A high pressure gas cooler located in an offshore platform have been operating for more than 10 years. Throughout that period the gas cooler have been subjected to several tube failures, the failures have caused gas leak from the tube side. Several materials upgrades have been used to contain the tube failure. The last choice was to use a more corrosion resistant material Hastelloy C22. Crevice corrosion has been reported as the primary failure mechanism. The tube and tube plate joined surfaces have been exposed to high temperature which is relatively higher than the critical crevice temperature of Hastelloy C22. There was a poor heat transfer between the shell side fluid and tube side due to a small heat transfer area and low fluid velocity in the affected zone. Stress corrosion and fatigue corrosion accounted for the secondary failure mechanism which ultimately caused a crack in the tubes. Other possible reason identified to cause crevice corrosion was the mechanical rolling expansion technique. Oftentimes it creates rear crevices on the tubes with enough geometry to develop crevice chemistry. Mitigation methods such as hydraulic expansion technique, heat treatment for residual stresses and baffle design enhancements have been proposed in this report.
Key words: shell and tube heat exchanger failure; Hastelloy C22 material; tube failure; localized corrosion; crevice corrosion; internal pitting corrosion
Inhaltsverzeichnis (Table of Contents)
- Abbreviations
- Introduction
- 1.1 Methodology
- Failure Investigation
- 2.1 Material description
- 2.2 Service condition
- 2.3 Localized corrosion
- 2.4 Effect of rolling expansion
- 2.5 Stress corrosion
- 2.6 Corrosion fatigue
- 2.7 Effects of temperature
- Discussion
- 3.1 Causes of crevice corrosion
- 3.2 Crevice corrosion mechanism
- 3.3 Stream temperature effects
- 3.4 Causes of pitting
- 3.5 Crack initiation
- Conclusion
- Recommendation to mitigate failure
- 5.1 Tube assembly
- 5.2 Residual stresses
- 5.1 Temperature and baffle design
- References
- Appendices
Zielsetzung und Themenschwerpunkte (Objectives and Key Themes)
This technical report investigates the failure of a high-pressure gas cooler located on an offshore platform. The report aims to identify the root causes of the failures, which have resulted in gas leaks and necessitated material upgrades. The investigation focuses on understanding the failure mechanisms and proposing mitigation methods to prevent future failures.
- Localized corrosion, particularly crevice corrosion, as the primary failure mechanism
- The role of stress corrosion and corrosion fatigue in the failure process
- The impact of high temperatures and poor heat transfer on corrosion
- The influence of mechanical rolling expansion techniques on crevice formation
- Mitigation strategies such as hydraulic expansion, heat treatment, and baffle design enhancements
Zusammenfassung der Kapitel (Chapter Summaries)
- Introduction: This chapter introduces the background of the gas cooler failure, including the service conditions and the history of material upgrades. It also outlines the methodology used for the investigation.
- Failure Investigation: This chapter provides a detailed description of the materials used in the gas cooler, the service conditions, and the localized corrosion observed. It also examines the effects of rolling expansion, stress corrosion, and corrosion fatigue.
- Discussion: This chapter discusses the causes and mechanisms of crevice corrosion, the impact of stream temperatures, and the causes of pitting. It also analyzes the initiation of cracks in the tubes.
- Conclusion: This chapter summarizes the findings of the investigation and provides an overall assessment of the failure mechanisms.
- Recommendation to mitigate failure: This chapter presents recommendations for mitigating future failures, including improvements to tube assembly, residual stress management, and temperature and baffle design adjustments.
Schlüsselwörter (Keywords)
This report examines the failure of a shell and tube heat exchanger, focusing on the use of Hastelloy C22 material. The investigation explores localized corrosion mechanisms, particularly crevice corrosion and internal pitting corrosion, as well as the role of stress corrosion cracking. The report identifies factors such as poor heat transfer, high temperatures, and mechanical rolling expansion as contributors to the failures and proposes mitigation methods for future designs.
- Quote paper
- Ataliba Miguel (Author), 2013, Heat exchanger failure investigation report, Munich, GRIN Verlag, https://www.hausarbeiten.de/document/269681
