| Abstract: | Laboratory studies on corrosion of unalloyed steel in cooling waters Corrosion tests were carried out in recycle apparatures to prepare cooling-water treatment. The corrosion behaviour of unalloyed steel St 38b-2 in dependence on m-value of water was tested. The corrosion-inhibiting effect of sodium polyphosphate, zinc sulfate, 1-hydroxy-1,1-diphosphonic acid (HEDP) and the trisodium salt of HEDP and polyacrylate and their combinations in water with m-value 1.0–1.5 mmole per litre was tested in comparison with unalloyed steel. The corrosion rate increases strongly below a m-value of 2.2 mmol per litre. Sodium polyphosphate, sodium polyphosphate/zinc sulfate and zinc sulfate-polyacrylate show good protection features in water with m-value 1.0–1.5 mmole per litre. The trisodium salt of HEDP has an insufficient effect. |
