Abstract: The heat exchange tube bundle is the key component of ORV (Open Rack Vaporizer) equipment. The LNG in the heat exchange tube bundle exchanges heat with the seawater flowing in the shape of water curtain on the outer surface to complete the gasification process of LNG. This paper analyzes the damage mechanism of the heat exchange tube bundle, and provides a method for calculating the optimal replacement cycle of heat exchange tube bundles based on the principle of minimizing the total cost incurred by heat exchange tube bundle failure and periodic planned shutdown for tube bundle replacement. The results show that the main factors of damage and failure of heat exchange tube bundle are electrochemical corrosion, microbial corrosion, seawater quality, seawater erosion, cracking and so forth. Taking an LNG terminal as an example, the optimal replacement cycle of ORV heat exchange tube bundle at the terminal is obtained byadopting the calculation method described in the paper. The results of this study can provide a theoretical basis for the maintenance and replacement of ORV heat exchange tube bundles.

Key words: ORV heat exchange tube bundle, heat exchange, damage mechanism, optimal replacement cycle