Material Degradation Analysis and Reliability Assessment of Residual Life for Service-Exposed Reformer Tubes

2020 ◽  
Vol 29 (8) ◽  
pp. 5458-5466
Author(s):  
Zhiyuan Han ◽  
Luowei Cao ◽  
LiKun Wang ◽  
Chenyang Du ◽  
Xiaolong Qian ◽  
...  
2017 ◽  
Vol 897 ◽  
pp. 743-746 ◽  
Author(s):  
Satoshi Tanimoto ◽  
Tatsuhiro Suzuki ◽  
Sawa Araki ◽  
Toshiharu Makino ◽  
Hiromitsu Kato ◽  
...  

The long-term reliability of Schottky pn diodes (SPNDs) on diamond having widely used Ti/Pt/Au electrodes was investigated at 500°C in order to identify degradation phenomena at higher temperatures. A vital degradation event was observed after the passage of about 100 hours in that both forward and reverse currents were progressively reduced. AES depth profiling and X-STEM-EELS analyses revealed that this occurred because the Ti contact material changed to insulating (or semiconductive) TiO2, causing large series resistance.


2019 ◽  
Vol 795 ◽  
pp. 239-245
Author(s):  
Zhi Yuan Han ◽  
Guo Hao Sun ◽  
Guo Shan Xie ◽  
Luo Wei Cao ◽  
Zhen Jie Li

This study investigated the microstructural characteristics and property degradation of service-exposed reformer tubes. The reformer tubes were graded into three damage levels based on on-site ultrasonic testing. The microstructural and mechanical experiments were carried out included optical observations, scanning electron microscope (SEM) observations, room temperature tensile tests, high temperature tensile tests, and stress rupture tests. The results showed that the coarsen of carbides occurred during service. A decrease of tensile elongation was observed. The mechanical properties and rupture behaviours of reformer tubes for different inspection levels were also obtained. The results showed that the ultrasonic inspection levels of tubes could be significantly influenced by carbide morphology of tube materials. A residual life of 8.3 years was estimated for these tubes.


2006 ◽  
Vol 2006.1 (0) ◽  
pp. 483-484
Author(s):  
Motoki NAKAJIMA ◽  
Tetsuya HONDA ◽  
Shin-ichi KOMAZAKI ◽  
Yutaka KOHNO

2015 ◽  
Vol 647 ◽  
pp. 162-169
Author(s):  
Lenla Pekařová ◽  
Zdeněk Kuboň

Routine non-destructive examination of the steam pipe elbow after more than 240 000 hours of operation at elevated temperature revealed the extensive creep damage on the outer surface of the pipe elbow. Complex metallographic analysis made in this area confirmed creep damage as well as the non-uniform nature of the cavitation. The density of cavities continuously decreased from the outer pipe surface towards the inner surface, but also its density rapidly waned beyond the damaged area in both directions, along the circumference as well as the length of the elbow. The actual extent of the material degradation was then evaluated by testing of mechanical properties, Charpy-V and fracture toughness testing and the results were used in calculation of the residual life of the pipe elbow. It was shown that although the creep damage was perhaps one of the worst detected in Czech Republic, the cracks in the pipe elbow would spread by the stable growth until the half of the pipe wall thickness. This result thus confirms the possibility of creep life extension far beyond the limit criteria used so far.


2009 ◽  
Vol 106 (9) ◽  
pp. 093110 ◽  
Author(s):  
W. Lu ◽  
S. Bull ◽  
J. J. Lim ◽  
R. MacKenzie ◽  
S. Sujecki ◽  
...  

Author(s):  
Zhiyuan Han ◽  
Guoshan Xie ◽  
Luowei Cao ◽  
Likun Wang ◽  
Guohao Sun

Abstract Reformer furnaces are widely used in a hydrogen plant to obtain hydrogen from hydrocarbon. The radiantt coils tubes are the most critical components of a reformer furnace, which can be heated up to 850 °C or higher temperature for long time during service. The failure of tubes usually happened before the designed life due to over-heating or unexpected damage, which usually leads to unplanned shutdown of plant and great losses. Thus, it is important to assess the damage conditions and residual life of furnace tubes. This study is an attempt to investigate the property degradation and residual life for service exposed reformer tubes of a hydrogen reformer furnace after 6 years service. Microstructural and mechanical experiments were carried out to reveal the property degradation, included optical observations, scanning electron microscope (SEM) observations, room temperature tensile tests, high temperature tensile tests, and stress rupture tests. Finite element analysis was also used to investigated the influence factors on the stress of tubes. The residual life of furnace tube was estimated based on these experimental and simulation results.


2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Haoyun Yuan ◽  
Wei Hou ◽  
Leping Ren ◽  
Xiaojin Zhao

In recent decades, carbon fiber reinforced plastics (CFRP) have been widely used to repair and maintain concrete structures around the world. Since the parameter uncertainties of load and resistance are very important for the reliability assessment of RC bridge strengthened by CFRP, this paper presents a method to estimate the reliability and residual life of RC bridges strengthened by CFRP. In the proposed method, uncertainties of material properties, geometry parameters, load model, and time-dependent resistance model are taken into account. The proposed method combines the inverse reliability method and the calculation method of load and resistance of RC bridge strengthened by CFRP and is illustrated by an example RC bridge strengthened by CFRP during the service stage. The results indicate that the proposed approach can provide valid information regarding parameter uncertainties for the reliability of RC bridge strengthened by CFRP during the service stage. Additionally, the effects of parameter uncertainty of the reliability and residual life of RC bridge strengthened by CFRP during the service stage are analyzed and discussed. The proposed method is more robust and reliable than the traditional method.


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