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Manufacturing method for seamless steel tube for large-caliber high-pressure boiler

A technology for high-pressure boilers and seamless steel pipes, which is used in manufacturing tools, metal rolling, metal rolling, etc., can solve the problems of long processing cycle, complex production equipment, large wall thickness unevenness, etc. High geometric accuracy and good product surface quality

Active Publication Date: 2020-01-21
DEXIN STEEL PIPE CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the production equipment of the hot extrusion unit is complicated, the energy consumption is high, the finished product rate is not high, the dimensional accuracy is poor, the wall thickness unevenness is large, and the dimensional accuracy of the inner diameter of the steel pipe cannot be guaranteed
[0005] CN104324972B adopts the periodic pipe rolling unit to roll the pipe and carry out the method of twice push-type thermal expansion to manufacture Φ780×35mm thick-walled seamless steel pipe. Both require annealing heat treatment, resulting in long processing cycle and high energy consumption

Method used

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  • Manufacturing method for seamless steel tube for large-caliber high-pressure boiler
  • Manufacturing method for seamless steel tube for large-caliber high-pressure boiler
  • Manufacturing method for seamless steel tube for large-caliber high-pressure boiler

Examples

Experimental program
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Effect test

Embodiment 1

[0039] In this example, the material of the finished pipe is 10Cr9Mo1VNbN (P91), the outer diameter is 1168.4mm, the nominal wall thickness is 49mm, and the length is greater than 5m. The tolerance is ±10%, the straightness is less than 1.5mm / m, the ellipticity is less than 1.0% of the average diameter, and the performance meets the requirements of GB5310-2017, so the following steps are used for production:

[0040] (1) heating the continuous casting slab with a diameter of 600mm in an annular heating furnace;

[0041] (2) Perforate the heated continuous casting slab with an 820 two-roll cross-rolling piercer, and the outer diameter after the perforation is 790mm;

[0042] (3) Carry out hot-rolled pipe processing with 820 two-roller precision cross-rolling mill, the barren pipe outer diameter that forms after hot-rolling is 813mm, outer diameter deviation ± 1%, nominal wall thickness 54mm, wall thickness deviation ± 10%;

[0043] (4) Straighten and finish the waste pipe so t...

Embodiment 2

[0068] In this embodiment, the material of the finished pipe is 12Cr2MoG (P22), the outer diameter is 1219.2mm, the nominal wall thickness is 28mm, and the length is greater than 6m. The technical agreement requires that the outer diameter tolerance is -3~7mm, the inner diameter tolerance is -2~6mm, and the wall thickness tolerance ±10%, straightness is less than 1.5mm / m, ellipticity is less than 1.0% of the average diameter, the performance meets the requirements of GB5310-2017, and the following steps are used for production:

[0069] (1) heating the continuous casting slab with a diameter of 600mm in an annular heating furnace;

[0070] (2) Perforate the heated continuous casting slab with an 820 two-roll cross-rolling piercer, and the outer diameter after the perforation is 790mm;

[0071] (3) Carry out hot-rolled tube processing with 820 two-roller precision cross-rolling machine, the barren tube outer diameter that forms after hot-rolling is 823mm, outer diameter deviati...

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Abstract

The invention provides a manufacturing method for a seamless steel tube for a large-caliber high-pressure boiler. After an 820 oblique rolling unit is used for perforating, a pierced billet is rolled,an intermediate-frequency heat expanding unit is used for expanding, heat treatment is conducted, and a hydraulic straightener and a six-roller straightener are utilized for two-step straightening and circle tidying. The high-pressure boiler seamless steel tube manufactured through the method can reach following indexes that the outer diameter is 840-1,220 mm, the wall thickness is 25-120 mm, andthe maximum length is 14 mm; and the outer diameter tolerance is + / -1.0%, the inner diameter tolerance is + / -0.75%, the wall thickness tolerance is + / -10%, the straightness is smaller than 1.5 mm / m,and the ovality is smaller than 1.0% of the average diameter.

Description

technical field [0001] The invention relates to a method for manufacturing large-diameter seamless steel pipes, in particular to a method for manufacturing seamless steel pipes for high-pressure boilers with a diameter of 840-1220 mm. Background technique [0002] my country is rich in coal resources, and thermal power generation is the main way of power supply in my country. In order to achieve the purpose of energy saving, environmental protection and thermal efficiency improvement, thermal power generating units continue to develop towards high parameters and large-scale, 600MW and 1000MW ultra-supercritical generating units have become the mainstream of development, and the large-scale development of generating units requires the use of a large number of large-caliber high-voltage Seamless boiler tubes. Especially in order to achieve the flow cross-sectional area and design flow required by the design, the size of the inner diameter of the seamless steel pipe is also re...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B21B19/04B21B15/00B21D39/20B21D37/18B21D37/16B21B38/00
CPCB21B15/00B21B19/04B21B38/00B21B2038/004B21D37/16B21D37/18B21D39/20
Inventor 王洪海陈俊德陈冬桑伟王本军董西岳
Owner DEXIN STEEL PIPE CHINA
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