RU2542150C2 - PRODUCTION OF SEAMLESS COLD-RESISTANT AND NONCORROSIVE 377×9-16 AND 426×9-18 mm PIPES AT PRU 8-16 WITH PILGER MILLS WITH STRINGENT REQUIREMENTS TO CURVATURE - Google Patents

Abstract

FIELD: process engineering.

SUBSTANCE: invention relates to pipe rolling. Conical billets are cast with shrink head of 540/555x1650 mm as well as continuously cast billets of 550x1750-2100 mm. Through central 100±5 mm diameter bore is drilled therein. Sleeves are heated to ductility temperature. Ingots sized to 540/555×100×1650 mm are pierced to 560×ID390×2870 mm sleeves with diameter increase over ingot length of 0.9-3.7% and continuously cast 550×100×1750-1850 m to sleeves sized to 550×ID390×3300-3500 in OD. Pipe lengths are rolled at Pilger mill 390 mm roll-pass with pipe turn-over through 70±2°. Pipe are cut to gaged lengths and process wastes are remove to heat said lengths in gas roll furnace to 880-900°C. Pipes are gaged at sizing mill with total diameter decrease of up to 1.8% and straightened at oblique roll machine.

EFFECT: decreased metal consumption factor.

2 cl, 1 tbl

Description

The invention relates to pipe production, and in particular to a method for the production of hot-rolled seamless cold-resistant and corrosion-resistant pipes with a size of 377 × 9-16 mm with increased requirements for curvature, and can be used on an 8-16 ″ pipe-rolling installation with pilgrim mills of ChTPZ OJSC "having a cross-helical rolling mill and a five-stand calibration mill.

In the practice of pipe production, there are methods for rolling seamless hot-formed cold-resistant and corrosion-resistant pipes of large and medium diameters from steel 20FA, 13KhFA, 09GSF, 06Kh1 NFA and 08KhMFBCHA, designed for the construction and operation of oil pipelines in the northern climatic zone, oil producing enterprises of Western Siberia, the Republic Komi, Kazakhstan and Orenburg, at an ambient temperature from minus 60 ° to plus 50 ° with a temperature of transported media from minus 20 ° to plus 60 °, which have a higher stability of mechanical characteristics, low temperature of viscous-brittle transition, increased resistance to general and ulcerative corrosion, resistance to sulfide corrosion cracking and the formation of hydrogen cracks, including ingot casting, baking process, ingot repair and baking process (if necessary), forging, forging, machining forgings into billets, drilling of a central hole with a diameter of 100 ± 5 mm, heating ingots, NLZ and forged billets to a ductility temperature (1270-1300) ° С, flashing them in the mill end screw rolling into sleeves, rolling sleeves on a pilgrim mill to pipes with a diameter of 273, 299, 325, 351, 377 and 426 mm with wall thicknesses from 8 to 16 mm, cutting pipes into measured lengths, removing process waste (seed ends and pilgrim heads) of hot cutting with circular saws, heating of pipes (normalization) in a gas-fired furnace, calibration of pipes in a calibration mill with a total compression of up to 1.0% in diameter, straightening on a straighting machine, electromagnetic control, preliminary marking of pipes, initial quality control surfaces, edge trimming, preliminary acceptance, ultrasonic inspection of repaired pipes, normalization of pipes in a sectional furnace, straightening of pipes on a straighting machine, heat treatment of pipes (hardening and tempering) in induction plants, sampling for acceptance and corrosion tests, pipe quality control, pipe straightening, if necessary, pre-tempering of pipes that have been straightened, chamfering, receiving, marking and weighing pipes, preparing final acceptance lists and shipping pipes to the customer (TU 14-158- 125-2001 "Seamless hot-deformed oil and gas pipes with increased service life with a diameter of 273-426 mm", TU 14-158-114-99 "Seamless hot-deformed oil and gas pipes with increased cold resistance and corrosion resistance", TU 14-158-112-99 "Seamless pipes hot-deformed oil and gas pipelines of increased cold and corrosion resistance for fields of OJSC "Surgutneftegas", TI 158-Tr. TB1-91-2009 "Production of seamless hot-deformed pipes from ingots according to TU 14-158-112-99, TU 14-158-114-99, TU 14-158-125-2001 ", TU 14-1308-245-01470016-2002" Tr seamless steel hot-deformed oil and gas pipelines with increased durability, designed for use in corrosive environments ", TU 137-233-0147016-2002" Seamless hot-deformed oil and gas pipelines with a diameter of 273-426 increased reliability during operation for the fields of OAO Tomskneft VNK, TU 1308-226-0147016-2002 "Seamless hot-deformed oil and gas pipeline pipes from microalloyed steels with increased service life", TU 1317-214-0147016-2002 "Hot-deformed seamless pipe oil and gas industry ovodic diameters of 273-426 increased operational reliability for the fields of TPP Kogalymneftegaz, TI 158-Tr. TB1-27-2008 "Production of seamless hot-deformed oil and gas pipelines with a diameter of 273-426 mm according to TU 1317-214-0147016-2002, TU 1308- 226-0147016-2002, TU 137-233-0147016-2002, TU 1308-226-0147016-2002 ").

The disadvantages of these methods is the increased expenditure coefficient of the metal (1,485-1,529) during the redistribution of the ingot pipe due to rejection and transfer of a large number of pipes to lower quality according to the outer and inner captures (rolled defects due to low-quality metal) and local curvature per meter pipes along the length and perimeter exceeding 1.5 mm (rolled defect), most of which are detected after quenching and tempering, i.e. at the final acceptance, which, in turn, leads to a rise in the cost of finished products and a decrease in its profitability.

In pipe production, methods for flashing ingots (billets) to rise from 3.0 to 7.0%, size to size and fit (compression) from 2.0 to 5.0% are known, where, with a change in the stress-strain state diagram, deformation expressed by the amount of drawing (F.A. Danilov et al. Hot rolling of pipes, Moscow, Metallurgizdat, 1962, p. 297).

The disadvantage of these methods of firmware is the impossibility of obtaining high-quality (without the presence of internal and external captivity) sleeves from open-hearth ingots. In the rolling table for TI 158Tr.TB1-91-2009, pipes with a diameter of 377 mm are rolled from profitable drilled ingots of 540/555 × 100 × 1650 mm in size. The profitable part is cut by fire cutting at a length of 200-300 mm. The outer diameter of the sleeve after flashing 560 mm with an average ingot diameter of 547.5 mm, i.e. the firmware process is performed with a rise along the length of the ingots from 0.9 to 3.7%.

The closest technical solution is a method for the production of pipes of large and medium diameters from cold-resistant and corrosion-resistant steel grades in pipe rolling plants with pilgrim mills, including rolling pipes from cold-resistant and corrosion-resistant steel grades from continuously cast billets with a diameter of 430 mm without central hole drilling , NLZ firmware in a cross-screw rolling mill with a hood of 1.5-1.6, pipe rolling on pilgrim mills with a hood of µ from 7.5 to 15, large values of which relate to dia pipes with a diameter of 273 mm, and smaller to pipes with a diameter of 426 mm, rolling pipes with a diameter of 273 and 299 mm on a pilgrim mill from sleeves stitched in a cross-screw mill with a rise in diameter of 4.5-5.0%, pipes with a diameter of 325 and 351 mm from sleeves stitched with a rise in diameter of 15-20%, and pipes with a diameter of 377 and 426 mm from sleeves stitched with a rise in diameter of 21-30%, heating NLZ for piercing for rolling pipes with a diameter of 273 and 299 mm to a temperature of 1250- 1270 ° C, for rolling pipes with a diameter of 325 and 351 mm - to a temperature of 1250-1270 ° C, and for rolling pipes with a diameter of 377 and 426 mm - to a temperature of 1270-1290 ° C, rolling pipes with a diameter of 273 and 299 mm three times the length, and pipes with a diameter of 325, 351, 377 and 426 mm double the length, flashing NLZ in sleeves with a rise in diameter of 4.5-5.0% and with a speed of rotation of the work rolls 44-40 rev / min, with a rise in diameter of 15-20% - with a speed of rotation of the work rolls 40-38 rpm, and with a rise in diameter of 21-30% - with a speed of rotation of the work rolls 38-36 r / min (RF Patent No. 2306992 from 09/29/2007, class B21B 21/00, B21B 21/04, bull. No. 27).

The disadvantage of this method is that this method does not solve the main issue, namely the production of pipes of these sizes with increased requirements for curvature. In 2005, in Russia and world practice, there were continuous steel casting plants for the production of billets with a diameter of up to 430 mm, which, according to economic, technological and quality indicators, are the most optimal for the production of pipes with a diameter of 273 and 299 mm. Firmware NLZ with a diameter of 430 mm in sleeves with a rise in diameter from 15 to 30% and an extraction coefficient µ close to 1.0 is impractical, because leads to extreme tangential tensile stresses, which, in turn, leads to increased curvature of the sleeves and the formation of defects in the form of external and internal captures. Rolling the sleeves with increased curvature on the pilgrim mills leads to the difficulty of introducing the mandrel into the sleeve, reducing the performance of the pilgrim installations, the increased lateral difference of the pipes and, as a result, the transfer of these pipes to lower quality or to the final marriage and increased metal consumption.

The objective of the proposed method (invention) is the development and implementation of a technology for the production of seamless cold-resistant and corrosion-resistant pipes with a size of 377 × 9-16 mm in tube rolling plants with pilgrim mills with increased local requirements for curvature per linear meter along the length and perimeter that satisfy customer requirements , reduction in metal consumption by reducing the local curvature by one linear meter (defect of rolling origin) when rolling pipes of size 377 × 9-16 mm from cold-resistant and corrosion-resistant Toyko steels.

, где ω=1,05 - среднее значение коэффициента опережения течения металла на полирующем участке пилигримовых валков; R_o - радиус валка по вершине калибра на полирующем участке, мм; Θ_n=1,22 - центральный угол полирующего участка пилигримового валка, радианы; k=2,75 - коэффициент полировки при прокатке труб; µ_i - коэффициент вытяжки при прокатке труб i-го размера, который определяют из выражения: $${\mu }_i=\frac{(D_{г}-S_{г})S_{г}}{(D_m-S_m)S_m}$$

, где D_г - наружный диаметр гильзы, мм; S_ш - толщина стенки гильзы, мм; D_m - наружный диаметр горячекатаной трубы после пилигримового стана, мм; S_m - толщина стенки горячекатаной трубы, мм.The technical result is achieved by the fact that in the known method for the production of seamless cold-resistant and corrosion-resistant pipes with a size of 377 × 9-16 mm on TPU 8-16 ″ with pilgrim mills with increased curvature requirements, including casting cone ingots with a profit size of 540/555 × 1650 mm and continuously cast billets (NLZ) of size 550 × 1750-2100 mm, drilling in ingots and NLZ of a central hole with a diameter of 100 ± 5 mm, heating them to plasticity temperature, piercing 540/555 ingots in cross-helical rolling mill × 100 × 1650 mm in sleeve sizes m 560 × in. 390 × 2870 mm with a rise in diameter along the length of the ingots from 0.9 to 3.7%, continuously cast billets of size 550 × 100 × 1750-1850 mm in sleeves of size 550 × in. 390 × 3300-3500 mm size to outer diameter, rolling of lash tubes on pilgrim mills in caliber 390 mm with tilting of sleeve tubes at an angle of 70 ± 2 °, cutting into measured lengths, removal of process waste - seed ends and pilgrim heads with a hot cutting saw, heating in a gas roller furnace to a temperature of 880-900 ° C, calibration of pipes in a calibration mill with a total diameter reduction of up to 1.8%, right on a Kosovalkovy straightening machine, electromagnetic control, preliminary marking of pipes, initial control of surface quality, trimming, preliminary acceptance, ultrasonic control of repaired pipes, normalization of pipes in a sectional furnace, straightening of pipes on a Kosovalkovy straightening machine, quenching and tempering at induction plants, selection samples for acceptance and corrosion tests, pipe quality control, pipe straightening, chamfering, acceptance, marking and weighing of pipes, while the pipes are on a pilgrim the mill is rolled with outer diameters, the values of which are determined from the expression: _cf. D _mi = _nom. D _m. γ + 2S _i (δ _max -δ _min ), where _nom. D _m. - nominal diameter of commodity pipes, mm; γ is the coefficient of linear expansion of steel at a rolling temperature of ≈1000 ° C; S _i - the thickness of the stacks of the rolled pipe, mm; δ _min - minus the field of tolerance of the pipes on the wall, the pipes are rolled on a pilgrim mill with feeds, the values of which are determined from the expression: $$m_{\max }\le \frac{\omega R_o{\Theta }_n}{k{\mu }_i}$$

where ω = 1.05 is the average value of the coefficient of advance of the metal flow in the polishing section of the pilgrim rolls; R _o is the radius of the roll at the top of the caliber in the polishing section, mm; Θ _n = 1.22 is the central angle of the polishing section of the pilgrim roll, radians; k = 2.75 - polishing coefficient during pipe rolling; µ _i is the drawing coefficient when rolling pipes of the i-th size, which is determined from the expression: $${\mu }_i=\frac{(D_g-S_g)S_g}{(D_m-S_m)S_m}$$

where D _g is the outer diameter of the sleeve, mm; S _W - wall thickness of the sleeve, mm; D _m - the outer diameter of the hot-rolled pipe after the pilgrim mill, mm; S _m - wall thickness of the hot-rolled pipe, mm

, где ω=1,05 - среднее значение коэффициента опережения течения металла на полирующем участке пилигримовых валков; R_o - радиус валка по вершине калибра на полирующем участке, мм; Θ_n=1,22 - центральный угол полирующего участка пилигримового валка, радианы; k=2,75 - коэффициент полировки при прокатке труб; µ_i - коэффициент вытяжки при прокатке труб i-го размера, который определяют из выражения: $${\mu }_i=\frac{(D_{г}-S_{г})S_{г}}{(D_m-S_m)S_m}$$

, где D_г - наружный диаметр гильзы, мм; S_г - толщина стенки гильзы, мм; D_m - наружный диаметр горячекатаной трубы после пилигримового стана, мм; S_m - толщина стенки горячекатаной трубы, мм. Эти отличия позволяют сделать вывод о соответствии критерию "изобретательский уровень".Comparative analysis with the prototype shows that the inventive method for the production of seamless cold-resistant and corrosion-resistant pipes with a size of 377 × 9-16 mm on TPU 8-16 ″ with pilgrim mills with increased requirements for curvature differs in that the pipes are rolled onto pipes on the pilgrim mill with outer diameters, the values of which are determined from the expression: _cf. D _mi = _nom. D _m. γ + 2S _i (δ _max -δ _min ), where _nom. D _m - nominal diameter of commodity pipes, mm; γ — coefficient of linear expansion of steel at rolling temperature ≈1000 ° С; S _i - the thickness of the stacks of the rolled pipe, mm; δ _max - plus field tolerance of pipes along the wall; δ _min - minus the field of tolerance of the pipes on the wall, the pipes are rolled on a pilgrim mill with feeds, the values of which are determined from the expression: $$m_{\max }\le \frac{\omega R_o{\Theta }_n}{k{\mu }_i}$$

where ω = 1.05 is the average value of the coefficient of advance of the metal flow in the polishing section of the pilgrim rolls; R _o is the radius of the roll at the top of the caliber in the polishing section, mm; Θ _n = 1.22 is the central angle of the polishing section of the pilgrim roll, radians; k = 2.75 - polishing coefficient during pipe rolling; µ _i is the drawing coefficient when rolling pipes of the i-th size, which is determined from the expression: $${\mu }_i=\frac{(D_g-S_g)S_g}{(D_m-S_m)S_m}$$

where D _g is the outer diameter of the sleeve, mm; S _g - wall thickness of the sleeve, mm; D _m - the outer diameter of the hot-rolled pipe after the pilgrim mill, mm; S _m - wall thickness of the hot-rolled pipe, mm These differences allow us to conclude that the criterion of "inventive step".

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 solution from the prototype, which corresponds to the patentability "inventive step".

Due to the tolerances on the wall of +12.5 minus 15%, the thickness difference for pipes with a size of 377 × 9-16 mm varies from 2.48 to 4.4 mm. This difference (tuberosity) can lead to a difference in diameters along the length of the lash tubes after the pilgrim mill, respectively, from 4.96 to 8.8 mm. In order for the local curvature per linear meter along the length and perimeter of the commodity pipes not to exceed (h≤1.5 mm), it is necessary to calibrate the pipes with compression in diameter from 4.96 to 8.8 mm, respectively. To unify the calibrations of the pilgrim mill rolls, it is proposed to use average reductions for pipes with a diameter of 377 mm Δ _{cf. 377} = (4.96 + 8.8) / 2 = 6.88 mm. The use of this method of rolling hot-rolled pipes at TPU 8-16 ″, followed by heating them in a continuous gas roller furnace to a temperature of 880-900 ° C, depending on the geometric dimensions, gives the basis for rolling commodity pipes of 377 × 9-16 mm metal consumption by reducing rejection and transferring pipes to a lower quality (not having strict requirements for local curvature) and to increase the productivity of TPU 8-16 ″. An increase in the outer diameter of hot-rolled pipes by 6–7 mm makes it possible to increase the diameter reduction in the calibration mill to 1.80 and 2.05%, respectively, instead of 1.0%, according to existing technology, which makes it possible to reduce the local (local) pipe curvature from - due to irregularity of supply or its excess (due to tuberosity). Rolling pipes with a size of (388-389) × 9-16 mm with a sleeve of pipe sleeves at an angle of 70 ± 2 ° will increase the polishing coefficient and, therefore, reduce the lateral difference (thickness difference), and rolling pipes with theoretically justified feeds will reduce the longitudinal difference .

Thus, the use of the proposed method will make it possible to produce pipes with a size of 377 × 9-16 mm from cold-resistant and corrosion-resistant steel grades on TPU 8-16 ″ with piligrim mills with increased local curvature requirements, reduce metal consumption, increase TPU 8 productivity -16 ″ with pilgrim mills, increase their production and meet the needs of customers in the pipes of this assortment.

The method of producing pipes from cold-resistant and corrosion-resistant steel of 20FA grade according to the existing and proposed technologies was tested when rolling pipes of 377x9 mm in size on TPU 8-16 ′ ′ with pilgrim mills of ChTPZ OJSC from profitable open-hearth bars of ChTPZ OJSC. Data on the rolling and commissioning of cold-resistant and corrosion-resistant pipes 377 × 9 mm in size, rolled on TPU 8-16 ′ ′ with pilgrim mills from profitable ingots with a diameter of 15 and NLZ with a diameter of 550 mm from steel of 20FA grade supplied by OAO ChTPZ according to the existing and proposed technologies are shown in the table. The table shows that according to the existing technology for rolling pipes of size 377 × 9 mm, drilled profitable ingots of 540/555 × 100 × 1900 mm or NLZ with dimensions of 550 × 1750-1850 mm are used. The shrink part 250 mm high was removed from the ingots by fire, then the ingots were drilled to a diameter of 100 ± 5 mm. The ingots were received by UTK and heated in a methodical furnace to a temperature of 1280-1300 ° C, were stitched in a cross-helical rolling mill into sleeves measuring 560 × ext. 390 × 2870 mm with an increase in diameter along the length of the ingot from 0.9 to 3.7% and hood µ _CR = 1/74. The average diameter rise of the liners is 2.28%. On the outer and inner surfaces of the liners, captives were observed. The sleeves were fed to a pilgrim mill and rolled in caliber 383 mm in diameter into triple length pipes with a sleeve of pipe sleeves at an angle of 90 ± 10 °, with a drawing coefficient µ _n = 12.04 and feeding the sleeves into the deformation zone m = 15-17 mm. The hot diameter of the pipes after the pilgrim mill was 381-382 mm. Then the pipes were heated in a gas roller furnace to a temperature of 800-840 ° C and calibrated in a five-stand calibration mill with a diameter reduction of up to 1.0%. 75 ingots with a total weight of 206.6 tons were commissioned. Accepted pipes according to TU 136.3 tons. The expenditure coefficient of the metal was 1.516. The average length of the pipe at delivery was 7.42 m. The pipes were rejected for defects of metallurgical origin (external and internal films, hairline) and for local curvature exceeding 1.0 mm per meter of length. Pipes required repair to remove defects before and after ultrasonic testing. According to the proposed technology, 73 profitable ingots of 540 × 555 × 100 × 1650 mm in size with a total weight of 206.6 tons were set into production. The ingots were drilled to a diameter of 100 ± 5 mm, received by CTF and heated in a methodical furnace to a temperature of 1280-1300 ° C, were stitched in a cross-helical rolling mill into sleeves measuring 560 × ext. 390 × 2870 mm with an increase in diameter along the length of the ingot from 0.9 to 3.7% and a hood µ _ol = 1.74. The average diameter rise of the liners is 2.28%. On the outer and inner surfaces of the liners, captives were observed. The sleeves were fed to the pilgrim mill and rolled in caliber with a diameter of 390 mm into tubes of three lengths with a sleeve of pipe sleeves at an angle of 70 ± 2 ° with a draw ratio µ _n = 12.4 and feeding the sleeves into the deformation zone m = 12-13 mm. The hot diameter of the pipes after the pilgrim mill was 388-389 mm. The pipes were heated in a gas roller furnace to a temperature of 880-900 ° C and calibrated in a five-stand calibration mill with a diameter reduction of up to 1.8%. Accepted pipes according to TU 110.8 tons. Pipes were rejected for defects of metallurgical origin (outer and inner captives, hairline). There was no marriage of local curvature exceeding 1.0 mm per meter of length. Pipes required repair to remove defects before and after ultrasonic testing. The expenditure coefficient of the metal in the pipes of this batch was 1.295 or 0.221 less than with the existing technology, i.e. metal consumption decreased by 221 kg per ton of pipe. The average pipe length at delivery amounted to 8.07 m, i.e. increased by 17.3%. On the pipes, due to the presence of external captures and hairs, defective places were cut out. Pipes required repair to remove defects before and after ultrasonic testing. There was no marriage and the conversion of pipes to lower quality according to local curvature.

A similar picture was obtained when rolling pipes of size 377 × 9 mm from NLZ. According to existing technology for rolling pipes with a size of 377 × 9 mm, drilled NLZ with a size of 550 × 1800 mm are used. The billets were taken by UTK and heated in a methodical furnace to a temperature of 1280-1300 ° C, were stitched in a cross-helical mill in sleeves measuring 550 × in. 390 × 3400 mm in size in diameter with an extract µ _pr = 1.89. On the outer surfaces of the liners were observed captivity. The sleeves were fed to the pilgrim mill and rolled in caliber 383 mm in diameter into tubes of three lengths with a sleeve of pipe sleeves at an angle of 90 ± 10 °, with a drawing coefficient µ _n = 11.22 and feeding the sleeves into the deformation zone m = 15-17 mm. The hot diameter of the pipes after the pilgrim mill was 381-382 mm. Then the pipes were heated in a gas roller furnace to a temperature of 800-840 ° C and calibrated in a five-stand calibration mill with a diameter reduction of up to 1.0%. 57 blanks with a total weight of 192.5 tons were set into production. Accepted pipes according to TU 130.9 tons. The expenditure coefficient of the metal was 1,471. The average pipe length at delivery was 9.38 m. Pipes were rejected for defects of metallurgical origin (outer films and hairline) and for local curvature exceeding 1.0 mm per meter of length. Pipes required repair to remove defects before and after ultrasonic testing. According to the proposed technology, 49 NLZ with a size of 550 × 1800 mm with a total weight of 162.8 tons were assigned to production. The billets were drilled to a diameter of 100 ± 5 mm, received by the UTC and heated in a methodical furnace to a temperature of 1280-1300 ° C, were stitched in a cross-screw mill in sleeves measuring 550 × in. 390 × 3400 mm in size in diameter and by hood µ _ol = 1.89. On the outer surfaces of the liners were observed captivity. The sleeves were fed to the pilgrim mill and rolled in caliber with a diameter of 390 mm into tubes of three lengths with a sleeve of pipe sleeves at an angle of 70 ± 2 ° with a draw ratio µ _n = 11.22 and feeding the sleeves into the deformation zone m = 12-13 mm. The hot diameter of the pipes after the pilgrim mill was 388-389 mm. The pipes were heated in a gas roller furnace to a temperature of 880-900 ° C and calibrated in a five-stand calibration mill with a diameter reduction of up to 1.8%. Accepted pipes according to TU 125.1 tons. Pipes were rejected for defects of metallurgical origin (external captives and hairline). There was no marriage of local curvature exceeding 1.0 mm per meter of length. Pipes required repair to remove defects before and after ultrasonic testing. The expenditure coefficient of the metal in the pipes of this batch was 1.309 or 0.171 less than with the existing technology, i.e. metal consumption decreased by 171 kg per ton of pipe. The average pipe length at delivery amounted to 10.42 m, i.e. increased by 11.1%. On the pipes, due to the presence of external captures and hairs, defective places were cut out. Pipes required repair to remove defects before and after ultrasonic testing. There was no marriage and the conversion of pipes to lower quality according to local curvature.

Thus, the use of the proposed method for the production of seamless cold-resistant and corrosion-resistant pipes with a size of 377 × 9-16 mm on pipe rolling plants with pilgrim mills will reduce the expenditure coefficient of the metal (the main economic indicator in the production of pipes) by reducing rejection and transferring pipes to lower quality according to local curvature by one linear meter, to increase the length of commodity pipes, which, in turn, makes it possible to reduce the number of mounting joints during construction and operation eprovodov in a northern climate zone, to reduce the redistribution of costs and increase the profitability of the production of pipes of the mix.

Claims (2)

1. Method for the production of seamless cold-resistant and corrosion-resistant pipes of size 377 × 9-16 on TPU 8-16 "with pilgrim mills with increased requirements for curvature, including casting cone ingots with a profit size of 540/555 × 1650 mm and continuously cast billets (NLZ) with a size of 550 × 1750-2100 mm, drilling in ingots and NLZ of a central hole with a diameter of 100 ± 5 mm, heating them to a plasticity temperature, piercing 540/555 × 100 × 1650 mm in size in sleeves of cross-helical rolling of ingots 560 × ext. 390 × 2870 mm with a rise in diameter along the length of the ingots from 0.9 to 3 , 7%, continuously cast billets of size 550 × 100 × 1750-1850 mm in sleeves of size 550 × ext. 390 × 3300-3500 mm; size in outer diameter; rolling of lashing tubes on pilgrim mills in caliber 390 mm with a pitch sleeve tubes at an angle of 70 ± 2 °, cutting into measured lengths, removing technological waste - seed ends and pilgrim heads with a hot cutting saw, heating in a gas roller furnace to a temperature of 880-900 ° C, calibrating the pipes in a calibration mill with a total compression of diameter up to 1.8%, straightening on a Kosovalkovy straightening machine, electromagnetic contact nol, preliminary marking of pipes, initial quality control of the surface, trimming of the ends, preliminary acceptance, ultrasonic control of repaired pipes, normalization of pipes in a sectional furnace, straightening of pipes on a straighting machine, hardening and tempering at induction plants, sampling for acceptance and corrosion tests, pipe quality control, pipe straightening, chamfering, pipe receiving, marking and weighing, while pipes on a pilgrim mill are rolled with external diameters, the values of which predelyayut from the expression:
_Wed D _mi = _nom. D _m. γ + 2S _i (δ _max -δ _min ),
where _number D _m - nominal diameter of commodity pipes, mm;
γ — coefficient of linear expansion of steel at rolling temperature ≈1000 ° С;
S _i - the thickness of the stacks of the rolled pipe, mm;
δ _max - plus field tolerance of pipes along the wall;
δ _min - minus the field tolerance of the pipes on the wall. 2. The method according to claim 1, characterized in that the pipes are rolled on a pilgrim mill with feeds, the values of which are determined from the expression:
$$m_{\max }\le \frac{\omega R_o{\Theta }_n}{k{\mu }_i}$$

,
where ω = 1.05 - the average value of the coefficient of advance of the metal flow on the polishing section of the pilgrim rolls;
R _o is the radius of the roll at the top of the caliber in the polishing section, mm;
Θ _n = 1.22 is the central angle of the polishing section of the pilgrim roll, radians;
k = 2.75 - polishing coefficient during pipe rolling;
µ _i - drawing coefficient when rolling pipes of the i-th size, which is determined from the expression
$${\mu }_i=\frac{(D_g-S_g)S_g}{(D_m-S_m)S_m}$$

,
where D _g is the outer diameter of the sleeve, mm;
S _g - wall thickness of the sleeve, mm;
D _m - the outer diameter of the hot-rolled pipe after the pilgrim mill, mm;
S _m - wall thickness of the hot-rolled pipe, mm