超临界CO2输送用L450M钢级HFW焊管开发
黄晓辉1,2毕宗岳1,2赵西岐1,2张锦刚1,2韦奉1,2王博玉1,2詹文文1,2

1.中油国家石油天然气管材工程技术研究中心有限公司;2.宝鸡石油钢管有限责任公司

超临界CO2;L450钢;X65钢;焊管;韧脆转变温度

Development of L450M HFW pipes for supercritical CO2 transmission
HUANG Xiaohui1,2,BI Zongyue1,2,ZHAO Xiqi1,2,ZHANG Jingang1,2,WEI Feng1,2,WANG Boyu1,2,ZHAN Wenwen1,2

1.Chinese National Engineering Research Center for Petroleum and Natural Gas Tubular Goods Co. Ltd.; 2.Baoji Petroleum Steel Pipe Co. Ltd.

supercritical CO2, L450 steel, X65 steel, welded pipe, ductile-brittle transition temperature

DOI: 10.6047/j.issn.1000-8241.2024.05.008

备注

【目的】随着“双碳”目标的推进,超临界CO2输送管道用钢朝着更高钢级方向发展。【方法】采用低C、中Mn、微Ni合金化设计、高洁净化炼钢及大吨位压下轧制技术,开发出微观组织以细小扁平的多边形铁素体+铁素体+少量珠光体为主的L450M钢级(X65钢级)超临界CO2输送管用热轧卷板。针对设计压力16MPa的超临界输送用OD219.1mm×10mm(管径×壁厚)高频焊接(High Frequency Welding, HFW)焊管,为保证该HFW焊管运行时具有抗起裂与抗断裂扩展能力,经过计算,要求-45℃下母材夏比冲击吸收能量单值不小于88J、均值不小于117J,-45℃下焊缝、热影响区夏比冲击吸收能量单值不小于42J、均值不小于56J。【结果】经成型、焊接及热处理工艺研究,在成型挤压量5.25mm,焊接速度17m/min,焊缝热处理温度930℃工艺下,开发出低温性能优异的L450M钢级超临界CO2输送用HFW焊管。经第三方检测,该焊管性能完全符合APISpec5L《管线钢管》(46版)标准与低温韧性要求,经压扁试验压至贴合,母材与焊缝均未出现任何裂纹,表明母材与焊缝具有很强的塑性,焊缝质量优异。母材屈服强度534MPa,母材、焊缝的抗拉强度基本一致,分别为619MPa、620MPa,均达到不低于535MPa的标准要求,强度裕量大。母材、焊缝及热影响区的硬度均不高于220HV10且分布均匀。-45℃下焊缝冲击吸收能量为177~401J、热影响区冲击吸收能量为200~415J、母材冲击吸收能量为248~416J,且母材、焊缝、热影响区的韧脆转变温度均低于-60℃。【结论】该HFW焊管低温韧性优异,抗低温延性止裂能力高,且承受最大内压与外压能力分别达到62.29MPa、38.9MPa,完全满足超临界CO2输送用HFW焊管的运行需求。(图 10表3,参[25]
[Objective] This study aims at fulfilling the steel requirements for supercritical CO2 transmission. [Methods] L450M (X65) hot rolled coils for pipes used in supercritical CO2 transmission were developed, with a microstructure mainly consisting of fine and flat polygonal ferrite + ferrite + a small amount of pearlite, boasting a Low-C medium-Mn micro-Ni alloying design, and leveraging the high-purification steelmaking and large-tonnage reduction rolling technologies. Numerous calculations were performed, focusing on OD219.1 mm×10 mm (pipe diameter×wall thickness) High Frequency Welding (HFW) pipes for supercritical transmission with a design pressure of 16 MPa, to ensure their resistance to cracking initiation and fracture propagation during operation, yielding the following results. The Charpy impact absorbed energy in the base metal at -45 ℃ was not less than 88 J for single values or not less than 117 J for averages. The Charpy impact absorbed energy in the welds and heat-affected zones at -45 ℃ was not less than 42 J for single values or not less than 56 J for averages. [Results] Based on the initial investigation into the forming, welding, and heat treatment processes, L450M HFW pipes for supercritical transmission with excellent cryogenic properties were developed under the following conditions: forming extrusion of 5.25 mm, welding rate at 17 m/min, and weld heat treatment at 930 ℃. The third-party testing validated the performance of the developed welded pipes in full compliance with the Line Pipe (API Spec 5L, 46th edition), and cryogenic toughness requirement. During the flattening experiment, the flattened pipes showcased no cracks within the base metal and welds. This observation underscored the robust plasticity and exceptional weld quality of both the base metal and welds. The yield strength of the base metal was 534 MPa, and the tensile strengths of the base metal and welds closely matched at 619 MPa and 620 MPa respectively, meeting the standard requirement of not less than 535 MPa and suggesting a sufficient strength margin. The hardness levels of the base metal, welds, and heat-affected zones did not surpass 220 HV10 and exhibited uniform profiles. At -45 ℃, the impact absorbed energy ranged from 177 J to 401 J for welds, from 200 J to 415 J for the heat-affected zones, and from 248 J to 416 J for the base metal. Furthermore, the ductile-brittle transition temperatures of the base metal, welds, and heat-affected zones remained below -60 ℃. [Conclusion] The developed HFW pipes demonstrate exceptional cryogenic toughness, high ductile crack arrest capabilities still under low temperatures, and impressive internal and external pressure-bearing capacities of 62.29 MPa and 38.9 MPa respectively. These properties are fully aligned with the operational requirements for HFW pipes utilized in supercritical CO2 transmission. (10 Figures, 3 Tables, 25 References)
·