B-801辅助锅炉过热器炉管运行安全性分析

为了掌握超期服役的B-801辅助锅炉的运行情况，对锅炉二级过热器炉管进行了宏观检查、管径测量与蠕胀分析、超声波测厚、硬度测定、金相检验和强度校核，对其安全性进行了综合分析。分析结果表明，B-801辅助锅炉的二级过热器上部和下部炉管金相组织都未发生石墨化和出现晶界蠕变裂纹；管径胀粗率都在3．5％以下，符合“在用锅炉定期检验规则”的相关规定；其剩余壁厚符合强度要求。综合分析结论认为，锅炉过热器炉管仍能安全运行。     

B-801辅助锅炉安全性评估与剩余寿命预测

对超期服役的B801辅助锅炉炉管进行了宏观检查、管径测量与蠕胀分析、超声波测厚、硬度测定、金相检测和强度校核;并对设备进行了安全性评估和剩余寿命预测.     

某热电厂炉管开裂失效分析

通过对某热电厂开裂失效的炉管进行宏观检验、化学成分分析、力学性能试验、金相检验等分析,确认了引起炉管开裂的原因。结果表明:炉管开裂主要是由于高温环境长期运行导致炉管材料发生蠕变,力学性能下降所致。建议应根据规范要求采取加强炉管服役期间检修时的监测工作,按规范要求在锅炉高温部位设置蠕胀监测点,将炉管的服役期控制在总的相对蠕变应变小于2%之内,以保证锅炉的正常安全运行。     

热水采暖锅炉水冷壁炉管失效分析

对热水锅炉水冷壁爆裂炉管的材质进行了成分分析、强度检测、金相组织分析和内外壁腐蚀产物的X射线衍射分析。经检测,发生爆裂的水冷壁炉管的强度明显降低,炉管的内、外壁发生了严重的氧化脱碳,靠近破口处材质的晶粒异常粗大,珠光体组织严重球化。综合分析表明,局部短时严重超温运行是导致该锅炉水冷壁炉管爆裂的原因。     

15CrMo钢过热器管爆管原因分析

某化工厂电站锅炉15CrMo钢过热器管发生爆管造成整套装置非计划停机。采用宏观检查、化学成分分析、金相检验、管壁形貌分析、硬度测试、胀粗量计算等方法,对过热器管爆管原因进行了分析。结果表明:过热器管爆口有长期过热的特征,由于锅炉超负荷运行及氧化层引起过热器管长期过热,造成管材组织劣化、出现蠕变孔洞及显微裂纹,导致过热器管强度降低最终造成爆管。过热器管的失效模式为长期过热引起的高温蠕变开裂。     

甲醇厂H-1301过热炉炉管焊接工艺浅析

甲醇厂H-1301过热炉经过八年多的运行,部分炉管磨损严重,2015年大修对壁厚减薄15%及以上或胀粗程度超过原管直径的3.5%的炉管进行了更换,本文通过对H-1301过热炉炉管更换焊接工艺进行探讨和分析,为今后类似的相关设备的检修提供借鉴和参考。     

1Cr18Ni9Ti钢炉管开裂原因分析

采用金相检验、力学性能试验、铁磁相含量测定、断口及能谱分析等方法对1Cr18Ni9Ti钢炉管的开裂原因进行分析。结果表明：开裂炉管的内壁裂纹为连多硫酸应力腐蚀开裂,而外壁裂纹为硫化物促进下的氯化物应力腐蚀开裂。并提出了预防炉管开裂的建议。     

乙烯裂解炉辐射段炉管烧损部位的焊接

乙烯裂解炉辐射段炉管长期在恶劣环境中运行，极易发生蠕变、渗碳、氧化腐蚀和热疲劳等破坏。从新旧炉管化学成分、金相组织分析查找烧损原因，制定“堆焊 对焊”的焊接工艺，完成抢修作业的特定任务。     

锅炉水冷却管爆裂原因分析

通过宏观检查、金相检验、化学成分及能谱分析等方法对锅炉水冷却管爆裂原因进行了分析。结果表明:爆裂处管子局部受热,导致显微组织发生变化,使钢管金属材料的力学性能下降,受热面变形,管子慢慢胀粗导致管壁减薄,引起管子鼓包、穿孔直至开裂,造成爆管。     

制氢转化炉管材HP40Nb的失效分析

某石化公司制氢转化炉炉管在运行不到40 000 h后突然破裂起火,宏观检测、表面探伤,力学性能测试,能谱、金相、电镜、X射线、应力等分析表明:炉管材料晶界碳化物过多以及疏松空洞的存在削弱了韧性,产生了较多的微观裂纹,加上管外保温材料中存在较多的Na ,Cl,K ,Mg2 ,Ca2 ,导致下猪尾管到下支耳之间应力较大部位发生应力腐蚀开裂,58号炉管首先开裂泄漏起火,其他炉管在外部火焰烘烤下短时高温损伤、变形鼓包直至开裂.针对失效原因提出了今后使用过程中应采取的防护措施.     

重催装置换热器管束失效分析

重催装置由于特殊的服役环境,多发生介质腐蚀,导致装置泄漏,严重的甚至断裂。针对换热管服役3a后发生腐蚀失效的问题,对其进行宏观检验、化学成分、XRD以及金相组织分析的同时,采用扫描电镜分析换热管微观形貌,用能谱仪对腐蚀产物进行成分分析。结果发现,换热管内表面发生了严重的点蚀,腐蚀产物主要是磁铁矿,腐蚀产物中含有Cl^-和S^2-,这是导致管束失效的主要原因。     

Failure analysis of a steam generator superheater drain tube used in a dump

This paper analyses the failure of a superheater drain tube of a steam generator used in a dump to obtain energy from the biogas produced by organic waste. Chemical and microstructure analyses, together with microhardness measurements, have been performed in order to check any possible deviation from the material specification, finding as the only deviation significant increases in hardness in the failure section, suggesting that the failure section is located in the heat affected zone of a nearby weld. Also, the failure mechanism has been analysed by both visual and SEM inspection of the fracture surface, identifying fatigue as the major cause of the final failure, assisted by corrosion processes. The different areas found on the fracture surface suggest that fatigue processes were caused by the maintenance operation consisting of hitting (hammering) the collector tube to which the drain tube is joined. No evidence has been found in relation to any other anomalous operating conditions, such as overpressure or unexpected high temperatures.     

Failure Analysis and Remaining Life Assessment of Methanol Reformer Tubes

High-quality failure analysis and good engineering judgment can turn plant shutdowns resulting from methanol reformer tube failures into an opportunity to improve the future performance of the reformer furnace. The plant down time can be used to evaluate remaining tube life and provide some insight into the effect of tube operating history, especially tube metal temperature on tube performance. The results can be used to minimize potential future failures and economic losses because of reformer shutdowns. In this article, the failure mechanism of a ruptured reformer tube is determined and an assessment of the remaining life of non-ruptured tubes in the reformer is discussed. Two assessment methods are reviewed (1) metallographic examination of ex-service material to characterize microstructure and creep damage and (2) modeling of creep damage accumulation using special-purpose finite-element software (WinTUBE^TM).     

Failure Analysis of Reformer Tubes

This paper presents a failure analysis performed to investigate cracking observed in reformer tubes. Thorough investigation showed that the tubes failed by thermal shock. No signs of advanced creep failure could be observed near the ruptures or across the microstructure. Also, no material-related abnormalities were observed in the tube microstructure. The reformer tube material is suitable for the application, and there is no need for metallurgy upgrade. It is recommended that reformer operating, start-up and shut down procedures be followed to ensure safe and sustainable operation. The condition of un-replaced tubes that had been exposed to the extreme thermal cycles has to be frequently monitored.     

Plastic collapse of a stainless steel pressurized tube

The failure of a stainless steel tube which conducted oil at 300 °C has been analysed. The fracture surface of the broken tube was studied in the scanning electron microscope and the fracture mechanism found was the nucleation, growth and coalescence of voids. This mechanism is characteristic in materials plastically deformed before failure. Specimens for metallographic examination were cut from the damaged tube and from an intact tube to analyse both microstructures. No significant changes which could justify a microstructure’s embrittlement were detected. Hardness measurements were performed on the damaged and intact tubes. The broken tube was harder than the intact tube due to plastic deformation accumulated during failure. The pressure which is necessary to reach this hardening was analysed by the deformation theory of plasticity and it was found this pressure is close to that corresponding to the plastic instability. Consequently, the most plausible hypothesis of failure was due to an over-pressure which leads to the tube’s plastic collapse.     

Failure and Stress Analysis of Deformed Steel Tube

A deformed steel tube was received for failure analysis. The buckling of the tube had occurred during the heat-treatment operation. The received tube was subjected to different metallurgical tests, and a nondestructive test was also employed to confirm the presence of residual stresses in the tube. It was observed that the microstructure of the tube was homogenous and had no banded structure. However, X-ray diffraction analysis confirmed the presence of up to 6% retained austenite which may have caused the distortion of the tube.     

自行车多飞飞轮轮芯冷挤压凸模具断裂失效原因探析

本文以某自行车集团多飞飞轮轮芯冷挤压模具的凸模为研究对象,通过模具结构的分析、挤压力计算、光学显微镜与扫描电子显微镜的组织结构观察、失效模具断口形貌分析及微区成分测试等探讨了自行车多飞飞轮轮芯冷挤压模具断裂失效的原因。实验发现,失效模具的显微组织中明显存在不均匀带状分布的碳化物,而断裂裂纹发生部位为碳化物集中区。模具组织中存在不均匀带状分布的碳化物是产生断裂失效的主要原因。     

火力发电厂锅炉受热面管泄漏原因分析

一直以来,高温过热器爆管事故都是影响电厂安全运行的主要因素之一,且造成的损失最大。该文结合现场工作的实际对某电厂1号锅炉末级过热器泄漏原因进行了讨论。通过宏观检验、化学成分分析、力学性能试验及显微组织观察等多种试验手段,对该受热面管进行了较为全面的分析,以期对改善锅炉受热面管失效提供帮助。分析得出该末级过热器的泄漏为长时过热所致,泄漏处的显微组织为铁素体加碳化物,珠光体球化达5级,并存在大量蠕变裂纹。     

超超临界机组T92钢高温受热面管爆管原因分析

某电厂的后屏过热器T92钢管段发生爆管。通过宏观检验、化学成分分析、硬度检验、拉伸性能测试、金相检验以及相关计算分析了爆管的原因。结果表明：管段发生短时过热后,其显微组织为Acl-Ac3相变产物,失去了原典型的回火板条马氏体组织特征,材料强度大幅度降低,从而使得强度不足以抵抗管子的使用应力而发生爆管。另外,通过检验获得了不同状态下的组织与性能的对应关系,有利于长期运行中的金属监督检验。     

Metallurgical Failure Analysis of Drum Arching Tube of a 140 MW Thermal Power Plant

This investigation was conducted to examine the probable cause of failure of a drum arching tube at a 140 MW thermal power plant. Preliminary macroscopic examinations along with visual examination, optical microscopy, dimensional measurement, chemical analysis, hardness evaluation, thickness measurement to evaluate extent of damage were carried out to determine the probable cause/causes of failure. It was concluded that the combined effect of corrosion gouging and hydrogen damage were responsible for the failure. Appropriate remedial measures for avoiding such future failures are also recommended.