Abstract
With a view to preventing scale from adhering to the heating surface of a brine preheater, we carried out a fundamental study concerning the possible effects of a minute quantity of sodium hexametaphosphate added to sea water or brine, on the corrosion of mild steel and copper. We obtained the following results from the above study:
1. As to effects of temperatures, an anti-corrosion effect was recognized within the range of 25-100°C when a minute quantity (30 p.p.m.) of sodium hexametaphosphate was added in case of mild steel. In case of copper, however, the effect was less, and the corrosion was even promoted in the sea water of temperatures ranging from 25°C to 50°C.
2. As to effects of the quantity of sodium hexametaphosphate, the agent proved effective in every quantity within the range of 2-200 p.p.m. in case of mild steel. In case of copper, however, it was effective only when over 30p.p.m. of the agent was added to sea water or when over 15 ppm to brine.
3. It was found that the proper quantity of sodium hexametaphosphate effective to the anticorrosion did not coincide with that effective to the anti-scaling.
