winter (4) light weight, convenient for transportation, storage and installation, high labor efficiency, which is conducive to accelerating the project progress and reducing the construction cost 2.2 the utility model is mainly used for the indoor water supply system of the civil residence, which can replace the traditional white iron pipes and pipe fittings, and can be used for the drainage, sewage discharge, transmission of corrosive fluid and other systems It can also be used to transport water supply pipes of buildings (overhead or buried) with temperature below 45 ℃ 3 The composite foamed UPVC pipe is made of three layers of PVC formula Through the modified inner and outer layers of PVC and honeycomb structure core layer, the composite foamed UPVC pipe not only has the characteristics that the traditional PVC solid wall pipe is superior to the cast iron and copper pipe, but also has the characteristics that the traditional PVC solid wall pipe, cast iron pipe and steel pipe cannot match Composite foamed UPVC pipe is a new type of plastic pipe developed in China in recent years 3.1 features: light weight, low cost, low fluid resistance, acid and alkali resistance, long service life, high mechanical strength, good sound insulation, strong electrical insulation, simple construction, heat and cold resistance 3.2 application: it is suitable for low pressure water supply pipes, drainage pipes, sewage pipes, indoor air conditioning and ventilation pipes, exhaust pipes, wire and cable casings, cold and hot fluid transmission pipes, chemical and pharmaceutical industrial pipes in industrial and residential buildings 4 UPVC electrical pipes and joints are made of PVC resin and special additives by plasticizing and extruding 4.1 features: good fire resistance, corrosion resistance, climate resistance, light weight, beautiful appearance, low cost, product matching, convenient construction, etc 4.2 purpose: it is applicable to all kinds of buildings for indoor and outdoor (open laying, concealed laying) electric chlorine installation sleeve, playing the role of beautifying indoor environment, fire prevention, safety, insulation and wire decoration 5 Soft PVC plastic pipe is made of PVC resin with plasticizer