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。     

锅炉HR3C不锈钢末级过热器管泄漏原因

某超超临界锅炉末级过热器管发生泄漏事故,通过宏观观察、化学成分分析、力学性能试验、金相检验和能谱分析等方法,对过热器管的泄漏原因进行了分析.结果表明:HR3C不锈钢末级过热器管材料中存在晶间氧化和原始内折叠缺陷,采用水浸法超声波检测未检出,运行过程中在缺陷部位产生应力集中并萌生裂纹源,裂纹在轧制过程中的交变应力作用下沿...     

锅炉向空排汽管管孔裂纹原因分析及改进措施

一、概述某电厂1#锅炉过热器出口集箱(φ273×25,12Cr1MoV)上的向空排汽管(φ76×6,12Cr1MoV)角焊缝热影响区多次发生裂纹,导致泄漏,严重影响锅炉安全运行。在更换管座重新焊接时,发现集箱管孔有放射性裂纹,对此种裂纹和形成进行原因分析,并提出改进措施。     

75t／h循环床锅炉高温过热器蛇形管泄漏分析

对７５ｔ／ｈ循环床锅炉高温过热器蛇形管裂纹及泄漏事故进行了分析。确认管内壁的腐蚀坑与碱性介质的综合作用诱导了苛性脆性裂纹的发展，使过热器早期失效。提出了防护措施。     

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。     

沸腾锅炉入炉煤粉煤过多对燃烧的影响

本文论述了燃用无烟煤的沸腾锅炉入炉煤中１ｍｍ以上的粉煤所占的比例超过５０％以上就会造成炉膛出口温度严重超标，会引起过热蒸汽温度超温，严重时会导致顶棚管和过热器管上结焦，并以炉膛出口温度严重超标和过热器管迎风面上结焦的原因进行了分析，同时提出了几点改进措施。     

锅炉过热器管爆裂原因分析

某锅炉过热器管在运行约1a(年)后发生爆裂。对爆裂管进行了断口宏观及微观分析、化学成分分析、硬度测试和金相检验,以分析其爆裂原因。结果表明:该锅炉过热器管长时间处于高温高压的运行条件下,管件内表面产生了较厚的氧化皮,导致局部管壁温度升高;过热器管显微组织严重劣化,粗大的碳化物颗粒析出并在晶界富集长大,导致晶界弱化;晶界处出现裂纹并不断扩展,最终导致管件爆裂。     

锅炉过热器管弯头开裂失效分析

某12Cr1MoVG钢锅炉在投入使用数月后发现过热器管弯头处发生开裂.采用光学显微镜、显微硬度计、扫描电子显微镜和能谱仪对锅炉过热器管弯头开裂进行了失效分析.结果 表明:过热器管弯头失效的主要原因为碱性环境下的应力腐蚀和氢脆,过热器管弯头在运行过程中局部存在浓缩碱溶液,浓缩碱溶液在高温和水的作用下腐蚀管道内壁并生成微量的氢,氢在残余应力的作用下侵入金属内部并在晶界处聚集引发氢脆,这是造成弯头内壁形成大量沿晶裂纹的根本原因.     

锅炉过热器管爆裂原因分析

针对某热电厂4号锅炉12CrlMoV钢过热器管的爆裂破坏,进行了宏观形貌、化学成分、金相组织、扫描电镜等的分析。结果表明,炉管爆裂的原因是炉内局部温度过高,该处炉管长期过热,管壁组织珠光体球化达到5级．晶界出现蠕变裂纹,导致炉管强度降低所致。     

SG—1025／183-M317型炉再热器穿顶棚管、泄漏原因分析及改造

本文详细分析了广东沙角A电厂4、5号锅炉（SG-1025／183-M317型）再热器穿顶棚管泄漏的原因,提出了对其进行技术改造的方案,可供同类炉型锅炉设计与改造时参考。     

Failure analysis and retrofitting of superheater tubes in utility boiler

The extreme spray water mass flow rate deviation was observed to occur in the middle temperature superheater of Sahand 2 × 325 MW Power Plant utility boiler, which severely affected its economic performance and safe operation. Boilers operating in these conditions led to failure in superheater tubes at the same place for two consecutive times in a three year span. Thus, the failure analysis of superheater tubes by investigating the visual inspection, chemical, scale and creep analysis was carried out. The brittle failure occurred in the superheater tubes after the fuel was changed from natural gas to heavy oil. Failure analysis showed that tubes were suffering from long term overheating which was instigated by high spray water flow rate. In order to rectify the boiler operating conditions, some modifications were applied in the boiler unit 1 and operating parameters on this boiler were compared with boiler unit 2. The results showed that the 8.33% reduction in heating surface area corresponds to 52.84 and 17.80% reduction in spray water mass flow rate for capacities equal to 300 and 260 MW, respectively.     

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.     

Erosion-corrosion behaviour of Ni-based superalloy Superni-75 in the real service environment of the boiler

The super-heater and re-heater tubes of the boilers used in thermal power plants are subjected to unacceptable levels of surface degradation by the combined effect of erosion-corrosion mechanism, resulting in the tube wall thinning and premature failure. The nickel-based superalloys can be used as boiler tube materials to increase the service life of the boilers, especially for the new generation ultra-supercritical boilers. The aim of the present investigation is to evaluate the erosion-corrosion behaviour of Ni-based superalloy Superni-75 in the real service environment of the coal-fired boiler of a thermal power plant. The cyclic experimental study was performed for 1000 h in the platen superheater zone of the coal-fired boiler where the temperature was around 900°C. The corrosion products have been characterized with respect to surface morphology, phase composition and element concentration using the combined techniques of X-ray diffractometry (XRD), scanning electron microscopy/energy-dispersive analysis (SEM/EDAX) and electron probe micro analyser (EPMA). The Superni-75 performed well in the coal-fired boiler environment, which has been attributed mainly to the formation of a thick band of chromium in scale due to selective oxidation of the chromium.     

电厂锅炉末级过热器爆管原因分析

在长期过热的运行工况下,锅炉高温过热器极易产生材料的劣化以及材料组织和性能的下降,最终引发爆管事故。通过宏观检查、布氏硬度测试、抗拉强度测试和金相组织检验对某电厂末级过热器爆管原因进行分析。结果表明,该末级过热器管由于在长期高温高压下超温运行,导致碳化物在晶界富集,晶界强度下降,在拉应力的作用下,晶界产生蠕变空洞及蠕变裂纹,使得珠光体耐热钢的持久强度和抗拉强度下降,最终产生断裂失效。     

220t/h锅炉过热器管破裂分析

某220t／h锅炉高温过热器管在试运行时发生破裂。采用金相检验、化学分析及热处理试验等手段对裂管进行了解剖分析。结果表明，由于有一种富碳物质堵塞了过热器管道，致使堵塞区域出现超温现象，并使该区域的管内壁生成一层共析组织，大大降低了管材的力学性能，最终导致管道破裂。     

Research on Remaining Life Evaluation Method of T92 Steel for Superheater Tube Based on Oxide Layer Growth

Journal of Failure Analysis and Prevention - T92 steel is widely used in high-temperature superheater of supercritical power station boiler, and the researches on its remaining life have always...     

Investigation of Premature Failure of a Coal-Fired Boiler Superheater Tube

Journal of Failure Analysis and Prevention - A metallurgical investigation has been carried out to ascertain the cause of premature failure of boiler superheater tube. The tube material was...     

超超临界机组锅炉末级过热器爆管原因分析

通过化学成分分析、金相检验、力学性能测试等手段对某电厂超超临界锅炉末级过热器T91钢管爆裂原因进行了分析。结果表明:爆管系超温运行所致,过热导致钢管材料显微组织老化、力学性能显著下降;并根据现场情况对爆裂管的超温原因进行了分析,认为异物堵塞造成超温的可能性较大。     

Remnant life assessment of service-exposed pendent superheater tubes

Remnant life assessment and life extension has become an integral part of plant maintenance activities, Cr–Mo steels are widely used in thermal power plants at a temperature of about 550°C. This paper deals with the high temperature tensile and creep rupture properties of 1Cr–0.5Mo steels for pendent superheater tubes in a boiler of a thermal power plant after five years service exposure for 43,000 h. Based on stress vs Larson Miller Parameter plot and at the operating hoop stress level, the pendent superheater tubes in general are found to be in a good state of health and can continue to remain in service for a length of 10 years, provided the temperature of the tube is brought down below 500°C. This observation may not be true for those selected tubes where already expansion in the diameter has taken place. Such tubes should be identified and replaced. In the case that it is not possible to bring down the temperature below 500°C, it may be desirable to use a superior grade of material like 2.25Cr–1Mo or 9Cr–1Mo steel. A thicker tube of the same grade may also be considered provided the overall load of the panel does not exceed the limit. It is, however, recommended that a similar health check be carried out after five years.