Magnetite formation in high temperature test facilities - an operational experience

The experimental studies and the operational experience in high temperature test facilities indicate that in a circulating system, adherent magnetite layer of about one micron thickness can be formed on carbon steel surfaces by hot-conditioning in the temperature range of 200 - 250degC in about 15 days. The magnetite layer once formed provides good protection against corrosion for extended periods even when the carbon steel surfaces are exposed to atmosphere. The exposed magnetite layer peels off under thermal shock but it gets restored fairly fast when water at appropriate temperature with requisite chemistry controls is circulated in the system. (author). 4 figs