First, the classification of pipes
1. Classified by production method
(1) Seamless pipe - hot rolled pipe, cold rolled pipe, cold drawn pipe, extruded pipe, top pipe
(2) welded pipe
(a) by process - arc welded pipe, electric resistance welded pipe (high frequency, low frequency), gas welded pipe, furnace welded pipe
(b) According to the weld seam - straight seam welded pipe, spiral welded pipe
2, according to the shape of the section
(1) Simple section steel pipe - round steel pipe, square steel pipe, elliptical steel pipe, triangular steel pipe, hexagonal steel pipe, diamond steel pipe, octagonal steel pipe, semicircular steel circle, other
(2) Complex section steel pipe—unequal hexagonal steel pipe, five-petal plum-shaped steel pipe, double convex steel pipe, double concave steel pipe, melon-shaped steel pipe, conical steel pipe, corrugated steel pipe, case steel pipe, others
3, according to wall thickness classification - thin-walled steel pipe, thick-walled steel pipe
4. Classification by use - steel pipe for pipeline, steel pipe for thermal equipment, steel pipe for machinery industry, petroleum, geological drilling steel pipe, container steel pipe, chemical industry steel pipe, special purpose steel pipe, others
Second, seamless steel pipe
It is a long strip of steel with a hollow section and no seams around it. Steel pipes have a hollow section and are used in large quantities as pipes for transporting fluids, such as pipes for transporting oil, natural gas, gas, water and certain solid materials. Compared with solid steel such as round steel, the steel pipe is lighter in weight when it has the same bending and torsional strength. It is an economical section steel and is widely used in the manufacture of structural parts and mechanical parts, such as oil drill pipes, automobile transmission shafts, bicycles. Shelf and steel scaffolding used in construction. The use of steel pipes to manufacture ring-shaped parts can improve material utilization, simplify manufacturing processes, save materials and processing man-hours, such as rolling bearing rings, jacks, etc., and have been widely used in steel pipes. Steel pipes are also indispensable materials for various conventional weapons, and barrels, barrels, etc. are all made of steel pipes. Steel pipes can be divided into round pipes and shaped pipes according to the shape of the cross-sectional area. Since the area of ​​the circle is the largest under the condition of equal circumference, more fluid can be transported by the circular tube. In addition, the circular section is subjected to a relatively uniform force when subjected to internal or external radial pressure, and therefore, most of the steel pipes are round pipes.
However, the round pipe also has certain limitations. For example, under the condition of being bent by the plane, the round pipe is not as strong as the square and rectangular pipe, and some agricultural machinery skeletons, steel wood furniture, etc. are commonly used square and rectangular pipes. Shaped steel pipes of other cross-section shapes are also required depending on the application.
1. Structural seamless steel pipe (GB/T8162-1999) is a seamless steel pipe used for general structural and mechanical structures.
2. Seamless steel pipe for fluid transportation (GB/T8163-1999) is a general seamless steel pipe for conveying fluids such as water, oil and gas.
3. Seamless steel pipe for low and medium pressure boilers (GB3087-1999) is used for manufacturing superheated steam pipes, boiling water pipes and locomotive boiler superheated steam pipes, large smoke pipes, small smoke pipes and arch bricks. Hot-rolled and cold-drawn (rolled) seamless steel tubes of high-quality carbon structural steel for pipe use.
4. Seamless steel pipe for high-pressure boiler (GB5310-1995) is a high-quality carbon steel, alloy steel and stainless steel heat-resistant steel seamless pipe for the heating surface of water tube boilers for high pressure and above.
5. High-pressure seamless steel pipe for chemical fertilizer equipment (GB6479-86) is a high-quality carbon structural steel and alloy steel seamless steel pipe suitable for chemical equipment and pipelines with working temperature of -40~400 °C and working pressure of 10~30Ma.
6. Seamless steel pipe for petroleum cracking (GB9948-88) is a seamless pipe for furnace tubes, heat exchangers and pipes suitable for petroleum refineries.
7. Geological drilling steel pipe (YB235-70) is a steel pipe used for geological drilling by the geological department. It can be divided into drill pipe, drill collar, core pipe, casing and sedimentation pipe according to the application.
8. Seamless core steel pipe for diamond core drilling (GB3423-82) is a seamless steel pipe for drill pipe, core rod and casing used for diamond core drilling.
9. Oil Drilling Pipe (YB528-65) is a seamless steel pipe used for thickening or external thickening at both ends of oil drilling. There are two kinds of steel pipe and no wire, the wire pipe is connected by a joint, and the non-wire pipe is welded by a butt welding method and a tool joint.
10. Carbon steel seamless steel pipe for ships (GB5213-85) is a carbon steel seamless steel pipe for the manufacture of ship class I pressure pipe system, class II pressure pipe system, boiler and superheater. The working temperature of the carbon steel seamless steel pipe wall does not exceed 450 ° C, and the working temperature of the alloy steel seamless steel pipe wall exceeds 450 ° C.
11. Seamless steel pipe for automobile semi-axle casing (GB3088-82) is a high-quality carbon structural steel and alloy structural steel hot-rolled seamless steel pipe for the manufacture of automobile semi-axle casing and drive axle housing shaft tube.
12. High-pressure oil pipe for diesel engine (GB3093-86) is a cold drawn seamless steel pipe for the manufacture of high-pressure pipes for diesel injection systems.
13. Precision inner diameter seamless steel pipe for hydraulic and pneumatic cylinders (GB8713-88) is a cold drawn or cold rolled precision seamless steel pipe with precision inner diameter for the manufacture of hydraulic and pneumatic cylinders.
14. Cold drawn or cold rolled precision seamless steel pipe (GB3639-83) is a cold drawn or cold rolled precision seamless steel pipe with high dimensional accuracy and good surface finish for mechanical structures and hydraulic equipment.
The use of precision seamless steel tubes to manufacture mechanical structures or hydraulic equipment can greatly reduce machining time, improve material utilization, and improve product quality.
15. Structural stainless steel seamless steel pipe (GB/T14975-1994) is widely used in the chemical, petroleum, textile, medical, food, machinery and other industries of corrosion-resistant pipes and structural parts and parts of stainless steel hot rolling ( Squeeze, expand) and cold drawn (rolled) seamless steel tubes.
16. Stainless steel seamless pipe for fluid transportation (GB/T14976-1994) is a hot-rolled (extruded, expanded) and cold drawn (rolled) seamless steel pipe made of stainless steel for conveying fluid.
17. Shaped seamless steel pipe is a general term for seamless steel pipes of other cross-section shapes other than round pipes. According to the shape and size of the cross-section of the steel pipe, it can be divided into the same wall thickness profiled seamless steel pipe (code D), the unequal wall thickness profiled seamless steel pipe (code BD), and the variable diameter profiled seamless steel pipe (code BJ). Shaped seamless tubes are widely used in a variety of structural parts, tools and mechanical parts. Compared with the round pipe, the special-shaped pipe generally has a large moment of inertia and a section modulus, and has a large bending and torsion resistance, which can greatly reduce the structural weight and save steel.
Third, welded steel pipe
Welded steel pipe, also called welded pipe, is a steel pipe made by welding a steel plate or a steel strip after being crimped. The welded steel pipe has simple production process, high production efficiency, many varieties and specifications, and less equipment, but the general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of high-quality strip continuous rolling production and the advancement of welding and inspection technology, the quality of welded joints has been continuously improved, the variety specifications of welded steel pipes have been increasing, and more and more fields have replaced Seam steel pipe. Welded steel pipes are divided into straight welded pipes and spiral welded pipes in the form of welds.
Straight seam welded pipe has simple production process, high production efficiency, low cost and rapid development. The strength of the spiral welded pipe is generally higher than that of the straight welded pipe. It is possible to produce a welded pipe with a large diameter by using a narrow blank, and it is also possible to produce a welded pipe having a different pipe diameter by using a blank of the same width. However, compared with the straight pipe of the same length, the weld length is increased by 30 to 100%, and the production speed is low.
Therefore, most of the smaller diameter welded pipes are straight seam welded, and the large diameter welded pipes are mostly spiral welded.
1. Welded steel pipe for low-pressure fluid transportation (GB/T3092-1993) is also called general welded pipe, commonly known as black pipe. It is a welded steel pipe used for conveying general lower pressure fluids such as water, gas, air, oil and heating steam and other purposes. The thickness of the steel pipe is divided into ordinary steel pipe and thick steel pipe; the pipe end form is divided into non-threaded steel pipe (light pipe) and threaded steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), and the nominal diameter is an approximate value of the inner diameter. It is customary to use inches, such as 11/2. The welded steel pipe for low-pressure fluid transportation is mainly used as a raw pipe for galvanized welded steel pipe for low-pressure fluid transportation, in addition to being directly used for conveying fluid.
2. Galvanized welded steel pipe for low pressure fluid transportation (GB/T3091-1993) is also called galvanized electric welded steel pipe, commonly known as white tube. It is a hot dip galvanizing (furnace welding or electric welding) steel pipe for transporting water, gas, air oil, heating steam, warm water and other general lower pressure fluids or other purposes. The thickness of the steel pipe is divided into ordinary galvanized steel pipe and thick galvanized steel pipe; the connection end form is divided into non-thread galvanized steel pipe and threaded galvanized steel pipe. The specification of the steel pipe is expressed by the nominal diameter (mm), and the nominal diameter is an approximate value of the inner diameter. It is customary to use inches, such as 11/2.
3. Ordinary carbon steel wire casing (GB3640-88) is a steel pipe used to protect electric wires in electrical installation projects such as industrial and civil construction, installation machinery and equipment.
4. Straight seam electric welded steel pipe (YB242-63) is a steel pipe whose weld is parallel to the longitudinal direction of the steel pipe. Usually divided into metric electric welded steel pipe, welded thin-walled pipe, transformer cooling oil pipe and so on.
5. Spiral-slot submerged arc welded steel pipe (SY5036-83) for pressure-bearing fluid transportation is a hot-rolled steel strip coil for tube blank, which is often spiral-formed and welded by double-sided submerged arc welding for pressure fluid transportation. Spiral seam steel pipe. The steel pipe has strong pressure bearing capacity and good welding performance. It is safe and reliable after various strict scientific tests and tests. The steel pipe has a large caliber, high conveying efficiency, and can save investment in laying pipelines. It is mainly used to transport oil and natural gas pipelines.
6. Spiral seam high-frequency welded steel pipe (SY5038-83) for pressure fluid conveying is a hot-rolled steel strip coil for tube blank, which is often spiral-formed by high-frequency lap welding for pressure fluid transport. Spiral seam high frequency welded steel pipe. The steel pipe has strong pressure bearing capacity and good plasticity, which is convenient for welding and processing. After various strict and scientific inspections and tests, the use is safe and reliable, the steel pipe has large caliber, high conveying efficiency, and can save investment in laying pipelines. It is mainly used for laying pipelines for transporting oil and natural gas.
7. General spiral spiral submerged arc welded steel pipe (SY5037-83) for low-pressure fluid transportation is made of hot-rolled steel strip coil for tube blank, regular temperature spiral forming, double-sided automatic submerged arc welding or single-sided welding method. Submerged arc welded steel pipes for general low-pressure fluid transportation such as water, gas, air and steam.
8. General high-pressure fluid conveying spiral spiral high-frequency welded steel pipe (SY5039-83) is a hot-rolled steel strip coil for tube blank, regular temperature spiral forming, high-frequency lap welding welding for general low-pressure fluid conveying spiral High-frequency welded steel pipe.
9. Spiral welded steel pipe (SY5040-83) for piles is made of hot-rolled steel strip coils, which are often spiral-formed by double-sided submerged arc welding or high-frequency welding for civil engineering structures and wharfs. Steel pipes for foundation piles such as bridges.
Fourth, steel-plastic composite pipe, large diameter coated steel pipe
The steel-plastic composite pipe is made of hot-dip galvanized steel pipe as a base material, and is coated with plastic on the inner wall (if necessary, the outer wall is required) by powder melt-spraying technology, and the performance is excellent. Compared with galvanized pipe, it has the advantages of corrosion resistance, no rust, no fouling, smooth and smooth, clean and non-toxic, and long service life. According to tests, the service life of steel-plastic composite pipes is more than three times that of galvanized pipes. Compared with plastic tubes, it has the advantages of high mechanical strength, good pressure resistance and heat resistance. Since the substrate is a steel pipe, there is no problem of embrittlement or aging. It can be widely used in fluid transportation and heating projects such as tap water, gas, chemical products, etc. It is an upgraded product of galvanized pipe. Because the installation method is basically the same as that of the traditional galvanized pipe, the pipe form is also the same, and it can replace the aluminum-plastic composite pipe to play a role in the large-diameter tap water transportation. It has been welcomed by users and has become the most competitive in the pipeline market. One of the new products.
The coated steel pipe is made of plastic coated on the basis of large diameter spiral welded pipe and high frequency welded pipe. The maximum pipe diameter is up to 1200mm. It can be coated with polyvinyl chloride (PVC), polyethylene (PE) and epoxy according to different needs. Resin (EPOZY) and other plastic coatings with different properties, good adhesion, strong corrosion resistance, strong acid, alkali and other chemical corrosion resistance, non-toxic, non-corrosive, wear-resistant, impact-resistant, high-permeability The surface of the pipe is smooth and does not adhere to any substance, which can reduce the resistance during transportation, increase the flow rate and transportation efficiency, and reduce the transmission pressure loss. The coating has no solvent and no exudable substances, so it will not pollute the medium to be transported, thus ensuring the purity and hygienicity of the fluid. It can be used alternately between -40 ° C and +80 ° C in the range of hot and cold cycles, without aging, It does not crack and can be used in harsh environments such as cold areas.
Large diameter coated steel pipes are widely used in tap water, natural gas, petroleum, chemical, pharmaceutical, telecommunications, electric power, marine and other engineering fields.
Use of the classification of pipes
First, steel pipe
Steel pipes are classified into two types: seamless steel pipes and welded steel pipes according to their manufacturing methods. The seamless steel pipe is made of high-quality carbon steel or alloy steel and has hot rolling and cold rolling (extraction). The welded steel pipe is formed by welding a steel plate rolled into a tubular shape by a seam or a spiral seam. In terms of the manufacturing method, it is further divided into a welded steel pipe for low-pressure fluid transportation, a spiral-welded electric steel pipe, a direct-wound welded steel pipe, an electric welded pipe, and the like. Seamless steel tubes can be used in a variety of liquids, gas pipelines, and the like. 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 transportation
The welded steel pipe for low-pressure fluid transportation is made of carbon soft steel. It is the most commonly used small-diameter pipe in pipeline engineering. It is suitable for conveying water, gas, steam and other media. It is divided into plated according to its surface quality. Zinc pipes (commonly known as white iron pipes) and non-galvanized pipes (commonly known as black iron pipes). The inner and outer walls are coated with a zinc protective layer about 3% to 6% less than the non-galvanized. According to the different wall thickness of the pipe, it is divided into three types: thin-walled pipe, ordinary pipe and thickened pipe. Thin-walled tubes are not suitable for conveying media and can be used as casings.
1.2 Straight seam rolled electric welded steel pipe
Straight seam rolled electric welded steel pipe can be divided into electric welded steel pipe and straight seam welded steel pipe which is rolled and rolled by field steel plate. Can make several wall thicknesses.
1.3 spiral seam welded steel pipe
Spiral seam welded steel pipes are divided into automatic submerged arc welded steel pipes and high frequency welded steel pipes.
a. Spiral seam automatic submerged arc welded steel pipe is divided into Class A pipe and Class B pipe according to the pressure of the conveying medium. Class A pipes are generally welded with ordinary carbon steel Q235, Q235F and ordinary low-alloy structural steel 16Mn. Class B pipes are welded with Q235, Q235F, Q195 and other steel materials and used as low-pressure fluid conveying pipes.
b. Spiral seam high-frequency welded steel pipe spiral seam high-frequency welded steel pipe, there is no uniform product standard, generally made of ordinary carbon steel Q235, Q235F and other steel.
2, seamless steel pipe
The seamless steel tubes are divided into hot rolled tubes and cold drawn (rolled) tubes according to the manufacturing method. The cold-rolled (rolled) pipe has a maximum nominal diameter of 200 mm and the hot-rolled pipe has a maximum nominal diameter of 600 mm. In pipeline engineering, hot-rolled pipes are often used when the pipe diameter exceeds 57 mm, and cold-drawn (rolled) pipes are often used when the pipe diameter is less than 57 mm. There are three types of seamless steel pipes commonly used in pipeline engineering:
2.1 General seamless steel pipe
General seamless steel pipe is referred to as seamless steel pipe. 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 to make structures and parts.
Seamless steel pipes are available in outer diameter and wall thickness, with a variety of wall thicknesses at the same outer diameter and a wide range of pressures. Usually the length of the steel pipe is 3-12.5 m for hot rolled pipes and 1.5-9 m for cold drawn (rolled) pipes.
2.2 Seamless steel pipe for low and medium pressure boilers
The seamless steel pipe for low and medium pressure boilers is made of high quality carbon steel No. 10 and No. 20, working temperature
The value of man is determined at the moment of temptation.
Second, cast iron pipe
The cast iron pipe is made of pig iron. According to the different manufacturing methods, it can be divided into: sand type centrifugal socket straight pipe, continuous cast iron straight pipe and sand type iron pipe. According to the materials used, it can be divided into: gray iron pipe, ductile iron pipe and high silicon iron pipe. Cast iron pipes are mostly used for pipeline projects such as water supply, drainage and gas.
1, water supply cast iron pipe
1.1 Sand type centrifugal cast iron straight pipe
The material of the sand type centrifugal cast iron straight pipe is gray cast iron, which is suitable for the transportation of pressure fluid such as water and gas.
1.2 continuous cast iron straight pipe
The continuous cast iron straight pipe is a continuously cast gray cast iron pipe, which is suitable for the transportation of pressure fluid such as water and gas.
2, drainage cast iron pipe
Ordinary drainage cast iron sockets and fittings. The flexible anti-vibration interface drains the cast iron straight pipe. The cast iron pipe is sealed by rubber ring and bolted, and has good flexibility and flexibility under internal water pressure. It can adapt to large axial displacement and lateral deflection, and is suitable for indoor drainage pipes of high-rise buildings, especially suitable for seismic zones.
Third, non-ferrous metal pipe
1. Aluminum and aluminum alloy tubes Aluminum and aluminum alloys refer to industrial pure aluminum containing 98% aluminum and aluminum alloys with aluminum as the main body and copper, magnesium, manganese, zinc, chromium and other alloying elements. Aluminum and aluminum alloy tubes are formed by drawing or extruding industrial pure aluminum or aluminum alloy. Aluminum has good acid corrosion resistance.
2. Copper and copper alloy tubes Copper tubes are mainly made of pure copper and phosphorus deoxidized copper, called copper tubes or copper tubes. Brass tubes are made of brass such as ordinary brass and lead brass.
3. Lead and lead alloy tubes
Fourth, plastic tube
The plastic pipe is generally made of plastic resin as a raw material, adding a stabilizer, a lubricant, etc., and is formed by extrusion in a pipe making machine by a 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 as piping, drainage, exhaust and sewage sanitary pipes, underground drainage pipe systems, rainwater pipes, and threading pipes for wire installation and the like for building water supply systems.
Plastic pipes are available in two categories: thermoplastic pipes and thermoset plastic pipes. The main resins used in thermoplastic pipes are polyvinyl chloride (PVC), polyethylene (PE), polypropylene (PP), polystyrene (PS), and propylene-Jing-butadiene-styrene ( ABS), polybutylene resin (PB), etc.; the main resins used in thermosetting plastics are unsaturated polyester resin, epoxy resin, fu resin, phenolic resin, and the like. 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 feature main purpose of connection
PVC pipe has good tensile and compressive strength, but its flexibility is not as good as other plastic pipes. It has excellent corrosion resistance and the price is the cheapest among all kinds of plastic pipes, but it is brittle and bonded at low temperature. Flange thread connection for residential life, industrial and mining, agricultural water supply and drainage, irrigation, gas supply, exhaust pipe, wire conduit, rainwater pipe, industrial anti-corrosion pipe, etc.
CPVC pipe has outstanding heat resistance, heat distortion temperature is 100 °C, excellent chemical resistance, flanged threaded hot water pipe
PE pipe is light in weight, good in toughness, good in low temperature resistance, non-toxic, cheaper in price, high in impact strength, but low in compression and tensile strength, hot melt welding, flange threaded drinking water pipe, rainwater pipe, gas pipeline Industrial corrosion resistant pipe
PP pipe has good corrosion resistance, good strength, high surface hardness, surface finish, high temperature resistance, hot melt welding, flange threaded chemical sewage, seawater, oil and irrigation pipes, used indoors. Concrete floor heating system heating pipe
ABS pipe has excellent corrosion resistance, light weight and heat resistance higher than PE and PVC, but it is more expensive. Bonding and flange thread connection for sanitary ware, sewage pipe, sewage pipe, sewage pipe, underground cable pipe, high anti-corrosion industrial pipe, etc.
PB pipe strength between the PE and PP, between the LDPE and HDPE flexibility, its outstanding features are creep resistance (cold deformation), repeated winding and continuous, temperature resistance, chemical properties are also very hot melt welding , flange threaded water supply pipe, hot and cold water pipe, gas pipe, underground high pipe
GRP pipe has excellent corrosion resistance, light weight, high strength, good design performance, socket rubber ring connection, flange connection, petrochemical pipeline and large diameter water supply and drainage pipe
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