Abstract: Recently, leakage frequently occurred in instrument measurement nozzles in petrochemical enterprises, which is caused by the corrosion under insulation, the medium corrosion and the poor manufacturing quality of material. Some control and prevention measures, daily check strategies and maintenance points are proposed by analyzing several kinds of failure cases and corrosion mechanism of the measurement nozzles, so as to ensure the long-term and safe operation of the units.

Key words: instrument measurement nozzle, corrosion under insulation/CUI, manufacturing quality of material