Toshio Fukuzuka

Corrosion problems and their preventions of MSF desalination plant constructed with titanium tube

Abstract Titanium heat transfer tubes have an excellent corrosion resistance in sea water and they are gradually beginning to be used in MSF plants. However, there have also been occasional reports that there is a possibility of crevice corrosion and hydrogen absorption occurring the titanium tubes of a badly designed plant. In this paper, our investigation of some corrosion problems in the MSF plant such as crevice corrosion of titanium tube, galvanic corrosion of copper alloy tube-plate equipped with titanium tubes and hydrogen absorption of titanium tubes were summarized. In addition, PdO/TiO 2 coating and special Fe-9%Ni alloy sacrificial anode were proposed as prevention methods against the above corrosion.

Corrosion resistance of titanium in MSF desalination plant

Abstract An experimental study on crevice corrosion and hydrogen absorption of titanium was carried out in deaerated neutral NaCl solutions similar to those in Multi-Stage Flash (MSF) evaporation desalination plant. Results obtained are as follows. 1. Titanium was subjected to crevice corrosion above 80°C in neutral deaerated 6% NaCl solutions but FdO/TiO 2 coated titanium was not subjected. 2. Titanium did not normally pick up hydrogen except when it came in contact with another metal in neutral deaerated NaCl solutions. However, in special cases, titanium picked up hydrogen when it came in contact with iron or zinc.

Application of surface air oxidizing to prevent hydrogen embrittlement of titanium in the chemical plant

Effects of surface treatment of titanium on hydrogen absorption were investigated. Surface-treated titanium specimens prepared by polishing, anodizing, and air oxidizing were immersed in 0.5 to 6 percent hydrochloric acid(HCI) solutions at a temperature range of 70 to 250°C. After immersion, the weight loss, hydrogen content, and oxide film thickness of three specimens were measured. As a result, it became clear that anodizing did not reduce hydrogen absorption of titanium because the titanium oxide film formed by anodizing had dissolved after a short period in dilute HCI solution; however, the air-oxidized specimen was stable in this solution for a long time, and therefore hydrogen absorption of titanium was prevented. These laboratory test results correspond to the results of field tests conducted in hot molten urea and mineral acid solution at high temperatures.