The development of foreign steel pipe production technology and Its Enlightenment to us
General situation of development
In the past 10 years, steel pipe production technology has developed rapidly, especially seamless steel pipe production technology. In order to improve product size accuracy, expand variety, improve product internal quality, reduce energy consumption and cost, many new processes and equipment have been developed and applied in production.
① Seamless steel pipe is produced directly from continuous casting round (square) billet.
Nearly 100% of the main seamless steel pipe manufacturers in Germany, Japan, the United States and France take continuous casting billet as raw material. According to the data from 1983 to 1984, Sumitomo of Japan can reduce the cost of steel pipe by 4000 yen per ton by using continuous casting slab as raw material, while cisu thinks that the cost can be reduced by 50-60 US dollars per ton and the scrap rate can be reduced by 2 / 3.
② The technology of equalizing the wall of capillary after perforation.
After the ppm (push mill and piercer), the two spoke cross rolling extension machine is used, and after the cross rolling piercer, the three series extension machine is used. The former can correct 70% of the deviation of capillary wall thickness, while the latter can correct 50%. Because of the uniform wall technology adopted in the production, the wall thickness deviation of the finished steel pipe can be less than ± 5%.
③ Capillary sizing (reducing) process.
The diameter difference between the front end and the back end of the pierced long wool pipe can be eliminated by sizing it, so as to improve the operation of the pipe rolling mill. It can be used to produce two or three kinds of diameter pipes with one kind of diameter pipe blank, which can reduce the blank specification and is beneficial to the production of continuous casting billet.
④ Direct heat treatment.
N80 and P110 Oil well pipes have been successfully produced by on-line direct quenching after the sizing of seamless steel pipes. Compared with the general heat treatment method, the cost can be reduced by about 25%. This technology is used in the Φ 400mm automatic pipe rolling plant of Kawasaki and the Φ 244.5mm continuous pipe rolling plant of Jingmin steel pipe plant of Japan.
⑤ The STEL form process of producing large diameter spiral welded pipe with wide plate as raw material.
First, the wide plate shall be subject to NDT outside the forming line and the four sides shall be processed to ensure that both sides of the steel plate are vertical to both ends and there is no sickle bend, and the groove shall be planed. Several steel plates are butt welded with strip steel of about 40-50m long, and then the long strip steel is moved to the forming line and welded with the previous strip steel to ensure continuous production. The forming machine is equipped with an automatic control device for spiral weld clearance to ensure the weld quality. By controlling rolling and heat treatment, the steel plate can obtain high strength and low temperature toughness, thus improving the mechanical properties of welded pipe.
⑥ Cold expanding process of large diameter straight welded pipe.
In order to eliminate the residual stress in the forming process of large-diameter straight welded pipe and improve the size accuracy of steel pipe, the cold expanding process is adopted in the production of large-diameter welded pipe, which can enlarge the diameter of steel pipe by 1% and improve the mechanical properties. The hydraulic expanding machine used in the past has been replaced by the mechanical expanding machine with convenient operation.
⑦ Remove the burr in the welding pipe.
It is required to remove the inner burr of the weld in the American Standard; it is also stipulated in the original soviet standard that the user has the right to require the electric welding pipe with a diameter of 33mm to remove or flatten the inner burr. Because the removal of internal burr can improve the use efficiency of steel pipe.
⑧ Automatic testing and nondestructive testing technology.
In the production of steel pipe, the on-line inspection and NDT have reached the stage of complete application. The modern continuous rolling workshop is controlled by computer, and calculated according to the detected data of diameter, length, thickness, temperature and tools of the rolling piece. Then, each rolling mill is reset and adjusted dynamically. AGC is used in the rolling mill.
The nondestructive testing equipment for steel pipe has been composed of a high-precision and high-efficiency testing system by a variety of testing technologies. The high-precision system is composed of ultrasonic, compound magnetic field, inner surface eddy current and pipe end electromagnetic technology. The high efficiency system consists of three technologies: composite magnetic field, ultrasonic flaw detection and ultrasonic thickness measurement.
⑨ Automatic detection technology of oil well pipe thread.
In the Φ 244.5mm continuous pipe rolling workshop of Jingmin plant of Japan steel pipe company, the oil well pipe processing line is directly connected with the hot rolling production line, and automatic control is implemented. The oil well pipe thread shall be inspected jointly by optical black skin tester and thread size inspection machine.
⑩ DOM steel pipe production process.
DOM steel pipe is a kind of cold drawn electric welding steel pipe used as raw material of mechanical parts. Because the deviation of the wall thickness of the welded steel pipe is very small, the mechanical cutting can be reduced and the concentricity can be increased after cold drawing. The maximum diameter of DOM steel pipe in the United States has reached Φ 406 mm, the maximum length is 18.3 m, the maximum weight is 2318 kg, and the maximum pulling force of the puller has reached 4.55 Mn.
① Push piercer (PPM).
In 1977, ppm was first applied in the Φ 400mm automatic pipe rolling workshop of Bafan plant of Nippon Steel in Japan; in 1978, it was applied in the continuous pipe rolling workshop of dalmin company in Italy. After that, ppm was also applied in the United States, the Soviet Union and other countries. This piercer is used to pierce square billets into hollow round billets. It can pierce all kinds of carbon steel, low alloy steel, 13% Cr steel and 9% CrMo steel. The wall thickness deviation of hollow billet can be less than ± 15%, the average is ± 8%, and the wall thickness deviation of finished steel pipe can be less than ± 5%. The ratio of hollow billet length to inner diameter can reach 35-40. The output per hour is 100-180 pieces, and the maximum weight of the billet has reached 4.8t.
② Cone type cross rolling piercer.
This kind of piercer has been put into production in the Soviet Union, Germany, Japan and South Africa, and China is also building this kind of equipment. This kind of piercer has cone-shaped spokes. In addition to feeding angle, it also has toe angle. The rolling angles of the piercer which has been put into production are 10 °, 15 °, 17 ° and 27.6 °. Due to the rolling angle, the mannesman effect is limited during piercing, and the strain caused by the circumferential shear strain and surface distortion of the metal can be minimized, so that all kinds of steel can be pierced and have good internal and external surface quality. The elongation coefficient of the piercer can reach 6, the expanding capacity can reach 40%, and the D / s value of the capillary can reach 30. If the large guide plate is used as the guide, the perforation efficiency can reach 110% and the perforation speed can reach 1.5m/s.
It is a new type of continuous rolling mill developed in the 1970s and built 9 sets in the 1980s. The movement of mandrel is limited to move forward at a constant speed during pipe rolling, which avoids the “bulging” defect of steel pipe during full floating mandrel continuous rolling. It can produce medium and large diameter seamless steel pipe with wall thickness deviation less than ± 8%. In 1989, the largest MPM mill was built in the Soviet Union, with a maximum diameter of 425.4mm. Japan, France and semi floating mandrel mill are put into production. When the stop mandrel is close to the end of rolling, the mandrel is separated from the stop device and rolled out together with the steel pipe, which can improve the productivity. This operation method is suitable for small size continuous rolling mill.
④ Walking beam furnace.
The heating quality of the walking beam furnace is better than that of the ring furnace. It has been applied to the production of seamless steel pipe under the condition that the material and the mechanical beat can be solved. The step furnace has uniform heating, which is beneficial to improve the wall thickness nonuniformity F and is easier to operate than the ring furnace. This kind of furnace has been used in several newly built steel pipe workshops in the United States, Japan, the Soviet Union and other countries.
⑤ Welding pipe row spokes type machine.
It has the advantages of flat edge of strip steel, reliable butt joint due to element deformation, high welding quality assurance, large universality of preformed series, no need to replace the platoon series due to the change of product specifications, high operation rate, etc. it is suitable for large and medium caliber electric welding pipe workshop. This technology has been used in some small workshops.
⑥ Automatic control of welding temperature and extrusion pressure of welded pipe.
Automatic temperature control is to adjust the output power of the welding machine according to the detected weld temperature. The combination of temperature control and extrusion pressure control makes the weld quality and the deviation of outer diameter of steel pipe reach the best effect.
⑦ Spiral looper with steel strip.
There are many types of looper, but only the spiral looper is better. It has compact structure, large storage capacity, reliable operation and no scratch on the strip steel, so it has been popularized. Small and medium size pipe welding machine can be vertical, large size pipe welding machine can be horizontal.
⑧ On line fast steel pipe cutting equipment.
It is a control system that combines the control system of the calculation bar and DC motor with the corresponding hydraulic and pneumatic servo systems, which can make the cut-off deviation less than ± 8mm. It can cut the sample, cut the butt welding area of the strip steel, dynamically adjust the cutting length of the steel pipe and achieve the best cutting length.
⑨ UOE large diameter straight welded pipe equipment.
In the 1970s, 9 sets were built abroad, with the maximum press capacity of 600mn, the maximum steel pipe diameter of 1628 mm and the maximum wall thickness of 38.1mm. This kind of pipe making equipment should be accompanied by wide plate mill to obtain high quality and high mechanical properties of raw materials.
⑩ Mini MPM (continuous pipe mill with less stand and limited power).
Recently, a new type of limited action continuous rolling mill is put forward abroad, which consists of 4 ~ 5 stands. By using the cone-shaped taphole mill, a large elongation coefficient can be achieved, so as to reduce the deformation of the continuous rolling mill. It is similar to neuvall R, which was put forward by French company in the early 1980s. Although the models have not been put into practice, there will be no technical risk.
⑪ Hybrid drive tension reducing mill.
The transmission system of one tension reducing mill consists of two independent transmission systems. Some of the racks on the inlet side are driven by double motor differential speed transmission. Some of the racks on the outlet side are driven by DC motor alone, which has the advantages of two kinds of power transmission systems. At present, no prototype has been put into production.
Suggestions on the development of steel pipe production technology in China
In recent years, some of the steel pipe production technologies developed abroad have been introduced into China and some are under development. In order to make our steel pipe products meet the needs of technical progress of various industries in terms of variety and quality, and to be competitive in the market, it is necessary to improve our equipment level by one step, transform the old rolling mill with new technology and equipment, and build the first-class new rolling mill in the world.
① In foreign countries, small and medium-sized automatic pipe rolling mills tend to be eliminated gradually, while large-scale rolling mills are reformed.
In view of the special situation in China, the large-scale rolling mill can be reformed on the basis of the original one. The single pass rolling mill can replace the multi pass rolling mill, strengthen the capacity of the whole mill, and increase the necessary detection means. For the Φ 140mm automatic pipe rolling mill, it is necessary to adopt the appropriate machine type to make the product quality reach the international advanced level. For a large number of Φ 76mm and Φ 100mm units, due to the backward technology and equipment, in addition to the fact that some workshops with raw material conditions can be transformed into workshops that mainly produce small-diameter ordinary steel pipes and appropriately expand their scale, some workshops can also be transformed into high-grade cold drawn pipes with high, precise, sharp and fine quality, instead of producing ordinary cold drawn pipes. Important varieties with large demand should be produced in modern workshops.
② The medium-sized pilger mill can be retrofitted with a small stand limited moving continuous rolling mill with a scale of about 30 × 104 t to produce small-diameter hot-rolled seamless steel pipes. It can not only make the products of Chengdu Steel Pipe Plant match in specifications, but also fill the gap after the production reduction of cold drawn common pipes. In order to produce large, medium diameter and thick wall steel pipes, it is necessary to increase the product specification of pilger mill and add some on-line heat treatment and testing equipment.
③ The Φ 140 mm continuous rolling mill was built in the early 1980s when the production technology of the slotted steel pipe changed dramatically. Its equipment and technology level are higher than other seamless steel pipe mills, but compared with the international advanced level, there is still a gap, and the rolling blank is used as the raw material. It is necessary to study the possibility of changing the full floating mandrel into the limited moving mandrel, if possible, to improve the quality of the product; if not, to improve or reform the speed control system of the pipe rolling machine and the tension reducer, to produce according to the original design product scheme, so as to improve the dimensional accuracy and the yield of the product.
④ In the resistance welding pipe machine with diameter ≥ 101.60mm, heat treatment equipment and flaw detection equipment shall be added for those with higher equipment level, and the State shall supply the strip steel meeting the variety requirements to promote its production of high-grade products. Most small units still produce water gas pipes, but they should be equipped with a certain amount of hot-dip tracing equipment, and ensure the quality of hot-dip steel pipes.
⑤ In order to make the quality of steel pipes competitive in the market and reach the quality level of the main foreign steel pipe manufacturers, in addition to advanced technology and excellent equipment, it is necessary to have high-quality raw materials and excellent operation and management level. It is necessary to develop steel grades that meet the needs of various varieties. The steel pipe rolling mill shall have its own fixed raw material base. It is not beneficial for variety, quality and benefit to adjust the rolling stock. The structure of specialization, centralization, miniaturization and decentralization in steel pipe production is difficult to realize variety development, quality improvement, benefit growth and technology progress.
Source: Network Arrangement – China Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.steeljrv.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
If you want to have more information about the article or you want to share your opinion with us, contact us at firstname.lastname@example.org
Please notice that you might be interested in the other technical articles we’ve published:
- How to get high quality stainless steel pipes
- What is the difference between a steel pipe and a steel tube
- Engineering Specification for Pressure Test of Piping System
- How To Distinguish Inferior Steel Pipe
- How to get high quality steel pipes
- Manufacturing process of cold rolled steel pipe
- How to get high quality boiler tubes
- What is thick-walled steel pipe
- How to get high quality alloy steel pipes
- How to get high quality pipe fittings
- How to get high quality heat exchanger tubes
- The difference between steel tubes and steel pipes
- THE DIFFERENCE BETWEEN STEEL TUBES AND STEEL PIPES
- Difference between welded steel pipe and seamless steel pipe
- Characteristics of seamless steel pipes