Effect of casting process on the inner-wall band segregation of high-strength antisulfur pipes

Controlling inner-wall band segregation is one of the difficulties in the production of high-strength antisulfur pipes.Comparative tests were carried out on different casting processes(superheat,mold electromagnetic stirring,end electromagnetic stirring,casting speed and soft reduction)for the smelting of high-strength antisulfur pipes.The microstructures of continuous-casting billets and hot-rolled or tempered pipes were analyzed using a metallographic microscope and scanning electron microscope.The mechanism and evolution law regarding the inner-wall band segregation of high-strength antisulfur pipes were studied,and the influence of different casting processes was explored.

High-Gain Array Antenna Based on Composite Right/Left-Handed Transmission Line

In this paper a metamaterial-inspired antenna with high gain and good directivity is designed. Based on the concept of composite right/left-handed transmission line (CRLH-TL), the proposed antenna is realized based on three leakage wave unit cell and a left handed circular ring slot incorporated on the surface. The maximum achievable gain at the resonant frequency of 5.6GHz is 6.933 dBi, and the return loss at 5.6 GHz can be –20 db. This proposed design has a simple structure and a compact dimension of 35 mm*40 mm*1 mm, which is suitable for particular wireless communication application such as WiFi and WLAN.

Effect of microstructure on the low temperature toughness of high strength pipeline steels

Microstructure observations and drop-weight tear test were performed to study the microstructures and mechanical properties of two kinds of industrial X70 and two kinds of industrial X80 grade pipeline steels. The effective grain size and the fraction of high angle grain boundaries in the pipeline steels were investigated by electron backscatter diffraction analysis. It is found that the low temperature toughness of the pipeline steels depends not only on the effective grain size, but also on other microstructural factors such as martensite-austenite （MA） constituents and precipitates. The morphology and size of MA constituents significantly affect the mechanical properties of the pipeline steels. Nubby MA constituents with large size have significant negative effects on the toughness, while smaller granular MA constituents have less harmful effects. Similarly, larger Ti-rich nitrides with sharp corners have a strongly negative effect on the toughness, while fine, spherical Nb-rich carbides have a less deleterious effect. The low temperature toughness of the steels is independent of the fraction of high angle grain boundaries.

Application of high temperature heat pipe in hypersonic vehicles thermal protection

In order to develop further the application of high temperature heat pipe in hypersonic vehicles thermal protection, the principles and characteristics of high temperature heat pipe used in hypersonic vehicles thermal protection were introduced. The methods of numerical simulation, theory analysis and experiment research were utilized to analyze the frozen start-up and steady state characteristic of the heat pipe as well as the machining improvement for fabricating irregularly shaped heat pipe which is suitable for leading edge of hypersonic vehicles. The results indicate that the frozen start-up time of heat pipe is long （10 min） and there exists large temperature difference along the heat pipe （47 ℃/cm）, but the heat pipe can reduce the temperature in stagnation area of hypersonic vehicles from 1 926 to 982 ℃ and work normally during 1 000-1 200℃. How to improve the maximum heat transfer capability and reduce the time needed for start-up from frozen state of the heat pipe by optimizing thermostructure such as designing of a novel wick with high performance is the key point in hypersonic vehicles thermal protection of heat pipe.

Maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick

A mathematical model was developed to predict the maximum heat transfer capacity of high temperature heat pipe with triangular grooved wick. The effects of the inclination angle and geometry structure were considered in the proposed model.Maximum heat transfer capacity was also investigated experimentally. The model was validated by comparing with the experimental results. The maximum heat transfer capacity increases with the vapor core radius increasing. Compared with the inclination angle of0°, the maximum heat transfer capacity increases at the larger inclination angle, and the change with temperature is larger. The performance of heat pipe with triangular grooved wick is greatly influenced by gravity, so it is not recommended to be applied to the dish solar heat pipe receiver.

Study on fracture characteristic of welded high-density polyethylene pipe

Crack opening displacement(COD) was applied to characterize the fracture initiation of the tough high density polyethylene. Normal single side notched three point bend specimens and silica rubber replica techniques were used to study the characteristic COD of high density polyethylene pipe and its butt fusion joints including the weld fusion zone and heat affected zone at different temperature from -78 ℃ to 20 ℃ . Testing results show that the characteristic COD appears to depend on the structural features that are determined by welding process and the testing temperature. As the temperature is lowered, the characteristic COD of all zones studied decreases. Because the welding process significantly changes some structural feature of the material, characteristic COD of the weld fusion zone is the smallest one among those of the three zones. The results can be used for the engineering design and failure analysis of HDPE pipe.

Development of the High Toughness Spirally Submerged Arc Welded Pipe Line

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A Study on the Characterization of Mechanical Properties of Grade X80 High Strain Line Pipe Steel

This paper introduces mechanical and metallurgical properties of 27mm thick Grade X80 high strain line pipe steel which aims at constructing long distance natural gas over permafrost and seismic areas.The steel is molybdenum and boron free.Dual phase of the X80 steel plates are regulated by thermal-mechanical controlled processing.The outer diameter of 1219mm pipes are manufactured by UOE process.DWTT toughness and longitudinal tensile properties including the Rt0.5/Rm,Rt1.5/Rt0.5 and Rt2.0/Rt1.0 are analyzed on both the plates and the pipes.Strain aging properties are also evaluated on the base material of the pipe,demonstrating that the pipe complies well with the pipeline construction requirements.Strengthening effects of precipitates are analyzed,revealing a 58.1MPa strengthening contribution by precipitates less than 20nm in size.Dislocation hardening is approximately 176MPa in the present studied steel.

Stress Corrosion Cracking of High-strength Drill Pipe in Sour Gas Well

In high sour gas reservoir drilling process, it happens occasionally that high-strength drill pipe suffers brittle fracture failure due to stress corrosion cracking, and poses serious hazard to drilling safety. To solve this problem, this paper studied the stress corrosion cracking mechanism and infl uencing factors of highstrength drill pipe in sour environment with hydrogen permeation experiments and tensile tests. We simulated practical conditions in laboratory and evaluated the stress corrosion cracking performance of the high-strength drill pipe under conditions of high stress level. For the problems occurring in use of high-strength drill pipe on site, the paper proposed a technical measure for slower stress corrosion cracking.

淮南矿区高位定向长钻孔大直径筛管瓦斯抽采技术

为解决高位定向长钻孔在治理采空区瓦斯中,瓦斯抽采通道易堵塞影响瓦斯抽采效果的问题,提出了高位定向长钻孔内全孔段下筛管技术,通过对高位定向长钻孔全孔段下不同直径筛管技术研究,在潘三矿开展现场试验,试验结果表明,全孔段下φ73 mm大直径筛管能够有效提高高位定向长钻孔瓦斯抽采效果,不仅提高了钻孔瓦斯抽采稳定性和有效抽采孔段比例,而且钻孔平均瓦斯抽采浓度由19%提高至45%,形成了适用于淮南矿区顶板高位定向长钻孔大直径筛管治理采动卸压瓦斯技术,显著提高淮南矿区采动卸压瓦斯治理效果。

Development of pipeline steel at Baosteel over the last 20 years

This study reviews the development of Baosteel＇ s pipeline steel over the last 20 years. Energy demand accelerates the development of high-grade pipeline steel as well as modem petroleum and natural gas pipeline construction. Pipeline steel is a kind of typical modem microalloyed steel produced via thermo-mechanical controlled processing. The development process of pipeline steel at Baosteel represents the course of the technological progress of pipeline steel in China. In the last two decades, Baosteel＇ s pipeline steel has been developed from a single product of hot- rolled strips to a variety of products including hot-rolled strips, heavy plates, high-frequency electric resistance welded （HFW） pipes and U-ing-O-ing-Expanding （UOE） welded pipes. Moreover, the proportion of the HFW and the UOE welded pipes has been increasing year by year. UOE longitudinal submerged arc welding （SAW） pipes have become the leading product of strategic significance in Baosteel＇ s pipeline steel family. Over the last 20 years, Baosteel＇ s pipeline steel products have shifted from ＂ferrite ＋ pearlite＂ X52 to ＂acicular ferrite＂ XT0 and X80, and Baosteel has developed hydrogen-induced cracking （HIC） resistant pipeline steel. Baosteel＇ s pipeline steel products have been applied in variety of geographical areas,including deserts, Gobi, mountains,plains as well as the ocean. And both the X100 and the X120 ultra high strength pipeline steels have been produced on a trial basis. Baosteel has accumulatively produced 6.5 Mt of pipeline steel for both domestic and overseas projects. Baosteel will continue strengthening its strategic cooperation with oil companies, and conducting research on ultra high strength pipeline steel, pipeline steel for strain-based design and submarine pipeline steel,etc. , so as to meet the need of construction in the future.

Discussion on New Evaluation Technology of Non-Metallic Composite Continuous Pipe for Oil and Gas Field

In view of the serious lack and lag of the test and evaluation technology of non-metallic composite continuous pipe, and focusing on the characteristics of the application of non-metallic composite continuous pipe in oil field, this paper discusses a series of new full-scale test and evaluation technologies for accurately evaluating the product quality and practical application performance of non-metallic composite continuous pipe, which effectively solves the major technical problem that the new products of non-metallic pipe cannot be accurately evaluated. Based on the characteristics of the application of non-metallic composite continuous pipe in oil field, a series of new full-scale test evaluation technologies which can accurately evaluate the product quality and practical application performance of non-metallic pipe are designed through a large number of tests. The test and evaluation technology can accurately evaluate the key performance of high and low pressure cycle, high and low temperature cycle, gas permeability resistance, minimum bending radius etc. It provides a scientific evaluation basis for the standardized application of non-metallic continuous pipe and a reliable quality control method for the selection of products in oil field.

Risks of non-conservative design according to ASME B31.1 for high-temperature piping subjected to long-term operation in the creep range

This study investigates the risks of non-conservative piping design according to ASME B31.1 for hightemperature piping subjected to long-term operation at high temperature in a creep regime based on a sensitivity analysis of the hold time. Design evaluations of hightemperature piping were conducted over a range of hold times in the creep regime according to ASME B31.1,which implicitly considers the creep effects, and the French high-temperature design code of the RCC-MRx, which explicitly considers the creep effects. Conservatisms were quantified among the codes in terms of the hold times. In the case of B31.1, the design evaluation results do not change depending on the hold time at high temperature,whereas in the case of RCC-MRx, they do. It was shown that the design limits of RCC-MRx were exceeded when the hold time exceeded certain values, whereas those of B31.1 were satisfied regardless of the hold times. Thus, the design evaluations according to B31.1 did not consistently yield conservative results and might lead to non-conservative results in the case of long-term operations in the creep range.

Motion behavior of non-metallic particles under high frequency magnetic field

Non-metallic particles, especially alumina, are the main inclusions in aluminum and its alloys. Numerical simulation and the corresponding experiments were carried out to study the motion behavior of alumina particles in commercial pure aluminum under high frequency magnetic field. At the meantime, multi-pipe experiment was also done to discuss the prospect of continuous elimination of non-metallic particles under high frequency magnetic field. It is shown that: 1) results of numerical simulation are in good agreement with the experimental results, which certificates the rationality of the simulation model; 2) when the intensity of high frequency magnetic field is 0.06 T, the 30 μm alumina particles in melt inner could migrate to the edge and be removed within 2 s; 3) multi-pipe elimination of alumina particles under high frequency magnetic field is also effective and has a good prospect in industrial application.

High Density Plasma Nitriding of Al-Cu Alloys for Automotive Parts

Duralumin alloys have been utilized as structural components and parts for aircrafts, train-cars and so forth. Their high specific strength was attractive to those applications; however, their little corrosion resistance and low wear endurance became a fatal demerit in practical applications. In order to overcome these issues of high strength aluminum alloys, high density plasma nitriding is proposed as an effective surface treatment for duralumin. This process has a capability to control the RF- and DC-plasmas independently for nitriding. This enables us to temporally control and describe the plasma state by in-situ plasma diagnosis. This plasma diagnosis was instrumented to search for optimum processing condition to plasma nitriding the duralumin alloys of type A2011. Both type A2011 aluminum alloy plates and pipes were employed to describe the inner nitriding behavior for hardening the duralumin alloys by the present plasma nitriding.

高强钢管超高性能混凝土短柱轴压承载力性能试验研究

为研究高强钢管内填超高性能混凝土(UHPC)的钢管混凝土短柱轴压性能,该文设计22根高强钢管UHPC短柱进行轴压试验,从破坏模式、荷载-纵向应变关系对试件的轴压性能进行对比分析,旨在通过径厚比、混凝土强度、截面类型等变化来探究高强钢管UHPC短柱的实际承载力性能差异.试验结果表明:高强钢管UHPC短柱的轴压性能受径厚比、混凝土强度影响较大;试件承载力随钢管壁厚增加而增加,但相同钢管直径和不同钢管直径增幅呈现不同规律.该文从延性、核心混凝土强度提高程度两个角度进行分析并提出高强钢管混凝土试件的相关参数设计建议.最后,将高强钢管UHPC短柱的轴压试验承载力结果与国内外规范GB 50936—2014、AIJ计算承载力结果进行对比,并基于极限平衡理论推导出高强圆钢管UHPC试件的轴压承载力计算公式,同时结合该文试验数据对其进行验证,证明了公式的准确性.

Effect of La_2O_3, Y_2O_3 Additives on Structure and Mechanical Property of Ceramic-Lined Composite Pipe Under Centrifugation

The effect of additives containing rare earth elements La and Y on the structure and mechanical property of ceramic-lined composite pipe was studied in presence of centrifugation. The fracture and shearing strength of ceramic-lined composite pipe containing different additives were measured and analyzed through the fracture and shearing strength experiments. The distribution of shear stress on the interface of ceramic layer and the pipe is computed by finite element method.

盾构隧道下穿高铁路基变形影响规律及加固优化研究

为研究盾构隧道下穿高铁路基施工时对路基的影响规律,探究在隧道开挖过程中运用不同加固措施对既有高铁路基的影响程度。以西安市某地铁工程为依托,利用室内模型试验对比分析盾构隧道下穿高铁CFG桩复合路基过程中,无加固、超前管幕工法加固与地表袖阀管注浆加固3种隧道施工条件下,地表沉降值和沉降槽的空间分布规律;采用数值模拟分析验证超前管幕工法加固工况下盾构隧道下穿时,高铁路基、道床的位移变化规律。室内模型试验结果表明:盾构隧道施工中采用管幕工法加固后复合地基正上方的地表沉降最大值减小28.6%,采用袖阀管注浆加固后减小18.0%,并且采用两种加固措施后的CFG桩最大附加轴力均减小20%以上。因此,在隧道掘进过程中采用一定加固措施,可改善围岩稳定性,其中管幕工法加固效果更为显著。数值模拟分析表明:采取管幕工法加固施工与不采取加固措施相比,路基最大沉降量减少33.78%,道床最大沉降量减少45.08%。因此,管幕工法加固能够有效减小对既有高铁路基的影响。

高填方大直径钢波纹管涵变形机制与控制技术研究

目的 研究高填方大直径钢波纹管涵变形机制与控制技术,解决其结构变形过大的问题。方法 基于管道压缩变形公式,提出在管涵两侧一定范围内填筑水泥土材料的新技术;通过室内试验确定水泥土材料中最优水泥质量分数,再基于数值模拟和现场试验分析采用新技术施工的管涵结构的受力及变形特征及其上部竖向土压力分布规律,确定最优管侧填筑范围。结果 新填筑技术能充分利用水泥土的刚度限制管涵的变形,当管涵两侧2/3管径范围内采用水泥质量分数为8%水泥土回填时,管涵的最大竖向及水平变形分别减少了35.1%和55.0%,结构最大应力也由管顶处转移至管涵上部45°附近,受力更为合理。结论 新填筑技术使管涵更好地与周围土体逐步变形协调,产生荷载重分布形成土拱效应,将管顶土压力由管中心向管边缘处转移,有效减小了钢波纹管涵结构变形和应力集中。

锅炉水冷壁管失效分析

锅炉水冷壁管材料为20G钢,在320℃和10.3 MPa下使用约5年后外表面出现鼓包并泄漏。对失效的水冷壁管进行了宏观检查、化学成分分析、力学性能检测、金相检验、腐蚀产物分析及锅炉水质检测。结果表明:水冷壁管失效是由于锅炉水碱性超标从而发生高温碱腐蚀所致。