Creep Failure of Reformer Tubes in a Petrochemical Plant
Abstract
:1. Introduction and Case Background
2. Experimental Methods
3. Results and Discussion
3.1. Visual Examinations
3.2. Microstructure and Chemical Analyses
4. Concluding Remarks
- Tubes have two typical grain structures: (i) dendritic microstructure, starting from the outer surface towards the half-thickness, and (ii) equiaxed grain structure, starting from the half thickness towards the inner surface. This is the typical microstructure of centrifugally cast heat resistant alloys.
- Two types of carbides were present in the microstructure: (i) chromium-rich carbides and (ii) niobium carbides. In most cases, carbides had a “Chinese script” morphology. Carbides were overall coalesced and coarsened to a large extent.
- Creep voids were observed through the thickness of failed tubes. Voids in the dendritic structure region were oriented more alongside dendrites and were seen more often in the inter-dendritic regions. On the contrary, voids in the equiaxed grain structure were more randomly distributed without any directionality.
- Creep voids were nucleated on both chromium and niobium carbides. Cracks were formed due to the growth and coalescence of voids.
- The root cause analysis of the concerned failure showed that tubes failed due to creep failure.
- When it comes to creep failure, the most important factor that controls the lifetime of the components during a high temperature service is temperature. Improper control of temperature and overheating can dramatically decrease the creep lifetime of reformer tubes.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
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Composition | C | Si | Mn | Cr | Ni | Nb | Fe |
---|---|---|---|---|---|---|---|
wt% | 0.41 | 1.2 | 0.9 | 25.5 | 35.6 | 1.3 | Bal. |
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Bahrami, A.; Taheri, P. Creep Failure of Reformer Tubes in a Petrochemical Plant. Metals 2019, 9, 1026. https://doi.org/10.3390/met9101026
Bahrami A, Taheri P. Creep Failure of Reformer Tubes in a Petrochemical Plant. Metals. 2019; 9(10):1026. https://doi.org/10.3390/met9101026
Chicago/Turabian StyleBahrami, Abbas, and Peyman Taheri. 2019. "Creep Failure of Reformer Tubes in a Petrochemical Plant" Metals 9, no. 10: 1026. https://doi.org/10.3390/met9101026