When using titanium heat exchangers, it is essential to pay attention to the operating environment (case study)

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When using titanium heat exchangers, it is essential to pay attention to the operating environment (case study). Incident: The tube bundles in the heating chamber of a certain brine evaporator were made of titanium alloy. Just ten months after it was put into operation, dozens of pipes cracked and perforated. The brine inside the pipe contains approximately 280 g/L of sodium chloride, has a pH of 5.5–6.5, and a temperature of 115–135°C. Analysis: Titanium exhibits excellent corrosion resistance in the atmosphere, seawater, and natural water due to its strong passivation ability. Titanium can be used in dilute hydrochloric acid at room temperature (below 5%). Similarly, titanium and titanium alloys also exhibit excellent corrosion resistance to wet chlorine gas and chloride solutions. However, in neutral chloride solutions, titanium and its alloys do not suffer from corrosion or hydrogen absorption unless the temperature is below 11°C. The steam temperature between the tubes in the heating chamber is 127–147°C, while the temperature of the brine inside the tubes is 115–135°C. Therefore, when titanium alloy tubes operate in areas where corrosion occurs, damage is inevitable.