Metallurgical Investigation of a Prematurely Failed Concentric Reducer Tube Used in a Hot-Rolling Mill

A concentric reducer tube, which was a part of the top exit roughing hydraulic descaler in a hot strip mill failed prematurely under working pressure. A detailed metallurgical investigation comprising physical examination, optical microscopy, scanning electron microscopy, and electron probe microanalysis was carried out to find out the genesis of the failure. Physical examination revealed cracks located symmetrically around the circumference of the tube that ran along its full length, up to the weld beads at both ends. Optical microscopy of etched samples revealed a banded ferrite-pearlite structure and the existence of forging folds near the change-in-section(160° fillets). Cracks were found to initiate from these forging folds. No structural abnormalities were found in the weld beads and heat-affected zones.     

城市供水管网漏损探讨

就漏损控制这一项复杂的系统工程，详细地介绍了我国城市供水管网的漏损现状，分析了进行漏损控制产生的效益，造成漏损的主要原因及防治措施，提出漏损量的大小是衡量供水管网技术技术和运行的重要指标。     

2RE69/Zr702双金属管氨汽提塔关键部件的设计与制造

介绍了2RE69／Zr702双金属管的特殊结构、优良耐蚀性能，与管板的连接接头型式及焊接工艺、管头及液体分布器加工、装配和试验。     

Assessment of service exposed boiler tubes

Boiler tubes in power plants have finite life because of prolonged exposure to high temperature, stress and aggressive environment. Service-exposed platen superheater and reheater tubes (148,900 h) made of 2.25Cr-1 Mo steels in a 120 MW boiler of a thermal power plant were evaluated for remnant life. The investigation included hot tensile tests, hardness measurement, dimensional measurement, microscopy and creep tests. Experimentally determined yield and ultimate tensile strength, and estimated 10,000–100,000 h rupture strength in the temperature range 520–580 °C, exhibited a decreasing trend with increasing temperature. Microstructural study did not reveal any significant degradation in terms of creep cavities, cracks, graphitization, etc. Analysis of tensile and stress rupture data revealed that although there was degradation of the tubes due to prolonged service exposure in terms of the ultimate tensile strength values, stress rupture plots showed that the service exposed superheater and reheater tubes could remain in service for a length of more than 10 years at the operating hoop stress of 40 MPa/540 °C, provided no localised damage in the form of cracks or dents develop.     

联合循环余热锅炉螺旋鳍片管烟气放热系数研究

东南大学建造了1座IGCC余热锅炉鳍片管受热面流动和传热热态试验装置,并先后在其上进行了2个不同螺旋鳍片管组的传热特性研究,通过分析比较实测的烟气侧对流放热系数与无量纲准则式计算的结果,得出了完全热模拟公式更为准确的结论。     

管内覆丝网强化对流换热及阻力特性的实验研究

通过实验对管内覆丝网管进行了强迫对流换热和阻力特性研究。结果表明：管内覆丝网使换热明显增强，阻力也相应增长。菱形丝网对角线距离与平行边距离之比对换热效果有决定作用，丝网厚度对换热的影响比较小，而丝网网格的大小对换热几乎没有影响，在相同的泵功率和几何条件下，换热系数最大增加２１％。     

锯齿型螺旋翅片管束传热与阻力性能的分析研究

对气流横掠锯齿型螺旋翅片管管束的对流传热进行了试验研究，并通过了工业试验验证，得出了相应的传热和阻力系数的数学关联式，可供设计计算使用。     

改造加热炉系统 提高加热炉热效率

分析了重整装置加热炉热效率低的原因，介绍了提高加热炉热效率采取的几项措施。     

埕岛油田卫星平台金属软管漏蚀问题的分析和对策

对埕岛油田卫星平台多年来一直存在的金属软管漏蚀问题进行分析,找出了导致金属软管漏蚀的主要原因,提出了相应的防治措施,主要有:在金属软管外部裹附橡胶垫,采用带弯头的减振金属软管,安装时金属软管的曲率半径要大于其最小弯曲半径等。通过采取一系列措施,解决了金属软管的漏蚀问题,达到了预期的效果。     

油管螺纹参数对疲劳寿命的影响

油管螺纹的几何尺寸是衡量油管疲劳寿命的一项重要技术指标。应用有限元在改变螺纹参数的情况下模拟油管几何形貌,计算应力分布并预测其疲劳寿命,针对油管螺纹参数对其疲劳寿命的影响趋势进行了研究。