B. Improving Plant Reliability through Corrosion Monitoring

B. Improving Plant Reliability through Corrosion Monitoring
Corrosion attacks can reduce equipment performance and lead to unexpected failures and
plant shut downs. Corrosion attack of process equipments may be external or internal.
External attack is by ambient environment whereas internal attack is caused by process fluid
handled inside.
Corrosion monitoring is an essential input in Residual Life Assessment and Aging
Management Programme.
Corrosion monitoring techniques are;
- Methods that indirectly measure parameters related to corrosion and inter corrosion
behavior from some model of corrosion process, e.g. electrochemical potential, pH and
temperature.
- Methods that directly measure corrosion behavior, e.g., Non-destructive Inspection,
Material Test Coupons, Galvanic Currents etc.
Corrosion Monitoring Techniques:
Direct Measurements
• Non Destructive Inspection (NDI)
• Electrical Resistance (ER) Probes
• Material Test Coupons
• Galvanic Currents
• Cyclic Potentiodynamic Polarization (CPP)
• Linear Polarization Resistance
• Electro Chemical Noise (EN)
• Electrochemical Impedance Spectroscopy (EIS)
Indirect Measurements
• Potential
• Biological Count
• Hydrogen
• pH
• Temperature
• Conductivity
• Specific Ions
Periodic assessment is the most common method of corrosion monitoring and can help to:
• Evaluate materials performance under specific service conditions
• Aid in proper material selection
• Evaluate and control the production process
• Provide necessary data for Residential Life Assessment