RU2522512C1 - PRODUCTION OF 299×10-60 mm SEAMLESS HOT-ROLLED PIPES FOR STEAM BOILERS, STEAM PIPELINES AND MANIFOLDS OF PLANTS WITH HIGH AND SUPERHIGH STEAM PARAMETERS OF "10Х9МФБ-Ш"-GRADE STEEL - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention relates to metallurgy, particularly, to pipe rolling. Hollow ESR ingots are bores and turned to hollow billets sized to 500xvn.320x3200±50 mm. Said hollow billets are heated to 1180-1200°C and rolled at PRU 8-16" with Pilger rerolled hot-rolled pipes sized to 325x15x20300-20700 and 325x18x17600-18300 mm. Process wastes are cut off by hot-cutting saw, hot-rolled rerolled pipes are cut to lengths. The latter are straightened at six-roll straightener and subjected to heat treatment. They are accepted and rolled at CRM 450 to cold-rolled pipes sized to 299x10-15 mm.

EFFECT: higher mechanical properties and precision of pipe sizes.

3 cl, 1 tbl

Description

The invention relates to pipe rolling production, and in particular to a method for the production of seamless pipes of 299 × 10-15 mm in size for steam boilers, steam pipelines and manifolds of installations with high and supercritical steam parameters from 10Kh9MFB-Sh steel and can be used on a pipe rolling installation 8-16 ′ ′ With pilgrim mills in the manufacture of 325 × 15 and 325 × 18 mm conversion pipes from hollow ingots-billets of electroslag remelting (ESR), for their subsequent rolling at the KhPT 450 mill into commodity pipes of 299 × 10-15 mm in size.

In the practice of pipe production, there is a method of manufacturing boiler pipes of large and medium diameters from forged billets of steels of grades 20, 15GS, 15XM, 12X1MF, 15X1M1F, 12X2MFSR, 10X9MFB, 12X11V2MF, 08X16H9M2, 12X18N12T, 10Kh13G12B2K2 with mechanical properties that include forging them into forgings (compaction of the structure) with a yoke of ≥2.5, machining the forgings into billets (turning with metal removal of 10-15 mm per side), drilling in the blanks of a central hole with a diameter of 100 ± 5 mm to remove the central quatational porosity and nonmetallic inclusions, heating the workpieces to ductility temperature, piercing the workpieces in cross-helical mills into sleeves, rolling the sleeves into tubes with a diameter of 245-550 mm on a pilgrim installation 8-16 ″ with a diameter tolerance of + 1.25 / - 1,0 and wall thickness + 25 / -5% (TU 14-1-2560-78 "Forged pipe billets for boiler pipes", TU 14-3-460-2003 and TU 14-3P-55-2001 "Steel pipes seamless for steam boilers and pipelines ”and TU 14-3-420-75“ Pipes for steam boilers and pipelines made of steel 15GS and 15Kh1M1F ”).

The disadvantage of this method is the high energy intensity of the process associated with heating and deformation (forging) of the ingots into forgings, followed by turning and drilling of the central hole, heating the workpieces to a plasticity temperature, piercing and rolling them into pipes on pilgrim mills with a wall tolerance of + 20 / - 5%, increased consumption coefficient of the metal during the conversion of the ingot-forging-billet-pipe and, as a consequence, the high cost of the pipes, as well as the fact that this steel grade, although included in TU 14-3P-55-2001, but the pipes to the last mom nt were not made from it.

In pipe production, there is a known method for manufacturing large diameter gas lift pipes from 09G2S steel ingots for the production of ESR and VDP (patent RU No. 2119395, Cl. B21B 19/04), where the ingots are deformed in the piercing mill along the location of the crystals, setting the ingots in the mill with the head part, and stitched with a posad in diameter by the amount

D = 2S _g (1-sinα) / S _c ,

where S _g - wall thickness of the sleeve, mm;

S _c - wall thickness of the drilled ingot ESR, mm;

α is the angle of inclination of the crystallization front to the axis of the ingot, deg.

The disadvantage of this method of manufacturing large diameter pipes from ingots of ESR and VDP steel grade 09G2S is the need to manufacture macro templates to determine the angle of inclination of the crystallization front to the axis of the ingot, and the piercing of the ingots with shrink (head) part forward leads to the formation of defects in the form of internal captures at the front ends of the sleeves .

In pipe production, there is also known a method for the production of large diameter boiler pipes from ESR ingots (patent RU No. 2180874, Cl. B21B 19/04), which reduces energy consumption, reduces metal consumption and, as a result, reduces the cost of boiler pipes by using larger diameter ingots and conducting the firmware process with a posad in diameter equal to 8-16%.

The disadvantage of this method is that due to the low power of the drive of the piercing mill of ChTPZ OJSC, ESR ingots from this brand began to be stitched with a seam with a diameter of 8-16%, it is not possible.

In pipe production, there is also known a method for the production of hot-rolled conversion and commodity pipes of large and medium diameters from hard-to-deform grades of steel and alloys in tube rolling plants with pilgrim mills (patent RU No. 2278750, Cl. B21B 21/00), including turning of ESR ingots and forged billets, drilling a central hole with a diameter of 100 ± 5 mm, heating them to a plasticity temperature, piercing them with subsequent rolling in a cross-helical mill into shells and rolling the shells in a pilgrim mill into hot-rolled processing pipes or pipes with a relatively thick wall, with the first piercing of ESR ingots and forged billets in a cross-helical rolling mill with the bottom end forward, and the second piercing-rolling with the shrink end forward, the pipes are rolled on a pilgrim mill with diameter to the wall thickness D / S = 6.5-8.0 with a hood µ≤4.5.

The disadvantage of this method is that it includes heating the ESR ingots and billets to a temperature of ductility, flashing them in a cross-helical rolling mill into billet sleeves, reheating the billet blanks from a cold or hot embankment to a ductility temperature, flashing-rolling in the mill cross-helical rolling into sleeves with their subsequent rolling in a pilgrim mill to commodity or conversion pipes. Double heating leads to double burning of the metal, and the flashing of ESR ingots and billets into blanks-blanks with their subsequent rolling into sleeves leads to a 2-fold loss in the performance of the pilgrim installation and, consequently, to an increase in the cost of commodity and conversion pipes. This method extends to the production of seamless hot-deformed conversion and commodity pipes of large and medium diameters in tube-rolling plants with pilgrim mills from hard-deformed grades of steel and alloys and does not provide for the production of boiler tubes from solid and hollow ingots-blanks EShP steel grade 10X9MFB-Sh.

The closest technical solution is a method for preparing billets for rolling commodity and conversion pipes of large and medium diameters from hard-to-deform grades of steel and alloys in tube rolling plants with pilgrim mills (patent RU No. 2340417, Cl. B21B 21/00), including the casting of hollow ingots by electroslag remelting , turning and boring them into hollow ingots-blanks with metal removal, the value of which is determined from the expressions Δ = K ∗ D / S, Δ ₁ = K ₁ ∗ D / S, where Δ is the value of the metal layer to be removed when turning hollow ESR ingots, mm; Δ ₁ - the value of the removed metal layer when boring hollow ingots ESR, mm; D is the outer diameter of the hollow ingots, mm; S is the wall thickness of the hollow ingots, mm; K = 0.3-0.4 - coefficient for determining the magnitude of the removed metal layer during turning of hollow ingots of ESR, large values of which relate to steels with a high content of alloying elements; K ₁ = 0.4-0.5 is the coefficient for determining the size of the metal layer to be removed during the boring of hollow ingots, the high values of which relate to steels with a high content of alloying elements, and the bottom of the hollow ingots of ESR is removed by anode-mechanical cutting, the value of which is determined from the expression LK ₂ ∗ D / S, where K ₂ = 15-20 is the coefficient for determining the magnitude of the removed bottom of the ingots, large values of which relate to steels with a high content of alloying elements.

The disadvantage of this method is that it is aimed at the technology of converting hollow ESR ingots into hollow ingots-blanks for the production of pipes from hardly deformable steel and alloy grades and does not solve the technological issues of the production of seamless commodity pipes for steam boilers, steam pipelines and collectors of installations with high and supercritical parameters made of steel grade 10X9MFB-Sh with a diameter of 299 mm with wall thicknesses from 10 to 15 mm.

Pipes with a diameter of 299 mm in Russia can only be produced on TPU 8-16 ″ with pilgrim mills and on the HPT 450 mill.

Rolling pipes 299 × 10-15 mm in size on TPU 8-16 ″ with pilgrim mills is problematic due to the low temperature of 10Kh9MFB-Sh steel under a deformation of 1180-1200 ° C. For rolling pipes of 299 × 10-15 mm in size, ESR ingots-blanks of 470 × 100 × 1750 mm in size are required, of which it is theoretically possible to roll a 299 × 10 mm pipe up to 27 meters in length on a pilgrim mill. The rolling time of such a pipe from a sleeve with a size of 470hvn. 315 × 2890-3050 mm with a wall thickness of 77.5 mm is more than 4.5 minutes. For this period of time, the sleeve tube with a wall thickness of 77.5 mm cools down to 750-800 ° C (at a recommended minimum of 850 ° C at the end of rolling). Rolling pipes and rolling in pilgrim heads made of 10Kh9MFB-Sh steel at temperatures below 850 ° C leads to increased loads on the pilgrim mill drive and tightening the mandrels, which, in turn, can lead to breakdown of the safety bolts and spindles of the pilgrim mill, lowering productivity of the mill by removing the mandrels due to puffs, replacing safety bolts and spindles. To reduce the number of puffs, it was necessary to roll pipes from this brand on mandrels with a taper of 4-5 mm, instead of a taper of 1.0 mm, which would lead to longitudinal delta and increased rejection of pipes along the wall. Thus, rolling commercial tubes of 299 × 10-15 mm in size made of 10Kh9MFB-Sh steel at TPU 8-16 ″ with pilgrim mills is impractical. Pipes of this size are currently produced from redistribution pipes measuring 316 × 27-32 mm, followed by machining, turning and boring them to a size of 299 × 10-15 mm, respectively.

The objective of the proposed method (invention) is the development of TPU 8-16 ″ with pilgrim mills for the production of seamless hot-rolled seamless tubes of size 325 × 15 and 325 × 18 mm from hollow ingots-blanks of electroslag remelting with a size of 500 × ext. 320 × 3200 ± 50 mm for their subsequent rolling at the KhPT 450 mill into commodity ones with a size of 299 × 10-15 mm with increased requirements for mechanical properties, geometric dimensions and surface quality, reduction of metal consumption during redistribution, a hollow ingot-billet - 325 × hot rolled pipes 15 and 325 × 18 mm - seamless commodity cold-rolled boiler tubes measuring 299 × 10-15 mm, increasing the mechanical properties of metal pipes due to the fractional deformation during rolling at 8-16 -16 TPU with pilgrim mills and rolling (rolling) conversion pipes into commodity at the mill HPT 450.

The technical result is achieved by the fact that in the known method for the production of seamless pipes 299 × 10-15 mm in size for steam boilers, steam pipelines and manifolds of installations with high and supercritical parameters of steam from steel grade 10X9MFB-Sh, including the smelting of hollow ingots by electroslag remelting, machining boring and turning of hollow ingots into ingot ingots, heating of ingot blanks to the temperature of plasticity, rolling of ingot blanks in a pilgrim mill into conversion pipes, rolling of conversion pipes at X mills PT in commodity, heat treatment, ultrasonic control and pipe acceptance is characterized by the fact that pipes are produced by electroslag remelting of hollow ingots, turning and boring them into hollow ingots-blanks of size 500 × ext. 320 × 3200 ± 50 mm, heating ingots up to a temperature of 1180-1200 ° C, rolling on TPU 8-16 ″ with pilgrim mills into hot-rolled steel tubes of 325 × 15 × 20300-20700 and 325 × 18 × 17600-18300 mm sizes with hoods, respectively, µ = 7.77 and µ = 6.54, compression in diameter Δ = 36.2% and with feeds of sleeves into the deformation zone m = 15-18 mm, techno segments of natural waste-seed ends and pilgrim heads with a hot-cutting saw, cutting of hot rolled pipes 325 × 15 × 20300-20700 mm in size into three 325 × 15 × 6760-6900 mm hot pipes, and 325 × 18 × 17600 hot rolled pipes -8300 mm for two slots of equal length measuring 325 × 18 × 8800-9150 mm, straightening on a six-roll straightening machine, heat treatment, acceptance with a tolerance of + 1.25 / -1.0 in diameter and ± 12.5% wall thickness, and rolling at the KhPT 450 mill into cold-rolled commodity pipes, and the hot-rolled conversion tubes of 325 × 15 × 6760-6900 mm in size they melt at the KhPT 450 mill into commodity cold-rolled pipes of 299 × 10 × 9800-10200, 299 × 11 × 9300-9600, 299 × 12 × 8200-6600 and 299 × 13 × 7600-8000 mm sizes with hoods µ = 1.54, µ = 1.47, µ = 1.35 and µ = 1.21, respectively, and hot-rolled chimneys of 325 × 18 × 8800-9150 mm in size - into commodity cold-rolled pipes of 299 × 13 × 12700-13200, 299 × 14 × 11400-11900 and 299 × 15 × 10700-11100 mm with hoods µ = 1.49, µ = 1.34, and µ = 1.26, respectively, commodity cold-rolled pipes are subjected to heat treatment, dressing, ultrasonic inspection and pipe acceptance with tolerances of diameter ± 1.0% and wall thickness + 15 / -5%, rolling of conversion tubes of size 3 25 × 15 and 325 × 18 mm on TPU 8-16 ″ with pilgrim mills are produced from hollow ingots-blanks, the wall thicknesses of which are determined from the expression

, $$S_{s(\mathrm{one,}2)}=\frac{k{D}_s\pm \sqrt{{\left(k{D}_s\right)}^2-\mathrm{four}k{\mu }_n{S}_m{\left(D_m-S_m\right)}^2}}{2k}+{\Delta }_o+{\Delta }_p$$

,

where k = 0.98 is a coefficient that takes into account the amount of fumes of steel grade 10X9MFB-Sh when heating the metal in a methodical furnace; D _s - the outer diameter of the hollow ingot blanks, mm; D _m - the diameter of the hot-rolled conversion pipes, mm; S _m - wall thicknesses of hot-rolled conversion pipes, mm; µ _n ≥6.54 is the drawing coefficient when rolling hot rolled pipe 325 × 18 mm in size on a pilgrim mill from hollow ingots; Δ _o - allowance for turning hollow ingots into hollow ingots-blanks, mm; Δ _p is the allowance for hollow ingots into the hollow ingots-blanks, mm, and after being dispensed from the furnace before transportation to the pilgrim mill, the hollow ingots-blanks are lubricated with a mixture of graphite with sodium chloride (50/50) weighing 300-500 g .

Comparative analysis with the prototype shows that the inventive method for the production of seamless pipes 299 × 10-15 mm in size for steam boilers, steam pipelines and manifolds of installations with high and supercritical parameters of steam from 10Kh9MFB-Sh steel, differs in that the pipes are produced by electroslag remelting hollow ingots, turning and boring them into hollow ingots-blanks of size 500 × ext. 320 × 3200 ± 50 mm, heating ingots of the workpieces to a temperature of 1180-1200 ° C, rolling on TPU 8-16 ″ with pilgrim mills into hot-rolled mill 325 × 15 × 20300-20700 and 325 × 18 × 17600-18300 mm in size with hoods, respectively, µ = 7.77 and µ = 6.54, diameter reduction Δ = 36.2% and with feeds of sleeves to the focus deformations m = 15-18 mm, pieces of technological waste-seed ends and pilgrim heads with a hot cutting saw, cutting of hot rolled pipes of size 325 × 15 × 20300-20700 mm into three pipe-crates of size 325 × 15 × 6760-6900 mm, and hot rolled tubes 325 × 18 × 17600-18300 mm in size for two equal length slabs of 325 × 18 × 8800-9150 mm in size, straightenings on a six-roll straightening machine, heat treatment, acceptance with tolerance n about a diameter of + 1.25 / -1.0 and a wall thickness of ± 12.5%, and rolling at the KhPT 450 mill into commodity cold-rolled pipes, and the hot-rolled conversion pipes 325 × × 15 × 6760-6900 mm in size are rolled at the KhPT 450 mill into commodity cold-rolled pipes of size 299 × 10 × 9800-10200, 299 × 11 × 9300-9600, 299 × 12 × 8200-6600 and 299 × 13 × 7600-8000 mm with hoods µ = 1.54, µ = 1.47 , µ = 1.35 and µ = 1.21, respectively, and the hot-rolled chimneys of 325 × 18 × 8800-9150 mm in size - into commodity cold-rolled pipes of 299 × 13 × 12700-13200, 299 × 14 × 11400-11900 and 299 × 15 × 10700-11100 mm with hoods µ = 1.49, µ = 1.34, and µ = 1.26, respectively, commodity cold-rolled pipes they are subjected to heat treatment, dressing, ultrasonic inspection and acceptance of pipes with tolerances of ± 1.0% in diameter and wall thickness + 15 / -5%, rolling of conversion tubes 325 × 15 and 325 × 18 mm in size on TPU 8-16 ″ s Pilgrim mills are produced from hollow ingots-blanks, the wall thicknesses of which are determined from the expression

, где k=0,98 - коэффициент, учитывающий величину угара стали марки 10Х9МФБ-Ш при нагреве металла в методической печи; D_з - наружный диаметр полых слитков-заготовок, мм; D_m - диаметр горячекатаных передельных труб, мм; S_m - толщины стенок горячекатаных передельных труб, мм; µ_n≥6,54 - коэффициент вытяжки при прокатке передельных горячекатаных труб размером 325×18 мм на пилигримовом стане из полых слитков-заготовок; Δ_o - припуск на обточку полых слитков в полые слитки-заготовки, мм; Δ_p - припуск на расточку полых слитков в полые слитки-заготовки, мм, а после выдачи из печи перед транспортировкой на пилигримовый стан в полые слитки-заготовки подают смазку в виде смеси графита с поваренной солью (50/50) массой 300-500 г. Таким образом, эти отличия позволяют сделать вывод о соответствии критерию «изобретательский уровень». $$S_{s(\mathrm{one,}2)}=\frac{k{D}_s\pm \sqrt{{\left(k{D}_s\right)}^2-\mathrm{four}k{\mu }_n{S}_m{\left(D_m-S_m\right)}^2}}{2k}+{\Delta }_o+{\Delta }_p$$

where k = 0.98 is a coefficient that takes into account the amount of fumes of steel grade 10X9MFB-Sh when heating the metal in a methodical furnace; D _s - the outer diameter of the hollow ingot blanks, mm; D _m - the diameter of the hot-rolled conversion pipes, mm; S _m - wall thicknesses of hot-rolled conversion pipes, mm; µ _n ≥6.54 is the drawing coefficient when rolling hot rolled pipe 325 × 18 mm in size on a pilgrim mill from hollow ingots; Δ _o - allowance for turning hollow ingots into hollow ingots-blanks, mm; Δ _p is the allowance for hollow ingots into the hollow ingots-blanks, mm, and after being dispensed from the furnace before transportation to the pilgrim mill, the hollow ingots-blanks are lubricated with a mixture of graphite with sodium chloride (50/50) weighing 300-500 g Thus, these differences allow us to conclude that the criterion of "inventive step" is met.

Comparison of the proposed method not only with the prototype, but also with other technical solutions in the art did not allow them to identify signs that distinguish the claimed method from the prototype, which corresponds to patentability "inventive step".

The proposed method for the production of seamless pipes of 299 × 10-15 mm in size for steam boilers, steam pipelines and manifolds of plants with high and supercritical steam parameters made of 10Kh9MFB-Sh steel was implemented at TPU 8-16 ″ with pilgrim mills in the manufacture of 325 hot rolled pipe × 15 mm and rolling them on the mill ХПТ 450 into commodity cold-rolled pipes 299 × 11 mm in size.

According to the existing method, the production of seamless hot-rolled pipes of 299 × 11 mm in size is carried out by machining, boring and turning the conversion pipes of 316 × 30 mm in size. Converting pipes 316 × 30 mm in size are produced from ESR ingots-blanks of 500 × 100 × 1750 ± 50 mm in size according to the technology: ingot-blanks are heated in a methodical furnace to the ductility temperature and stitched in a transverse helical mill into 470 × vn shells. 290 × 2900-3100 mm on a mandrel with a diameter of 275 mm with an exhaust hood µ = 1.72 and a diameter fit Δ = 6.0%; the sleeves are rolled on TPU 8-16 ″ with pilgrim mills into redistribution pipes 316 × 30 × 10,000 -10,800 mm in size; Converting pipes are cut into two slots of equal length, grinded and bored into commodity pipes measuring 299 × 11 × 5200-5400 mm. According to this technology, 5 ESR ingots-blanks with a total weight of 12.950 tons were set into production, of which ten pipes of 299 × 11 × 5200-5400 mm in size with a total weight of 4.360 tons were made in accordance with TU 14-3P-55-2001. The expenditure coefficient of the metal in the pipes of this batch was 2.970. According to the proposed method, the rolling of commodity pipes of size 299 × 11 mm was carried out according to the technology: hollow ingot blanks ESRs with a size of 500 × ext. 320 × 3200 ± 50 mm were heated in a methodical furnace to a temperature of 1180-1200 ° C and rolled on TPU 8-16 ′ ′ With pilgrim mills into conversion pipes of 325 × 15 × 20,000–20,700 mm in size with a fume hood = 7.77, diameter reduction of 36.2% and with feeds of sleeves into the deformation zone 16–18 mm; technological waste was cut off from the pipes by a hot cutting saw — seed ends and pilgrim heads; the pipes were cut into three pipes of equal length, the pipes were straightened, heat-treated and accepted with a tolerance of + 1.25 / -1.0 in diameter and ± 12.5% wall thickness; 325 × 15 × 6650-6900 mm conversion pipes were rolled on the KhPT 450 mill to 299 × 11 × 9300-9600 mm commodity pipes with a draft of µ = 1.47 and a compression in diameter of 8.0%; the pipes were fixed, underwent heat treatment, ultrasonic testing and acceptance of pipes by diameter ± 1.0% and wall thickness + 15.0 / -5.0% (claim 1). Five hollow ingot blanks with a total mass of 14.599 tons were assigned to production. Fifteen pipes with a size of 299 × 11 × 9300-9600 mm with a total weight of 11.889 tons were adopted in accordance with TU 14-3P-55-2001. The expenditure coefficient of the metal in the pipes of this batch was 1.227. By the proposed method, a decrease in the expenditure coefficient of the metal by 2.42 times is obtained. Hot-rolled steel tubes 325x15 mm in size were produced in accordance with claim 1 of the claims from hollow ingots-blanks made from hollow ESR ingots cast at OAO EMZ in accordance with claim 2. After discharge from the furnace in order to reduce the oxidation of the inner surface (formation of secondary scale) and the grease of the mandrels, the grease was fed into the hollow ingot blanks in accordance with claim 3.

Data on rolling conversion of 316 × 30 mm in size from 10Kh9MFB-Sh steel to TPU 8-16 ″ with pilgrim mills, machining of conversion pipes into commodity pipes of 299 × 11 mm (existing technology), conversion pipes of 325 × 15 mm and rolling (rolling) them at the KhPT 450 mill of ChTPZ OJSC into commodity pipes 299 × 11 mm in size (proposed technology) are shown in the table.

Thus, the use of the proposed method will allow for the first time in Russia to carry out production at the TPU 8-16 ″ with pilgrim mills of 325 × 15 and 325 × 18 mm size pipes for their subsequent rolling at the KhPT 450 mill into 299 × 10 commodity seamless cold-rolled pipes -15 mm for steam boilers, steam pipelines and manifolds of installations with high and supercritical steam parameters with mechanical properties of the metal and geometric dimensions that exceed the values of these indicators given in TU 14-3P-55-2001, which will allow to significantly reduce energy consumption by eliminating the process of flashing ingots-billets into sleeves during rolling of conversion pipes, significantly reduce the expenditure coefficient of metal during redistribution of a hollow ingot ESR-hollow billet-boiler conversion pipe-boiler commodity pipe, increase the productivity of TPU 8-16 '' with pilgrim camps, and, therefore, reduce the cost of boiler pipes.

Claims (3)

1. Method for the production of seamless pipes 299x10-15 mm in size for steam boilers, steam pipelines and manifolds of installations with high and supercritical steam parameters from 10Kh9MFB-Sh steel, including the smelting of hollow ingots by electroslag remelting, turning and boring them into hollow ingots-blanks of 500hvn size .320х3200 ± 50 mm, heating of ingots - billets to a temperature of 1180-1200 ^о С, rolling at 8-16 "TPU with pilgrim mills into hot-rolled chimneys of 325х15х20300-20700 and 325х18х17600-18300 mm in size with hoods, respectively µ = 7.77 and µ = 6.54, compression by dia 36,2%, and with feeds of sleeves into the deformation zone m = 15-18 mm, a piece of technological waste - seed ends and pilgrim heads with a hot cutting saw, cutting hot rolled pipes of 325x15x20300-20700 mm in size into three pipes - 325x15x6650-6900 krat mm, and hot-rolled chimneys measuring 325x18x17600-18300 mm in two equal lengths of 325x18x8800-9150 mm in length, straightening on a six-roll straightening machine, heat treatment, acceptance with a tolerance of + 1.25 / -1.0 in diameter and ± 12 wall thickness , 5%, and rolling at the mill ХПТ 450 into commodity cold-rolled pipes s, moreover, hot rolled hot-rolled pipes of 325x15x6650-6900 mm in size are rolled at the KhPT 450 mill into commodity cold-rolled pipes of 299х10х9800-10200, 299х11х9300-9600, 299х12х8200-6600 and 299х13х7600-800 mm in size with hoods µ = 1.54, µ = 1.47 , µ = 1.35, µ = 1.21, respectively, and hot-rolled chimneys measuring 325x18x8800-9150 mm into commodity cold-rolled pipes 299x13x12700-13200, 299x14x1140-11900 and 299x15x10700-11100 mm in size with hoods µ = 1.49, µ = 1.34, μ = 1.26, respectively, commodity cold-rolled pipes are subjected to heat treatment, dressing, ultrasonic inspection and acceptance with tolerances of diameter ± 1 , 0% and wall thickness + 15 / -5%. 2. The method according to p. 1, characterized in that the rolling pigs of 325 × 15 and 325 × 18 mm in size on TPU 8-16 '' with piligim mills are made from hollow ingots, the wall thicknesses of which are determined from the expression:

,

where k = 0.98 is a coefficient that takes into account the value of the fume when heating the metal in a methodical furnace,
D _s - the outer diameter of the hollow ingot blanks, mm,
D _m - the diameter of the hot rolled pipe, mm,
S _m - wall thickness of the hot rolled pipe, mm,
µ _n ≥6.54 - the minimum drawing coefficient when rolling hot-rolled pig tubes of 325x18 mm in size on a pilgrim mill from hollow ingots,
Δ _o - allowance for turning hollow ingots into hollow ingots-blanks, mm,
Δ _p - allowance for hollow ingots into hollow ingots-blanks, mm 3. The method according to p. 1, characterized in that after dispensing from the furnace, before transportation to the pilgrim mill, grease in the form of a mixture of graphite with sodium chloride (50/50) weighing 300-500 g is fed into hollow ingots.