Seamless steel pipes - one of the basic structural elements of the petroleum industry pipelines device Distribution Communications housing complex, used in construction, engineering and other sectors of the economy. Seamless steel pipes made of various assortments of Hot GOST or technical conditions (TU).
Compliance with technical requirements, quality workmanship with modern technologies, the strength characteristics of manufactured products allow you to select from the assortment of manufactured products for a wide variety of designs in accordance with the necessary properties.
Manufacturing technology
Hot seamless pipe produced by a general purpose screw hot rolling billets of carbon or alloy steel for interstate GOST standard 32528-2013.
The range of products manufactured by the enterprise directly depends on the capacity of the production equipment, production technology. GOST provides range of pipes with an outer diameter of 20-550 mm, a wall thickness of 2.5-75 mm.
When ordering, set all customer requirements within the standard equipment features
The enterprise produces the product range of a set of mix under GOST, general purpose, and carries out individual orders from various industries. In addition to standards, the customer establishes additional requirements consistent with the purpose and conditions of use of its products.
The manufacturer produces products from the standard range of steel grades or conditions imposed by the customer. The technological process of manufacturing seamless hot articles in rolling mills is performed stepwise, with the movement of the workpiece conveying method. Each of the processes of the product, promoting billet mill line Automation of fully.
Preparatory stage
Raw materials used to produce the product comes from the steel companies in the form of forged, rolled, extruded or continuously cast billets (rods or bars and rods of circular cross section). With the party passport necessarily come.
Before serving production, rods selectively inspected visually weighted. Possible defects are eliminated. Products are supplied to the loading bars.
The heating of the preform, cutting the cut length
To heat the workpiece to a temperature at which it acquires the required ductility for further processing, the mill used in walking beam furnace (PN sequence). stacking algorithm is simultaneously present in the furnace depends on the setting preforms volume planting places on the rolling mill line rate, long rods, steel grade.
Moving the preforms over the hearth furnace passes in discrete steps preheating cycle, determined by the time of heating steels to a plastic state. Step is set according to the maximum time.
For various steels or length preforms to the cycle time is adjusted landing displacement of first elements party. When the rolling rate changes on a line of planned or unexpected stops landing stops, temperature and pressure reduced in the furnace, the workpiece stands back by the required number of steps or discharged completely from the latter zones heating.
The successful treatment of a workpiece fed to the furnace hot cutting line to the mobile abutment, cut with scissors to the desired cut length.
The steps of forming tubes
The process of forming a seamless hot-selling based on a set of successive processing stages in the process equipment mill. In each subsequent processing step the product is fed conveyor line.
Stepwise formation of the finished product is divided into the following stages:
- Firmware preform receiving sleeve for further rolling. The heated preform is fed into a deformation zone centered. Firmware mandrel bar is retained in the core. The centering rollers mounted parallel to the rod axis, is prevented from buckling under axial loads. As a result - of the sleeve blank is formed with an opening necessary for the subsequent calibration diameter.
- Forming rough pipe body. The sleeve is supplied to the receiving trough of the rolling mill, it is administered in a long mandrel of appropriate diameter. Here, the mandrel sleeve is captured within the pulling rollers, it passes through the continuous rolling mill stand. Unrolling takes place discrete body blank swath calibres with roller cage until the desired wall thickness of the pipe for roughing.
- The reduction and calibration. The resulting rough pipe is subjected to induction heating, it is fed to the reducing mill. Passing through the reduction stand 24, blister tube receives final calibration characteristics of the finished product, the tails are cut loose.
- The final stage. The obtained tube is cooled, shaped into horizontal packages are cut to length, processed anticorrosive composition. Before shipment to the warehouse of finished products, products are PTA, are marked.
Received in a rolling mill with automatic control program Hot pipes fully meet the requirements of state standards.
Range pipes, geometric characteristics and tolerances
As a result of the described production cycles in the mill obtained the corresponding GOST 32528-2013 seamless hot tube:
- general purpose multiple dimensional approximate length of from 4 to 12.5 m with a tolerance of ± 5 cm;
- dimensional, with a tolerance of, respectively, GOST standards. TU enterprises allow release tube fixed-size up to 6 meters in length with a tolerance of + -10 mm, more than 6 meters with a diameter <152 mm tolerance of ± 15 mm.
According to the standard parameters GOST 32528-2013 item 5.1 of quality products, manufactured by enterprises of the pipe:
- Group A with the normalized mechanical properties of ultimate strength, yield strength, elongation, hardness.
- Group B - normalized chemical composition and type of steel on the degree of doping of carbon content and other components.
- Group B - set standards as the mechanical characteristics and the chemical composition of steel grades.
- Group D - controlled mechanical properties, heat treatment regimes.
Another feature that is used by specialists shows coefficient (k) relationship of the outer diameter of the product (D) to the wall thickness (h) - k = D / h:
- at 12.5 k <40 - Pipe is considered a thin-walled;
- 6
- k <6 - reinforced.
The range of products recommended for producers to GOST 32528-2013, provides products with an outside diameter of 20-550 mm, wall thickness of 2.5-75 mm. Full gauge table showing the nominal mass of 1 meter tube in accordance with the outer diameter and wall thickness, refer to paragraph 4 GOST.
Nominal figures differ from the actual depending upon the grade of steel. Values with asterisk tables are available when ordering the enterprise. In the field with a minus sign indicates that the product with these settings are not made.
tolerances
The production process of hot-rolled seamless pipes complicated, however GOST allows some deviation from standard geometric specifications for general purpose products.
- Deviations OD-precision products: when d <50 mm tolerance ± 0.5 mm 50
219 mm - 1.0%. - Variations in wall thickness precision conventional products: from +12.5% to -15% when the wall thickness of h <15 mm, ± 12.5% if 15
30 mm. Check provides for the manufacture of pipes with a combination of tolerances, for example single-precision wall thickness, increased at the outer and inner diameter, ovality. - The curvature of 1 meter of pipe: 1.5 mm when h <20 mm, 2.0 mm at 20
30 mm. The total curvature of the product is evaluated as <2% of the length. - The ends of the tubes are cut vertically bevelled at an angle of> 70 degrees. In the case of hot-welding of seamless pipes in the field, the customer may assign a bevel angle and a thickness of the end ring.
- Customer may agree with the manufacturer additional tests on the product batch pressure bending, flattening by chemical composition and macrostructures using the standard equipment.
Materials and physical characteristics of the product
Physical properties of hot seamless pipe directly dependent on the properties of the steel from which they are produced. For manufacturing enterprises or products used carbon steel alloy.
Carbon steel
The material has a higher carbon content (> 0.12%) in the alloy. The production of this kind of steel is characterized by a relatively low cost, so the cost of goods less than stainless steel.
GOST allows entry into the alloy nonmetallic impurities. According to its characteristics and purpose, carbon steel is divided into groups:
- Group A. Of this group of alloys is produced without hot working products while maintaining the mechanical properties.
- Group B is used for hot-rolled products. Depending on the chemical composition of the steel used various methods of manufacture of products, thus changing certain mechanical properties and structure.
- Group B is used in the production of pipes with welded joint.
Articles made from medium carbon steels have a high degree of hardness, strength, wear resistance.
Alloy steel
This name has received an alloy of iron with a carbon content <0.12%, having alloying elements in the composition. Components allow to reach preset parameters mechanical, chemical properties defining further steels appointment and manufactured products of them. to the content of alloying elements and characteristics of standardized requirements of GOST 5632-72.
Main items related to the doping - chromium, vanadium, copper, manganese, nickel, silicon. Depending on the percentage of the alloy components in the formula, is prepared heat-resistant, corrosion-resistant high-alloy (10-50% of the alloying elements) or low-alloyed chromium steel.
Pipes obtained from alloy steel having improved technical and operational characteristics:
- Durability - is achieved at a lower temperature, increased thermal tempering duration than carbon steel, high carbon content in the formula of the alloy, silicon.
- Hardness, wear resistance is achieved by increasing the content of chromium, vanadium, manganese.
- Acid resistance is determined by the amount of silicon alloy special treatment.
- Corrosion resistance, low cold cracking is prepared by adding a nickel chromium steel.
- Addition of formula to 7% tungsten, molybdenum, boron allows for Hot tube at temperatures up to 1100 degrees.
The marking of products to the requirements of the party
Hot-formed seamless pipes in packages available by weight for transport, but not more than:
- 400 pieces of products with a diameter <76 mm;
- 200 pieces of larger diameter.
In accordance with GOST 32528-2013, paragraph 6.1, the pipe must be the same party:
- one nominal size diameter, wall thickness;
- products must be manufactured from one grade of steel with the same chemical composition;
- accompanied by a passport-quality and a tag on each packet.
Marking of hot pipes must comply with GOST. Marking example: 102 * 12 * 6000 - B - 40X GOST 32528-2013. Transcript:
- pipe having an outer diameter of 102 mm;
- 12 mm wall thickness;
- length of 6 meters with high accuracy geometric characteristics;
- steel grade 40X;
- made by Group B GOST 32528-2013 requirements.
In addition, it states the manufacturer and details of the beneficiary.
Manufacturers, the cost of production
In Russia launched production of hot-rolled seamless pipes at such leading companies as:
- TK "Profile AKRASIA";
- Almetyevsk TK;
- "Azovstal";
- GC "Demidov";
- Cherepovets ChTPZ;
- ChTPZ, Chelyabinsk;
- Pervouralsky PNTZ et al.
The following are nominal prices for the most popular products are publicly available as of November 2018.
| Diameter products |
Thickness wall |
Mark become |
The weight N 1 / m |
Price for 1 meter |
| 38 | 4 | Article 20 | 3,5 | 605 |
| 60 | 6 | Article 20 | 7,99 | 862 |
| 73 | 8 | Article 20 | 12,82 | 1346 |
| 89 | 7 | Article 20 | 14,16 | 1400 |
| 102 | 8 | Article 20 | 18,55 | 1843 |
| 114 | 10 | Article 20 | 25,65 | 2262 |
| 146 | 14 | Article 20 | 45,57 | 3535 |
Areas of use
Assortment offered by manufacturers as the public is divided on the purpose for use of 6 classes:
- The usual rental for fences, poles, water diversion lines.
- Rental from carbon steel intended for network and main pipelines.
- Rental, devices used for systems operating under high pressure.
- Products for the oil and gas industry. This casing strings, drill pipe. Products mark "K" of steel 37G2S withstand internal pressures up to 400 bar, are used in fracturing formations.
- Rent for the manufacture of high-strength structures.
- Manufactured parts of rings, cylinders, mechanisms responsible nodes.
Hot seamless pipe, despite the high cost, are used in many industries industry, where maximum strength is required fabricated structures, pressurized work or aggressive environment.
