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Metallurgical Failure Analysis of Cracking in Exhaust Stack Liner Fastening Bolts

Metallurgische Schadensuntersuchung gebrochener Befestigungsbolzen einer Abgaskaminauskleidung
A. Neidel , M. Giller

Madeleine Giller completed an industrial apprenticeship as a materials testing technician at the welding institute SLV Berlin-Brandenburg. She then studied materials science at the TU Berlin, an education she completed with a master's degree in 2012. In the same year, she joined Siemens Gas Turbine Plant Berlin, where she was appointed laboratory manager 2 years later. Her main areas of work are failure analysis scanning electron microscopy.

and S. Riesenbeck

Susanne Riesenbeck joined the Gas Turbine Plant of Siemens' Energy Sector in 1984 and first un-derwent vocational training there. As a materials testing technician, one of the first fields of her professional endevours was steam turbine service, namely remaining lifetime assessment by means of the replica technique. She is a metallographer and one of the principal failure analysts in the materials testing laboratory. Her main fields of expertise comprise microstructural analyses of steel and iron castings.

From the journal Practical Metallography

Abstract

Exhaust stack liners of a test rig for gas turbine burners failed locally by ruptured fasteners and fallen-off liner plates. Misalignment of the plating relative to each other and relative to their fasteners caused restraint of the expanding and shrinking liner plates upon start-up and shutdown of the burner rig. The fastening holes of the failed liner plates were not concentric, but misaligned relative to each other and relative to their fastener bolts. This exerted a shear loading on the threads of the fastening bolts, which in turn caused a mean stress shift and damaged the threads of the fasteners by nicking. So pre-loaded, the fastening bolts were not able to withstand the vibratory loads from the flowing exhaust gases and failed due to fatigue.

Kurzfassung

Bei der Auskleidung des Abgaskamins eines Prüfstands für Gasturbinenbrenner kam es zu lokalem Versagen durch gebrochene Befestigungselemente und abgefallene Platten. Ein Fluchtungsfehler der Platten zueinander und bezüglich ihrer Befestigungselemente führte zur Behinderung der sich beim Anfahren und Abschalten des Brennerprüfstands ausdehnenden und schrumpfenden Platten der Auskleidung. Die Befestigungsbohrungen der entsprechenden Auskleidungsplatten waren nicht konzentrisch, sondern gegeneinander und gegenüber den entsprechenden Befestigungsbolzen versetzt. Dies führte zu einer Scherbelastung der Gewinde der Befestigungsbolzen, die wiederum eine Verschiebung der Mittelspannung bewirkte und eine Beschädigung der Gewinde der Befestigungselemente durch Einkerbungen hervorrief. Derart vorbelastet konnten die Befestigungsbolzen den von den strömenden Abgasen ausgehenden Schwingungsbelastungen nicht standhalten und es kam zu einem Versagen durch Ermüdung.

About the authors

M. Giller

Madeleine Giller completed an industrial apprenticeship as a materials testing technician at the welding institute SLV Berlin-Brandenburg. She then studied materials science at the TU Berlin, an education she completed with a master's degree in 2012. In the same year, she joined Siemens Gas Turbine Plant Berlin, where she was appointed laboratory manager 2 years later. Her main areas of work are failure analysis scanning electron microscopy.

S. Riesenbeck

Susanne Riesenbeck joined the Gas Turbine Plant of Siemens' Energy Sector in 1984 and first un-derwent vocational training there. As a materials testing technician, one of the first fields of her professional endevours was steam turbine service, namely remaining lifetime assessment by means of the replica technique. She is a metallographer and one of the principal failure analysts in the materials testing laboratory. Her main fields of expertise comprise microstructural analyses of steel and iron castings.

References / Literatur

[1] Neidel, A.; Giller, M.; Riesenbeck, S.: Internal Report BLN MT/2017/0607, Berlin, October 14, 2017Search in Google Scholar

Received: 2020-03-03
Accepted: 2021-01-13
Published Online: 2021-10-12
Published in Print: 2021-10-31

© 2021 Walter de Gruyter GmbH, Berlin/Boston, Germany

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