RU2836250C1 - METHOD FOR PRODUCTION OF HEXAGONAL PIPE BILLETS WITH TURNKEY SIZE 257+2.0/-3.0×6+2.0/-1.0×4300+80/-20 mm FROM LOW-PLASTICITY STEEL GRADE “04Х14Т5Р2Ф” WITH BORON CONTENT FROM 2.01 TO 3.5% FOR COMPACTED STORAGE IN COOLING PONDS OF NUCLEAR POWER PLANTS AND TRANSPORTATION OF SPENT NUCLEAR FUEL - Google Patents

Abstract

FIELD: performing operations.

SUBSTANCE: invention relates to a method for production of hexagonal pipe billets with turnkey size 257+2.0/-3.0×6+2.0/-1.0×4300+80/-20 mm from low-plasticity steel of grade “04Х14Т5Р2Ф” with boron content from 2.01 to 3.5% for compacted storage in cooling ponds of nuclear power plants and transportation of spent nuclear fuel. Thin-wall pipe billets with size of 288×12×5500 mm by centrifugal casting with diameter tolerance ±0.5% and wall thickness ±5.0%. End cuttings are removed to form pipe billets with size of 288×12×5000 mm. Boring and turning are performed on machines with servo system into cylindrical pipe billets with size 284.75+2.0/-3.0×6+2/-1.0×5000 mm with medium metal removal per side during inner surface boring Δ₁=4.5 mm, and when turning the outer surface Δ₂=1.5 mm. Warm profiling of cylindrical pipe billets is performed into hexagonal pipe billets with turnkey size 257+2.0/-3.0×6.0+2.0/-1.0×4300+80/-20 mm.

EFFECT: increased efficiency and reduced consumption coefficient of boron-containing steel.

1 cl, 1 tbl

Description

The invention relates to a method for producing conversion tube blanks measuring 288x12x5500 mm by centrifugal casting from low-ductility steel grade 04X14T5R2F with a boron content of 2.01 to 3.5% for producing hexagonal tube blanks with a spanner size of 257+2.0/-3.0x6.0+2.0/-1.0x4300+80/-20 mm for compacted storage in NPP cooling pools and transportation of spent nuclear fuel, and can be used in the production of thin-walled seamless conversion tube blanks on centrifugal casting machines for subsequent conversion into hexagonal tube blanks.

In pipe production, a method is known for producing conversion pipes from low-plastic steel with a boron content of 1.3-1.8% (ChS 82), which involves smelting steel by vacuum arc (VD), vacuum induction (VI), vacuum induction with subsequent vacuum arc remelting (ID) and plasma remelting (P) into ingots with a diameter of 460 mm, followed by their forging into rods (blanks) with a diameter of 225-230 mm and mechanical processing (turning) to a size of 215x1850-1950 mm, heating to a plasticity temperature, piercing in a piercing mill on a TPA-350 with an automatic mill into sleeves measuring 220x45x2700-2850 mm, cooling, repair, piercing on the first piercing mill into sleeves measuring 250x28x3400-3600 mm, piercing on the second mill into tubes measuring 292x13x5600-5950 mm, rolling in an automatic mill in three passes with reductions of 14.3%, 8.3%, 0.5%, respectively, and calibration in a calibration mill into pipes measuring 288x11 mm at a temperature of 850-950°C (Report on R&D "Mastering the technology for producing large-diameter hot-rolled pipes from ChS 82 steel under the conditions of TPA-350 "YuTZ", Dnepropetrovsk, 1988).

The disadvantages of this method are interstate transportation (Chelyabinsk-Nikopol-Chelyabinsk), labor-intensive operation of forging ingots with a diameter of 460 mm into rods (blanks) with a diameter of 225-230 mm with subsequent mechanical processing (turning) and cutting to size 215x1850-1950 mm, high metal consumption coefficient during the conversion of ingot - blank - hexagonal pipe-blank, equal to 6.53 and, as a consequence, high cost of conversion pipes and finished products (hexagonal pipe-blanks). The disadvantage of this method is that hexagonal steel tube blanks made of 04Kh14T3R1F steel, despite their satisfactory ability to absorb neutrons, reduce the tendency to intercrystalline corrosion and stress corrosion cracking, when used in racks of spent nuclear fuel (SNF) pools, do not ensure the safety of storage and transportation when the uranium content in it is U-235> 5%, which is explained by the low percentage of boron in its composition. The production process of hexagonal tube blanks from this steel grade includes energy-intensive and metal-intensive technological operations: casting of ESR ingots with a diameter of 460 mm, forging them into rods (blanks) with a diameter of 225-230 mm, mechanical processing (turning) to a size of 215x1850-1950 mm, heating to a plasticity temperature, piercing in a piercing mill on a TPA-350 with an automatic mill into sleeves with a size of 220x45x2700-2850 mm, cooling, repair, piercing on the first piercing mill into sleeves with a size of 250x28x3400-3600 mm, piercing on the second mill into sleeves with a size of 292x13x5600-5950 mm, rolling in an automatic mill in three passes with reductions of 14.3%, respectively, 8.3%, 0.5% and calibration in a calibration mill into pipes measuring 288x11 mm at a temperature of 850-950°C, transportation from Nikopol (Ukraine) to ChTPZ JSC (Russia), boring and turning on machines with a tracking system into cylindrical pipe blanks measuring 284.75+2.0/-3.0x6 +2/-1.0x5000-5500 mm and their warm profiling into hexagonal pipe blanks measuring “under the key” 257+2.0/-3.0x6+2.0/-1.0x4300+ 80/-20 mm, with a consumption coefficient during processing equal to 6.53 and, as a consequence, the high cost of the conversion hexagonal pipe blanks and the fact that this technological process for the production of conversion hot-rolled pipes does not solve the technological issues of production centrifugally cast cylindrical tube blanks measuring 288x12x5500 mm with a boron content of 2.01 to 3.5%.

In pipe production, a method is known for producing conversion pipe blanks for the manufacture of hexagonal sheath pipes from low-plasticity nickel-free steel with a boron content of 1.3-1.8%, including drilling a central hole with a diameter of 100±5 mm in ESR ingot blanks measuring 460-480x1600-1750 mm, heating them to a plasticity temperature, piercing in a cross-helical rolling mill into sleeves measuring 460x240x2100-2300 mm, rolling the sleeves on a pilgrim mill into pipe blanks measuring 377x88.5x3200-3600 mm, cooling the pipe blanks and repairing them (if necessary), cutting the pipe blanks into two times - blanks measuring 377x88.5x1575-1750 mm, reheating them to a temperature plasticity, piercing (rolling) in a cross-helical rolling mill into tubes measuring 400x50x2300-2550 mm, and then rolling on a pilgrim mill into conversion tubes measuring 290x12x11000-12000 mm and straightening on a straightening machine at a temperature of at least 100°C, using the rolling heating temperature (Patent of the Russian Federation No. 2226133, class B21B 21/00, 2004).

The known method has the following disadvantages. The technological process of producing conversion pipes from ChS 82 steel, including two heatings, two piercings, two rollings on a pilger mill and cutting of pipe blanks on machines into two equal cuts-blanks, is labor-intensive, requires large costs, which leads to an increase in the price of conversion pipes and, as a consequence, to an increase in the price of hexagonal pipe blanks. Rolling two cuts-blanks measuring 377x88.5x1600-1800 mm, obtained from one ingot-blank, on a pilger mill into conversion pipes measuring 290x12x11500-12500 mm leads to an increase in process waste in the form of two dummy ends and two pilger heads. In an unsteady rolling process, i.e. During the seeding and finishing (running-in) of pilgrim heads, due to the low plasticity of steel, end defects are formed in the form of longitudinal cracks and tears over a length of 0.5-0.8 meters. This leads to an increase in the metal consumption coefficient during the conversion of an ESR ingot - a conversion pipe. Rolling pipes measuring 290x12x11500-12500 mm from sleeves measuring 400x50x2300-2550 mm on a pilgrim mill for 3.0-3.5 minutes leads to a decrease in the sleeve temperature to 750°C, i.e. The rolling of pipe ends occurs at a temperature below 800°C, which is significantly lower than the lower limit of the plasticity range of this grade of steel (800-850°C), which leads to the formation of cracks under the pilgrim head over a length of 2.0-3.0 meters, and this in turn leads to single-cut rejects, since the minimum length of the pipe for profiling (conversion into a hexagon) must be no shorter than 5000 mm. The disadvantage of this method also includes the fact that hexagonal pipe blanks made of 04Kh14T3R1F steel, with a satisfactory ability to absorb neutrons, do not ensure the safety of storage and transportation when it contains uranium U-235> 5%, which is explained by the low percentage of boron in its composition and the fact that this technological process for the production of hot-rolled conversion pipes does not solve the technological issues of producing cylindrical pipe blanks, and, consequently, does not solve the production of hexagonal pipe blanks from centrifugally cast thin-walled pipe blanks measuring 288x12x5500 mm with an increased boron content.

In pipe production, a method is also known for producing conversion pipes from low-plasticity steel with a boron content of 1.3-1.8%, including casting ingots by electroslag remelting with dimensions of 480x1750±70 or 500x1675±70 mm, turning the outer surface to remove casting defects into ingot blanks with dimensions of 460±10x1750±70 or 480±10x1675±70 mm, drilling a central hole with a diameter of 100±5.0 mm, heating ingot blanks to a temperature of 1060-1090 ° C, holding at a temperature of 450-500 ° C on the grates of continuous furnaces without tilting for 90-120 minutes, heating to a temperature of 800-850 ° C at a rate of 1.8-2.0 ° C per minute, then heating to a plasticity temperature of 1060-1090°C at a rate of 2.1-2.2°C per minute with turning after 15-20 minutes, holding at this temperature for 70-80 minutes with turning at an angle of ≈ 180° after 10-15 minutes (patent RU No. 2255820, cl. B21B 21/00, B21B 21/04, 27.12.2004), piercing of ingots-blanks in a cross-helical rolling mill into sleeves measuring 470хвн.295х2370-2800 and 480хвн.295х2310-2710 mm, rolling of sleeves on a pilgrim mill with backing carbon rings measuring 480х int. 295x250-300 mm, for partial removal of pilgrim heads, into conversion pipe-strings of size, respectively, 290x12x21000-24000 and 290x12x21000-25000 mm with drawdowns, respectively, µ=10.03 and µ=10.74 and diameter reduction Δ=38.3 and Δ=39.6%, rolling of the front ends of the pipes at a length equal to 1.0-1.2 of the feeder rollback path with a wall thickness greater than the nominal by 2-3 mm, rolling of the rear ends of the pipes - under the pilgrim head at a length equal to 1.2-1.5 of the feeder rollback path with a wall thickness less than the nominal by 0.5-0.8 mm, due to the spreading and convergence of the pilgrim mill rolls (patent RU No. 2334571, cl. B21B 21/00, 27.09.2008), cutting off process waste with a hot saw - pilgrim heads and seed ends, cutting pipe strings into two pipes of equal length, straightening pipes on a six-roll straightening machine using rolling heating temperature, cutting pipes into two blanks-folds with a length of at least 5000 mm, boring and turning them to the size of 284.75 + 2.0 / - 3.0x6 + 2.0 / - 1.0 mm and warm profiling into hexagonal pipe blanks with a "wrench" size of 257 + 2.0 / - 3.0x6 + 2.0 / - 1.0x4300 + 80 / - 20 mm (TI 158-Tr.TB1-49-2007 "Manufacture of seamless hot-deformed conversion pipes from steel grade ЧС82-04Х14Т3Р1Ф-Ш").

One of the main disadvantages of this method, as well as the above-mentioned analogs, is that ESR ingots are cast in two sizes, namely, 480x1750±70 and 500x1675±70 mm, which are turned to remove casting defects into ingot blanks measuring 460±10x1750+70 or 480+10x1675±70 mm. To cast ingots of two diameters, two crystallizers are required, which are expensive tools. A central hole with a diameter of 100±5 mm is drilled in the ingot blanks. From ingots-blanks weighing from 2000 to 2365 kg, conversion pipes measuring 290x12 mm and four times the length are rolled, which leads to increased waste due to non-multiplicity, and, consequently, to an increased consumption coefficient of expensive boron-containing steel, and this method does not solve the technological issues of producing conversion thin-walled centrifugally cast pipe-blanks measuring 288x12x5500 mm from steel grade 04Kh14T5R2F with a boron content of 2.01 to 3.5%.

The closest technical solution (prototype) is the method of producing 292x12 mm conversion pipes on 8-16" TPU with pilger mills from ingots-blanks of electroslag remelting of low-plasticity steels of grades 04Kh14T3R1F-Sh and 04Kh14T5R2F-Sh with a boron content of 1.3 to 3.5% for the manufacture of hexagonal pipe blanks of the "wrench" size 257+2.0/-3.0×6+2.0/-1.0×4300+80/-20 mm for compacted storage in NPP cooling pools and transportation of spent nuclear fuel, including casting ingots by electroslag remelting of the size 480x1675±25 mm, turning into ingots-blanks of the size 470±5x1675±25 mm, drilling a through central hole with a diameter of 100±5 mm, heating ingot blanks to a temperature of 1060-1090°C, piercing in a cross-helical rolling mill into 460x295x2710-2850 mm tubes with a diameter rise Δ from 1.1 to 3.2% and a drawing µ from 1.6 to 1.7, rolling of 460x295x2710-2850 mm tubes on a pilgrim mill into 292x12x21000-22500 mm long pipes with a drawing µ = 9.2-9.3 and a diameter reduction Δ = 35.9%, removing the dummy ends and incompletely rolled pilgrim heads with a hot cutting saw, cutting pipe-knots into two pipes 10500-11250 mm long, straightening, cutting into two pipe blanks at least 5000 mm long, boring and turning into cylindrical pipe blanks. Rolling of conversion tubes on a pilgrim mill is carried out in rolls with a caliber of 295 mm with a transverse release angle on the polishing section of 26-28 ° on mandrels with a diameter of 266/267 mm with the supply of sleeves to the deformation zone during the steady-state rolling process m = 12-14 mm, boring and turning of conversion tubes measuring 292x12 mm is carried out to a size of 284.75 + 2.0 / - 3.0 x 6 + 2.0 / - 1.0 mm with metal removal to the side when boring the inner surface ∆ ₁ = 2.5 mm, when turning the outer surface ∆ ₂ = 3.5 mm, and then warm profiling is carried out into hexagonal tube blanks with a size "under the key" 257 + 2.0 / - 3.0 x 6.0 + 2.0 / - 1.0 x 4300 + 80 / - 20 mm (patent of the Russian Federation No. 2550033, published 10.05.2015, Bulletin No. 13).

The disadvantages of this prototype, as well as the above-mentioned analogues, are that the technological process of producing hexagonal tube blanks includes energy-intensive and metal-intensive technological operations: casting ingots by electroslag remelting measuring 480x1800 mm, removing the bottom parts of the ingots into ingots measuring 480x1675±25 mm, turning into ingot blanks measuring 470±5x1675±25 mm, drilling a through central hole with a diameter of 100±5 mm, heating the ingot blanks to a temperature of 1060-1090 °C, piercing in a cross-helical rolling mill into sleeves measuring 460x295x2710-2850 mm with a diameter rise Δ from 1.1 to 3.2% and drawing µ from 1.6 to 1.7, rolling of 460x295x2710-2850 mm tubes on a pilgrim mill into 292x12x21000-22500 mm long pipes with a drawing µ = 9.2 and a diameter reduction Δ = 35.9%, removing the seed ends and incompletely rolled pilgrim heads with a hot cutting saw, cutting the long pipes into two 10500-11250 mm long pipes, straightening in a six-roll straightening machine, cutting the pipes into two blank pipes at least 5000 mm long, boring and turning on machines with a tracking system into cylindrical blank pipes measuring 284.75+2/-3x6+2/-1x5000-5500 mm and warm profiling into hexagonal blank pipes measuring “under key” 257+2/-3x6+2/-1x4300+80/-20 mm and the fact that it does not solve the technological issues of production of thin-walled centrifugally cast pipe blanks measuring 288x12x5500 mm with a boron content of 2.01 to 3.5%.

The objective of the proposed method is to develop a new innovative technological process for the production of centrifugally cast conversion tube blanks measuring 288x12x5500 mm from low-plasticity steel 04Kh14T5R2F with a boron content of 2.01 to 3.5% for the manufacture of hexagonal tube blanks with a wrench size of 257+2.0/-3.0×6.0+2.0/-1.0×4300+80/-20 mm to ensure the safety of compacted storage in NPP spent fuel pools and transportation of spent nuclear fuel containing U-235> 5%, the exclusion of defect-forming technological operations from the technological process: piercing of ESR ingots-blanks in a cross-helical rolling mill into sleeves and rolling of sleeves on a pilger mill into seamless conversion tubes, reducing the share of process waste, reducing the consumption coefficient of metal by converting centrifugally cast thin-walled pipe blanks into hexagonal pipe blanks, increasing the productivity of hexagonal pipe blanks and, consequently, reducing their cost.

The technical result is achieved by the fact that thin-walled blank pipes measuring 288x12x5500 mm are manufactured by centrifugal casting with a diameter tolerance of ± 0.5% and wall thickness of ± 5.0%, the end trim is removed to form blank pipes measuring 288x12x5000 mm, boring and turning are performed on machines with a tracking system into cylindrical blank pipes measuring 284.75+2.0/-3.0x6+2/-1.0x5000 mm with an average metal removal per side during boring of the inner surface ∆ ₁ = 4.5 mm, and during turning of the outer surface ∆ ₂ = 1.5 mm, and warm profiling of cylindrical blank pipes into hexagonal blank pipes of the "wrench" size is carried out 257+2.0/-3.0x6.0+2.0/-1.0x4300+80/-20 mm.

A comparative analysis with the prototype shows that the claimed method for producing hexagonal blank pipes with a “wrench” size of 257+3.0/-2.0x6+2.0/-1.0x4300+80/-20 mm from low-ductility steel grade 04X14T5R2F with a boron content of 2.01 to 3.5% for compacted storage in NPP cooling pools and transportation of spent nuclear fuel, differs from the known method in that thin-walled blank pipes with a size of 288x12x5500 mm are manufactured by centrifugal casting with a diameter tolerance of ± 0.5% and a wall thickness of ± 5.0%, the end trim is removed to form blank pipes with a size of 288x12x5000 mm, boring and turning are performed on machines with a tracking system into cylindrical blank pipes of a size 284.75+2.0/-3.0х6+2/-1.0х5000 mm with an average metal removal per side during boring of the inner surface ∆ ₁ = 4.5 mm, and during turning of the outer surface ∆ ₂ = 1.5 mm and carry out warm profiling of cylindrical blank pipes into hexagonal blank pipes with a spanner size of 257+2.0/-3.0х6.0+2.0/-1.0х4300+80/-20 mm. Thus, these differences allow us to conclude that the criterion of "inventive step" is met.

Comparison of the claimed method, not only with the prototype, but also with other technical solutions in this field of technology, did not allow identifying in them features that distinguish the claimed method from the prototype, which corresponds to the patentability of “inventive step”.

Since hexagonal blank pipes with a size “under the key” of 257+2/-3x6+2/-1x4300+80/-20 mm with a boron content from 2.01 to 3.5% in world practice and in Russia on

are not currently produced, then, for example, Table 1 provides theoretical data on the production of hexagonal tube blanks in accordance with the prototype (RU Patent No. 2550033), the existing method and the proposed technology.

Table 1.

View
technologist. Size
ingots-
procurement.
(mm) Quantity
merged.-
procurement.
(pcs) Weight
merged.-
procurement.
(T) Flashing of sleeves Rolling of pipes and TPU 8-16ʺ Shipped.
to the workshop
№5 Size
sleeves
(mm) Diam.
frame
(mm) Coeff.
exhaust
(µ) Size
pipes
(mm) Coeff.
exhaust
(µ) Notes when
rolling Patent
№2550033 470x100
x1650 5 10,244 460хвн.295
x2740 280 1.66 292x12
x22400 9.27 Rejected twice for tears and external films 18 Creatures. 440x100
x1750 5 9,459 440хвн.295
x2950 280 1.69 290x12
x22000 7.99 Three copies were rejected due to flaws 17 Suggestion. 288x12
x5000 5 1,950 - - - - - - 5

Continuation of table 1.

Processing in workshop No. 5 Consumables
coeff.
steel Deciphering marriage (pcs) The workpiece has been delivered. Nar.
captivity Int.
captivity Wall (pcs.) (T) 2 1 1 14 2,590 3,955 2 2 0 13 2,405 3,933 1 - - 4 0.740 2,635

According to the proposed technology, 5 centrifugally cast thin-walled pipe blanks measuring 288x12x5000 mm with a total weight of 1950 kg and a boron content of 2.98% were theoretically put into production. The ingot blanks were conventionally cast at JSC NPO AKHTUBA. The ingot blanks were conventionally bored and turned at JSC ChTPZ on machines with a tracking system into cylindrical pipe blanks measuring 284.75+2/-3x6+2/-1x5000 mm, and then profiled into hexagonal pipe blanks with a wrench size of 257+2/-3x6+2/-1x4300+80/-20 mm. During inspection and acceptance, one hexagonal pipe blank was conventionally rejected due to an outer film that brought the wall thickness beyond the minus tolerance field. Four blank pipes with a total weight of 740 kg were conventionally accepted. The theoretical metal consumption coefficient was 2.635.

In accordance with patent No. 2550033, 5 ESR ingots-blanks measuring 470x1650 mm supplied by JSC ZMZ with a boron content of 2.63 to 2.76% are conditionally assigned for production. At JSC ChTPZ, they were drilled to a diameter of 100 mm, heated in a continuous furnace to a temperature of 1070-1080°C, pierced in a cross-helical rolling mill on a mandrel with a diameter of 280 mm into sleeves measuring 460xvn.295x2740 mm with drawings of µ = 1.65 and a diameter fit of ∆ = 2.1%. The sleeves are rolled into conversion pipes measuring 292x12x22400 mm on mandrels with a diameter of 266/267 mm with a diameter fit of 35.9%. 10 pipes measuring 292x12x11200 mm were accepted according to STP 158-31 and sent to workshop #5 for mechanical processing - boring and turning into round conversion pipes measuring 284.75+2.0/-3.0×6.0+2.0/-1.0 for subsequent processing into hexagonal pipe blanks. During preliminary inspection and acceptance, two blanks were rejected for tears and external films. 18 blanks were specified for mechanical processing and profiling. During acceptance, two hexagonal pipe blanks were rejected for external films, one for internal films and one for a wall that brought the wall thickness beyond the minus tolerance field. 14 hexagonal pipe blanks with a total weight of 740 kg were conditionally accepted. The metal consumption coefficient of the ESR ingot-blank - hexagonal pipe-blank for this batch was 3.955.

According to the existing technology, 5 ESR ingots-blanks measuring 440x1750 mm supplied by PJSC Ruspolymet with a boron content of 2.58 to 2.85% are conditionally assigned for production. They were drilled at JSC ChTPZ to a diameter of 100 mm, heated in a continuous furnace to a temperature of 1070-1080°C, pierced in a cross-helical rolling mill on a mandrel with a diameter of 280 mm into sleeves measuring 440xvn.295x2950 mm with drawings µ = 1.69. The sleeves are rolled into conversion pipes measuring 292x12x21000 mm on mandrels with a diameter of 266/267 mm with a diameter fit of 35.9%. 10 pipes measuring 292x12x10500 mm were accepted according to STP 158-31 and sent to workshop #5 for mechanical processing - boring and turning into round conversion pipes measuring 284.75+2.0/-3.0×6.0+2.0/-1.0 for subsequent processing into hexagonal blank pipes. During preliminary inspection and acceptance, three blanks were rejected due to flaws. 17 blanks were specified for mechanical processing and profiling. During acceptance, two hexagonal blank pipes were rejected due to external films, and two due to internal films, bringing the wall thickness beyond the minus tolerance field. 13 hexagonal blank pipes with a total weight of 2405 kg were conditionally handed over. The metal consumption coefficient during the conversion of ingot-billet ESR - hexagonal pipe-billet for this batch was 3.933. The average steel consumption coefficient during the rolling of ingot-billets with a boron content of 1.3 to 1.8% using the existing technology for 11 months of 2024 was 3.455.

The table shows that the theoretical steel consumption coefficient (the main economic indicator of hexagonal tube production) according to the existing technology was 3.933, according to patent No. 2550033 - 3.955, and according to the proposed technology - 2.635. The theoretical consumption coefficient of 04Kh14T5R2F steel was reduced by using centrifugally cast conversion tube blanks measuring 288x12x5000 mm (the proposed technology), which, relative to patent No. 2530085, was 1320 kg, and relative to the existing technology - 1298 kg for each ton of commercial hexagonal tubes.

Thus, according to the proposed method, in the production of a pilot batch of thin-walled centrifugally cast pipe blanks measuring 288x12x5000 mm from low-ductility steel 04Kh14T5R2F with a boron content of 2.98% for subsequent mechanical processing (boring and turning) into pipe blanks measuring 284.75+2.0/-3.0×6+2.0/-1.0x5000 mm and warm profiling into hexagonal pipe blanks with a spanner size of 257+2.0/-3.0x6.0+2.0/-1.0x4300+80/-20 mm, a reduction in the theoretical metal consumption coefficient relative to patent No. 2530033 by 1320 kg was achieved, and relative to the existing technology - 1298 kg.

The use of the proposed method for the production of conversion centrifugally cast thin-walled tube blanks measuring 288x12.0x5000 mm made of 04Kh14T5R2F steel with a boron content of 2.01 to 3.5% instead of hot-rolled tubes measuring 290x12x5200-5500 mm, rolled on a tube rolling plant with 8-16" pilgrim mills from electroslag remelting ingots measuring 470x100x1650 and 440x100x1750 mm for the manufacture of hexagonal tube blanks with a turnkey size of 257+2.0/-3.0 x6+2.0/-1.0x4300+80/-20 mm for compacted storage in NPP cooling pools and transportation of spent nuclear fuel, will eliminate the need for metal- and energy-intensive technological operations: casting of ESR ingots, heating of ingot blanks in continuous furnaces, piercing of ingot blanks in a cross-helical rolling mill into sleeves and rolling of sleeves on TPU 8-16ʺ with pilgrim mills into hot-rolled pipes measuring 290x12-11000-12000 mm, increasing productivity in the production of hexagonal pipe blanks from CLS of thin-walled pipe blanks measuring 288x12x5000 mm, and, consequently, reducing the cost of commercial hexagonal pipe blanks made of 04X14T5R2F steel.

Claims (1)

A method for producing hexagonal blank pipes with a wrench size of 257+2.0/-3.0x6+2.0/-1.0×4300+80/-20 mm made of low-ductility steel grade 04Kh14T5R2F with a boron content of 2.01 to 3.5% for compacted storage in NPP cooling pools and transportation of spent nuclear fuel, characterized in that thin-walled blank pipes with a size of 288×12×5500 mm are manufactured by centrifugal casting with a diameter tolerance of ±0.5% and a wall thickness of ±5.0%, the end trim is removed to form blank pipes with a size of 288×12×5000 mm, boring and turning are performed on machines with a tracking system into cylindrical blank pipes with a size of 284.75+2.0/-3.0×6+2/-1.0×5000 mm with an average metal removal per side during boring of the inner surface Δ ₁ = 4.5 mm, and during turning of the outer surface Δ ₂ = 1.5 mm, and carry out warm profiling of cylindrical blank pipes into hexagonal blank pipes with a spanner size of 257+2.0/-3.0×6.0+2.0/-1.0×4300+80/-20 mm.