Easy to use Analyzers for Reliable Corrosion Measurements

Corrosion is a natural process that results in the gradual destruction of metals through a chemical reaction with their environment. The World Corrosion Organization estimates that the total annual cost of corrosion can be as high as 3 –3.5 % of a country’s GDP. This unavoidable deterioration of material is a costly problem and billions of dollars are spent each year to control, monitor and prevent corrosion processes.

Reliable Corrosion Measurements via Electrochemistry

Over the past three decades, several methods have been introduced to measure and monitor corrosion. While many of these traditional methods, such as weight loss or spray test analysis, are quick and cost-effective, they can only offer a qualitative overview of the process. In comparison, electrochemistry techniques are accurate, reproducible and often the only method to measure corrosion rates on a quantitative basis. Electrochemistry has not only made it easy and direct to measure the parameters governing the corrosion processes but has also helped greatly in the overall development of the novel corrosion-resistant films and corrosion inhibitors.

Depending on the nature of the application, different electrochemical techniques are needed to determine specific parameters of interest. Metrohm offers fully customized corrosion analyzers to evaluate corrosion parameters for specific ASTM methods.

Real-Time Corrosion Measurements in Process Operations

The collection of samples and process data, including corrosion prevention and control indicators, is critical for efficient plant management. In order to prevent unscheduled plant shutdowns, process engineers rely on colleagues in the lab to pinpoint corrosion problems. One of the most effective ways to bridge laboratory analyses to the process environment is to employ real-time analysis monitoring. Metrohm offers tailored process analyzers to monitor corrosion products, corrosion inducing ions, corrosion inhibitor performance, pH and more. Multiparameter analysis in real-time is the most dependable way to identify and correct corrosion culprits while ensuring continuous improvement and process optimization.

Corrosion parameters of interest and the relevant ASTM methods are summarized in the table below. 
TechnologyParameters of InterestASTM Reference MethodsApplications
Electrochemistry• Polarization resistance (Rp)
• Corrosion rate (mm/year)
• Corrosion current
• Corrosion potential
• ASTM G102-89 (2015)
• ASTM G59-97 (2014)
DC techniques
• Linear sweep voltammetry
• Tafel slope analysis
• Potentio-dynamic polarization (LPR)
• Film resistance & conductivity
• Charge-transfer resistance
• Solution resistance
• Polarization resistance
• ASTM G59-97 (2014)
• ASTM G106-89 (2015)
AC techniques
• Electrochemical impedance analysis (EIS)
• Redox kinetics
• Pit initiation
• Crevice progression
• Hydrogen resistance
• Surface morphology
• ASTM G150-99 (2010)
• ASTM G148-97 (2003)
• ASTM G100-89 (2015)
• ASTM G61-86 (2014)
• ASTM F746-04 (2014)
• ASTM F2129-15
Chrono & other techniques
• Electrochemical noise (ECN)
• Critical pitting technique (CPT)
• Hydrogen permeation study
• Cyclic polarization
• Hydrodynamic linear sweep
Process Analytics• Conductivity
• pH
• ASTM D5128-14
• ASTM D6569-14
Direct measurement techniques
• Conductivity
• pH
• Corrosion Inducing Ions
• Corrosion Products
• ASTM D2791-19Titration techniques
• Argentometric
• Colorimetric
• Complexometric
• Thermometric
• Corrosion Inducing Ions
• Corrosion Products
• Corrosion Inhibitors
• ASTM D5996-16
• ASTM D6504-11
Ion Chromatography Techniques
• Conductivity
• UV-Vis

The process analytics ASTM methods above were developed specifically for on-line measurements, but there are many more ASTM methods developed for lab measurements which can be designed into process analyzers.