The Power of Monitoring in Corrosion Management

Corrosion is one of the most significant challenges faced by the oil and gas industry, and effective monitoring is key to maintaining the integrity of critical assets. While mitigation strategies are essential in combating the effects of corrosion, monitoring serves as the eyes and ears of any integrity management program. It provides the data and insights required to predict, measure, and address corrosion before it becomes a serious issue.

Let’s break down some of the primary monitoring techniques used to manage both internal and external corrosion, highlighting their functions, importance, and how they empower operators to stay proactive.

Internal Corrosion Monitoring

Internal corrosion occurs within pipelines, tanks, and process equipment due to the interaction between transported fluids and the materials of construction. Here are some of the most widely used techniques for monitoring internal corrosion:

1. Flow and Process Condition Monitoring: Monitoring the flow and process conditions, such as pressure, temperature, and chemical composition, helps operators predict where and when corrosion or erosion might occur. Theoretical calculations, such as corrosion rate models, use these variables to estimate the likelihood of damage, helping to prevent failures before they happen.
2. Probes and Coupons:

• Corrosion Probes are devices placed directly into the fluid stream to measure corrosion rates in real-time. They provide valuable insights into the current condition of the system and help validate theoretical models.

• Corrosion Coupons are physical pieces of metal inserted into the system, exposed to the same conditions as the pipeline or equipment. By retrieving and analyzing these coupons periodically, operators can directly measure the impact of corrosion over time.

Together, these tools allow operators to track corrosion trends, refine mitigation strategies, and ensure that the systems in place are effective.

External Corrosion Monitoring

External corrosion occurs on the outer surfaces of buried or exposed pipelines and assets, primarily due to environmental factors such as soil conditions, moisture, and temperature. Effective monitoring techniques for external corrosion include:

1. Cathodic Protection (CP): CP systems are designed to prevent corrosion by applying a protective electrical current to the pipeline or asset. Monitoring CP systems involves measuring potential differences across the system to ensure proper protection levels. This is critical for maintaining the long-term integrity of buried or submerged assets.
2. Over-the-Line Coating Surveys: Coating is the first line of defense against external corrosion. Over-the-line coating surveys assess the condition of protective coatings on pipelines, identifying areas of damage or deterioration. Common survey methods include:

• Direct Current Voltage Gradient (DCVG): Detects coating defects by measuring voltage gradients in the soil above the pipeline.
• Close Interval Surveys (CIS): Identifies areas where cathodic protection may be inadequate.

These surveys provide actionable data that helps operators prioritize repair and maintenance efforts.

3. External Corrosion Damage Assessments (ECDA): ECDA is a structured process that uses indirect inspection tools, such as electromagnetic surveys, combined with historical data to assess the condition of external surfaces. This method provides a detailed understanding of potential corrosion risks and helps guide proactive maintenance decisions.

Why Monitoring Matters

While mitigation techniques like chemical treatment and maintenance pigging are critical, monitoring ensures that these strategies are performing as intended. A robust monitoring program helps operators:

• Validate Mitigation Effectiveness: By comparing theoretical predictions with real-world data from probes, coupons, and surveys.
• Identify Emerging Risks: Early detection of changes in flow, process conditions, or external environments allows operators to respond before damage occurs.
• Optimize Resources: Monitoring provides the data needed to focus efforts where they are most needed, ensuring cost-effective management of corrosion risks.
• Enhance Safety and Compliance: Proactively monitoring both internal and external corrosion ensures that operators meet regulatory requirements while protecting their teams, assets, and the environment.