Material degradation and embrittlement evaluation of ethylene cracking furnace tubes after long term service

Han, Zhiyuan; Xie, Guoshan; Cao, Luowei; Wang, Likun

doi:10.1016/j.engfailanal.2019.01.041

Cited by 17 publications

(12 citation statements)

References 10 publications

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“…Similarly, the HP40Nb reformer tube failed in 7 years of service when the tubes operating at 870°C were exposed to temperatures higher than the design for short durations. The tensile strength and elongation of the tube specimens exposed to 1000°C were significantly lower due to the microstructural degradation [7]. The overheating of the tubes accelerates the dissolution of secondary carbides and coarsening of primary carbides at the inter-dendritic boundaries [1,5,7], leading to the initiation of creep cavities.…”

Section: Introductionmentioning

confidence: 99%

“…Creep embrittlement is the predominant failure mechanism in cast reformer tubes in the fertilizer, petrochemical, and petroleum refining industries [1][2][3][4][5][6][7]. Reformer tubes are used in the process industry for the production of hydrogen by reaction between natural gas and steam in the presence of a catalyst.…”

Section: Introductionmentioning

confidence: 99%

“…In service, when exposed to high temperatures, microstructural changes occur in reformer alloys with precipitation of secondary carbides along with intermetallic secondary phases [9,10,[14][15][16][17][18][19][20][21][22][23][24][25]. The precipitation of secondary phases that occurs during high-temperature service drastically affects the mechanical properties of the reformer tubes [7,8,18,21]. The high-temperature exposure for prolonged durations can also lead to the initiation of creep voids in the material.…”

Section: Introductionmentioning

confidence: 99%

“…The primary carbide network typically consists of chromium-rich Cr 23 C 6 and niobium-rich carbides, which get enriched with other alloying elements during high-temperature service [3,22]. Continued exposure of the tubes to high temperatures can lead to coarsening and coalescence of the precipitated secondary carbides [3,7,26]. The reformer tubes were designed for a life of 100,000 hours at the operating temperature.…”

Section: Introductionmentioning

confidence: 99%

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Creep Failure of 25Cr-35Ni Centrifugally Cast Reformer Tube

Ravindranath¹,

Akbar²,

Al-Wakaa³

et al. 2023

Failure Analysis - Structural Health Monitoring of Structure and Infrastructure Components

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Cast 25Cr-35Ni alloys are extensively being used in the petrochemical and petroleum refining industries for high-temperature applications. A typical application of such alloys in the industry is in the manufacture of cast catalyst reformer tubes for the production of hydrogen. The cast 25Cr-35Ni catalyst reformer tubes possess the required mechanical properties, creep resistance, oxidation resistance, and high-temperature stability. Though reformer tubes are designed to give a service life of over 100,000 hours at temperatures beyond 900°C, there are incidents of failure due to creep damage, which is the predominant failure mechanism in reformer tubes. The paper discusses an investigation conducted on the premature failure of a 25Cr-35Ni reformer tube. The investigation involved microstructural assessments and the evaluation of mechanical properties. The microstructure and mechanical properties of the service-exposed reformer tube were also compared with a new tube. The investigation revealed that the failure of the tube was due to creep embrittlement. The creep embrittlement was due to the microstructural degradations that occurred as a result of overheating. Adherence to the design and operational parameters is critical in mitigating creep embrittlement failures.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Creep Failure of 25Cr-35Ni Centrifugally Cast Reformer Tube

Ravindranath¹,

Akbar²,

Al-Wakaa³

et al. 2023

Failure Analysis - Structural Health Monitoring of Structure and Infrastructure Components

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“…During the operation of the furnace tube, the outer wall of the tube in service is radiated by high temperature flame and its ambient temperature can reach 1100℃. The raw material inside the tube is a mixture of high carbon potential hydrocarbon gas and water vapor, therefore its inner wall is in the environment of circulating oxidation and carburizing, and its outer wall is in the environment of high-temperature oxidation and decarburization; besides, the ethylene cracking furnace tube is subject to additional stresses caused by internal pressure in the tube, body weight of the tube, temperature difference between the inner and outer walls and on/off process; working in such environment, carburizing, thermal fatigue, creep and other damages are quite easy to occur in the cracking furnace tube and its actual service life is often far lower than the design life [1][2][3][4][5][6][7][8]. Carburizing is the main damage form of ethylene cracking furnace tubes.…”

Section: Introductionmentioning

confidence: 99%

Microstructure Evolution and Element Redistribution in Carburizing Process of Ethylene Cracking Furnace Tube

Zhang

Ding

et al. 2022

Advances in Transdisciplinary Engineering

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Carburizing is the main damage form of ethylene cracking furnace tubes. In this process, the microstructure of the furnace tube would change and the element diffuses and redistributes. After serving for about 41000h, the radiation section of a plum blossom tube of SC-1 tubular cracking furnace from a petrochemical company was tested and analyzed in this article. Results show that the higher the service temperature, the more serious the carburizing of the furnace tube. In the inner-wall carburized zone of the middle temperature section of the furnace tube with an initial C content of 0.1wt%, the maximum C content reaches 1.83wt% and the number of carbides increases obviously as well as its organizational morphology changes from fine granular to coarse block or chain like and its organizational type changes from single M23C6 to the coexistence of M23C6, M7C3 and MC type carbides. The Cr and C elements in the carburized zone are mainly concentrated in the grain boundary area in the form of carbides. At the same time, the diffusion of alloy elements causes Cr deficiency in the matrix, and the carbide deficiency zone appears in the subsurface of the inner wall.

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