Apr 03, 2015

Samples of carbon steel tubes were removed from the radiant section of a fired heater after 40 years operation at 950oF to 1000oF (510oC to 538oC) tube metal temperature. The tubes exhibited significant microstructural degradation in the form of advanced pearlite decomposition and graphitization (graphite nodules). However, no evidence of linking of graphite nodules was observed. This paper highlights the results of an API 579 Fitness for Service analysis using the MPC Omega creep methodology to help show that the tubes have significant remaining creep strength and are suitable for continued service, contrary to the results of an API 530 analysis1,2.

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