According to different production methods, it can be divided into hot-rolled tubes, cold-rolled tubes, cold-drawn tubes, extruded tubes, etc.
1.1. Hot-rolled seamless steel pipes are generally produced on automatic pipe rolling units. After checking and removing surface defects, the solid tube blank is cut into the required length, centered on the perforated end face of the tube blank, then sent to the heating furnace for heating, and pierced on the piercing machine. Spin and advance the solid blank inside the process of piercing holes under the influence of the roller as well as the end. Then the solid blank is hollow, which is called gross pipe. Send to the automatic pipe rolling machine to continue rolling. Finally, the wall thickness is adjusted by the equalizing machine, and the size is sized by the sizing machine to meet the specification requirements. It is a relatively advanced method to produce hot-rolled A106b seamless steel pipes by using continuous rolling mills.
1.2. If you want to obtain seamless steel pipes with smaller size and better quality, you must use cold rolling, cold drawing, or a combination of the two. Cold rolling is usually carried out on a two-roll mill, and the steel pipe is rolled in an annular pass formed by a circular hole groove with variable cross-section and a stationary tapered plug. Cold drawing is usually carried out on a 0.5-100T single-chain or double-chain cold drawing machine.
1.3. Extrusion method The heated tube is placed in a closed extrusion cylinder, and the perforated rod and the extrusion rod move together to make the extruded part extrude from the smaller die hole. This method can produce steel pipes with smaller diameters.
2. Purpose
2.1. Seamless steel pipes are widely used. General-purpose seamless steel tubes are rolled from ordinary carbon structural steels, low alloy structural steels, or alloy structural steels with the highest output, and are mainly used as pipes or structural parts for conveying fluids.
2.2. There are three types of supplies according to different uses: a. Supply according to chemical composition and mechanical properties; b. Supply according to mechanical properties; c. Supply according to hydraulic test. Steel pipes supplied by Types A and B, if used to withstand liquid pressure, are also subject to hydrostatic testing.
2.3. There are many kinds of seamless steel pipes for special purposes, such as seamless steel pipes for boilers, seamless steel pipes for geological use, and seamless steel pipes for petroleum.
3. Type
3.1, A106b seamless steel pipes can be divided into hot-rolled pipes, cold-rolled pipes, cold-drawn pipes, extruded pipes, etc. according to different production methods.
3.2. According to the shape classification, there are round tubes and special-shaped tubes. In addition to square tubes and rectangular tubes, special-shaped tubes also include oval tubes, semicircular tubes, triangular tubes, hexagonal tubes, convex-shaped tubes, and plum-shaped tubes.
3.3. Different materials, it can be divided into ordinary carbon structural tubes, low alloy structural tubes, high-quality carbon structural tubes, alloy structural tubes, stainless steel tubes, etc.
3.4. According to special purposes, there are boiler tubes, geological tubes, oil tubes, etc.
4. Specifications and appearance quality
Seamless steel pipe according to GB/T8162-87
4.1. Specifications: The outer diameter of the hot-rolled tube is 32-630mm. Wall thickness 2.5 ~ 75mm. Cold-rolled (cold-drawn) tube outer diameter 5 ~ 200mm. Wall thickness 2.5 ~ 12mm.
4.2. Appearance quality: There must be no cracks, folds, rolling folds, delamination, hairlines, or scarring defects on the inner and outer surfaces of steel pipes. These defects should be completely removed, and the wall thickness and outer diameter must not exceed the negative deviation after removal.
4.3. Both ends of the steel pipe should be cut at right angles, and the burrs should be removed. Steel pipes with a wall thickness greater than 20mm are allowed to be cut by gas cutting and hot sawing. It is not necessary to cut the head after the agreement between the supply and demand parties.
4.4. Refer to GB3639-83 for “surface quality” of cold-drawn or cold-rolled precision A106b seamless steel pipes.
5. Chemical composition test
5.1. The chemical composition of domestic seamless steel pipes supplied according to chemical composition and mechanical properties, such as steel No. 10, 15, 20, 25, 30, 35, 40, 45, and 50, shall comply with the provisions of GB/T699-88. Imported seamless steel pipes shall be inspected according to the relevant standards stipulated in the contract. The chemical composition of 09MnV, 16Mn, and 15MnV steel shall comply with the provisions of GB1591-79.
5.2. Refer to the relevant parts of GB223-84 “Chemical Analysis Methods of Steel and Alloy” for specific analysis methods.
5.3. For analysis deviation, refer to GB222-84 “Permissible Deviation of Chemical Composition of Samples and Finished Products for Steel Chemical Analysis”.
6. Physical performance test
6.1. Domestic seamless steel pipes and ordinary carbon steels are manufactured according to GB/T700-88 Class A steel (but must ensure that the sulfur content does not exceed 0.050% and the phosphorus content does not exceed 0.045%). The performance should meet the values stipulated in the GB8162-87 table.
6.2. The domestic seamless steel pipes supplied according to the hydrostatic test must ensure the hydrostatic test specified in the standard.
6.3. The physical performance inspection of imported seamless steel pipes shall be carried out by the relevant standards stipulated in the contract.
7. Main import and export situation
7.1. Generally, the import volume of seamless steel pipes is very large. The main importing countries are Germany and Japan. European countries such as Romania, Russia, Switzerland, France, Spain, Czech Republic, Yugoslavia, Hungary and other countries have imports. There is also a small amount imported from Argentina, Mexico, and other countries in South America.
7.2. According to the different requirements of my country’s consumer units, there are more than 100 specifications of imported seamless steel pipes, and the common specifications are 15922mm, 1595mm, and 15918mm. 114.38mm, 114.310mm, 114.313mm. The length is generally 5-8m or 4-7m. It is mainly a hot-rolled carbon structure, and the steel grades are ST35, ST45 and ST65. The smallest diameter of imported specifications is 305mm, and the largest is 47813mm.
7.3. A small number of seamless steel pipes with small diameters and thin walls have been imported from France and Spain, such as 183mm, 223mm, 26.93mm, etc. The general rules of the Mannesmann Tube Works in Germany apply.
7.4. For seamless steel pipes imported from Hungary and Japan, DIN2448 and DIN1629 are often referred to.
7.5. In the case of import claims, the quality problems of imported seamless steel pipes mainly include unqualified chemical composition, splitting in flattening test, low tensile strength, serious corrosion, pits, etc.
8. Packaging
According to the provisions of GB2102-88. There are three types of steel pipe packaging: bundling, boxing, oiled bundling, or oiled boxing.
Welded steel pipe, also known as welded pipe, is a steel pipe made of steel plate or steel strip after crimping and welding. Welded steel pipe has a simple production process, high production efficiency, many varieties and specifications, and less equipment investment, but its general strength is lower than that of seamless steel pipe. Since the 1930s, with the rapid development of continuous rolling production of high-quality strip steel and the advancement of welding and inspection technology, the quality of welds has been continuously improved, and the varieties and specifications of welded steel pipes have increased day by day and replaced seamless steel pipes in more and more fields. Seam steel pipe. Welded steel pipes are divided into straight seam welded pipes and spiral welded pipes according to the form of the weld seam.
The production process of straight seam welded pipe is simple, the production efficiency is high, the cost is low, and the development is rapid. The strength of the spiral welded pipe is generally higher than that of the straight seam welded pipe, and the welded pipe with a larger diameter can be produced with a narrower billet, and welded pipes with different diameters can be produced with the same width billet. But compared with the straight seam pipe of the same length, the weld length is increased by 30~100%, and the production speed is lower.
Therefore, most of the welded pipes with smaller diameters adopt straight seam welding, and most of the large diameter welded pipes adopt spiral welding.
① Welded steel pipes for low-pressure fluid transportation (GB/T3092-1993) are also called generally welded pipes, commonly known as clarinet pipes. It is a welded steel pipe used for conveying water, gas, air, oil, heating steam, and other general lower-pressure fluids and other purposes. The wall thickness of the steel pipe is divided into ordinary steel pipe and thickened steel pipe; the form of the pipe end is divided into unthreaded 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 express in inches, such as 11/2 and so on. In addition to being directly used to transport fluids, welded steel pipes for low-pressure fluid transportation are also widely used as raw pipes for galvanized welded steel pipes for low-pressure fluid transportation.
②Galvanized welded steel pipe for low-pressure fluid transportation (GB/T3091-1993) is also called galvanized electric welded steel pipe, commonly known as white pipe. It is a hot-dip galvanized welded (furnace welded or electrically welded) steel pipe used for conveying water, gas, air oil, heating steam, warm water, and other general lower-pressure fluids or other purposes. The wall thickness of the steel pipe is divided into ordinary galvanized steel pipe and thickened galvanized steel pipe; the form of the pipe end is divided into non-threaded 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 express in inches, such as 11/2 and so on.
③ Ordinary carbon steel wire casing (GB3640-88) is a steel pipe used to protect wires in electrical installation projects such as industrial and civil buildings, and installation of machinery and equipment.
④ Straight seam electric welded steel pipe (YB242-63) is a steel pipe whose weld seam is parallel to the longitudinal direction of the steel pipe. It is usually divided into metric electric welded steel pipe, electric welded thin-walled pipe, transformer cooling oil pipe, and so on.
⑤ Spiral submerged arc welded steel pipe for pressure fluid transportation (SY5036-83) is made of hot-rolled steel strip coils, spirally formed at normal temperature, welded by double-sided submerged arc welding, and used for pressure fluid transportation. Seam steel pipe. The steel pipe has strong pressure-bearing capacity and good welding performance. After various strict scientific inspections and tests, it is safe and reliable to use. The diameter of the steel pipe is large, the transmission efficiency is high, and the investment in laying pipelines can be saved. It is mainly used for pipelines transporting oil and natural gas.
⑥ Spiral seam high-frequency welded steel pipe for pressure fluid transportation (SY5038-83) is made of hot-rolled steel strip coils, spirally formed at normal temperature, welded by high-frequency lap welding, and used for pressure fluid transportation Spiral seam high-frequency welded steel pipe. The steel pipe has strong pressure bearing capacity, good plasticity, and is convenient for welding and processing; after various strict and scientific inspections and tests, it is safe and reliable to use, the diameter of the steel pipe is large, the transmission efficiency is high, and the investment in laying pipelines can be saved. It is mainly used for laying pipelines for transporting oil and natural gas.
The spiral seam submerged arc welded steel pipe for general low-pressure fluid transportation (SY5037-83) is made of hot-rolled steel strip as the tube blank, spirally formed at a constant temperature, and is made by double-sided automatic submerged arc welding or single-sided welding. Submerged arc welded steel pipes for general low-pressure fluid transportation such as gas, air, and steam.
⑧Spiral seam high-frequency welded steel pipe for general low-pressure fluid transportation (SY5039-83) is made of hot-rolled steel strip coils, spirally formed at a constant temperature, and welded by high-frequency lap welding method for spiral seam for general low-pressure fluid transportation High frequency welded steel pipe.
⑨ Spiral welded steel pipe for piles (SY5040-83) is made of hot-rolled steel strip coils, spirally formed at normal temperature, and made by double-sided submerged arc welding or high-frequency welding. It is used for civil engineering structures, wharves, and Steel pipes for foundation piles such as bridges.
Steel-plastic composite pipe, large-diameter coated steel pipe
The steel-plastic composite pipe is made of hot-dip galvanized steel pipe as the substrate, and the inner wall (or outer wall if necessary) is coated with plastic by powder fusion spraying technology, with excellent performance. Compared with galvanized pipe, it has the advantages of anti-corrosion, no rust, no fouling, smooth and smooth, clean and non-toxic, and long service life. According to tests, the service life of the steel-plastic composite pipe is more than three times that of the galvanized pipe. Compared with plastic pipes, 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, and chemical products. It is an upgraded product of galvanized pipes. Because its installation method is the same as that of the traditional galvanized pipe, and the form of the pipe fittings is also the same, and it can replace the aluminum-plastic composite pipe to play a role in large-diameter tap water transportation. It is very popular among users and has become the most competitive pipe in the pipeline market. One of the new products.
Coated steel pipes are formed by coating plastic based on large-diameter spiral welded pipes and high-frequency welded pipes. 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-rusting, wear-resistant, impact resistance, strong penetration resistance, The surface of the pipeline is smooth and does not adhere to any substance, which can reduce the resistance during transportation, improve the flow rate and transportation efficiency, and reduce the pressure loss of transportation. There is no solvent and no exudate substances in the coating, so it will not pollute the conveyed medium, thus ensuring the purity and hygiene of the fluid. It can be used alternately in cold and hot cycles in the range of -40°C to +80°C, without aging, It does not crack, so it can be used in harsh environments such as cold regions.
Post time: Aug-29-2023