The carburization performance of plasma powder welded overlay ethylene pyrolysis furnace tubes has been evaluated in laboratory studies and plant trials. The results indicate that the PPW layer serves as a barrier to carburization of the tube base alloy by inhibiting carbon diffusion across the PPW/base material interface. The findings have a significant implication for the realisation of improved furnace performance and extended tube life. The carburization properties of the PPW overlayed tube have been quantified using a Larson-Miller approach and the benefits with respect to both extended tube life and/or increased tube metal temperature capacity determined. Tube life times of up to 3 times the life of conventional tubes have been predicted.

Subject
Iron nickel chromium alloys, Carburization, Materials, Pyrolysis, Diffusion, Tubes, Molybdenum alloys, Oxide layers, Furnaces, Metals, Ethylene, Carbon, Alloys
Keywords:
PPW, ethylene, furnace tubes, carburization, remaining life
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2005
Association for Materials Protection and Performance (AMPP)
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