PSI - Issue 17

C. Medrea et al. / Procedia Structural Integrity 17 (2019) 526–531

531

C. Medrea, E. Pappa, D.G. Papageorgiou, C. Stergiou / Structural Integrity Procedia 00 (2019) 000 – 000

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Fig. 9. (a) Detail of the first fragments containing all welding zones, (b, c, d) Details showing welding defects on first welding area.

4. Conclusions

The installation was manufactured from two pipes of Incoloy 800H welded together. The material selected is suitable for the specific applications. Its composition was confirmed by positive material identification method. The fitting failure was detected on the mixing area. Specific space is exposed unevenly to high temperature and high pressure and as a result is overloaded. A network of cracks were initiated on the welding zone and propagated towards the surrounding regions. Furthermore, defects associated with poor welding were induced during welding and facilitated the crack propagation. Closer examination indicated that the tee pipe fitting failed by thermal fatigue due to simultaneous effect of stress and temperature. Microscopic examination and hardness measurements will be carried out in order to validate some observations and to propose recommendations.

Acknowledgements

The authors gratefully acknowledge Mr. Dimitris Rigos from the Department of Equipment Inspection, Hellenic Petroleum S.A., for supporting in NDT testing and Mr. Ioannis Rahoutis student at University of West Attica, for supporting the experimental part.

References

ASTM Standard B407, 1996. Standard Specification for Nickel-Iron-Chromium Alloy Seamless Pipe and Tube , Annual Book of ASTM Standards. American Society for Testing and Materials. Gary J.H., Handwerk G.E., 2001. Petroleum Refining Technology and Economics . Ed. Marcel Dekker. Inc. Richard S. Kraus R.S., 2015. ILO Encyclopedia of Occupational Health and Safety. Petroleum Refining Process. Occupational Safety and Health Administration (OSHA). Available at: http://www.iloencyclopaedia.org/ [Accessed 9 May 2019]. K.P.C. Vollhardt, Schore N.E., 2015 Organic Chemistry ; Structure and Function, 6 th Edition, Ed. Freeman and Co. Pappa E., Papageorgiou D.G., Medrea C., Stergiou K., 2018. Preliminary examination of a tee pipe fitting failed in a petroleum refinery unit , 13 th International Scientific Conference, eRa13, Athens, Greece. Technical Fact, 2019. Nickel Alloy 800 , Stainalloy, Available at: https: //www.stainalloy.com/alloy-800/?gclid=EAIaIQobChMIv4Ko9vn54QIVz OR3Ch1JJw6MEAAYASAAEgLwJ_D_Bw, [Accessed 1 May 2019]. Van der Geer A., Hanraads, J.A.J., Lupton, R.A., 2010. The art to writing a scientific article , Journal of Science Communication, 163, 51 – 59.