Corrosion inside process equipment is not a gradual nuisance. In many chemical applications, it can accelerate quickly under changing process conditions and create risks that traditional inspection cycles struggle to detect.
In a recent on-demand webinar, Corrosion in the Chemical Industry: an IIoT Asset Monitoring Approach, Emerson’s Shane White, Business Development Manager, Wireless and Integrity Solutions, outlined how a condition-based, data-driven approach can improve visibility, reduce risk, and support more reliable operations.
Why It Matters
Inline corrosion is driven by aggressive chemistry, temperature, pressure, flow effects, and phase changes that can rapidly shift operating conditions. The financial impact goes well beyond replacement cost, with unplanned downtime, environmental consequences, and safety risks often representing the largest exposure.
In many cases, corrosion can progress faster than inspection intervals allow, particularly during process upsets. A more continuous view of asset condition helps engineers move from reacting to failures toward anticipating them.
Key Takeaways
- Corrosion in chemical processes is driven by multiple interacting factors, not just material degradation
- High-risk processes such as acid production, chlor-alkali, and high-temperature hydrogen service require targeted monitoring strategies
- Manual inspection alone often misses rapid corrosion events between inspection intervals
- Combining leading indicators like process conditions with lagging indicators like wall thickness improves visibility
- Industrial Internet of Things (IIoT) monitoring enables scalable, condition-based corrosion management
Understanding Corrosion Beyond “Rust”
As Shane explains, inline corrosion is not simply rust forming on steel surfaces. It is the result of electrochemical and chemical reactions within pipes and vessels, intensified by the process environment.
Several drivers commonly interact:
- Aggressive chemistry including strong acids, bases, and corrosive gases
- Temperature and pressure that increase reaction rates or gas solubility
- Flow dynamics such as turbulence removing protective films or stagnation promoting deposits
- Phase changes where condensation concentrates corrosive species
These factors make corrosion behavior highly variable. A system that appears stable can quickly become aggressive when process conditions shift, sometimes leading to rapid material loss.
High-Risk Processes and Failure Mechanisms
There are several chemical processes in which corrosion poses an elevated risk. While each process differs, they share a common pattern: specific conditions can trigger accelerated damage.
For example, in sulfuric acid production, temperature and turbulence can break down protective films, leading to rapid wall loss. In phosphoric acid systems, solid particles create erosion corrosion, removing protective layers while chemical attack continues. Chlor-alkali operations must manage both wet chlorine corrosion and stress corrosion cracking from caustic soda.
Other examples include:
- Hydrogen-related damage such as high-temperature hydrogen attack in ammonia production
- Localized corrosion in heat exchangers and dead legs
- Under-deposit corrosion where fouling creates oxygen-depleted environments
Across these scenarios, one point stands out: corrosion is rarely uniform. It concentrates in predictable weak points such as elbows, welds, interfaces, and stagnant regions.
The Limits of Periodic Inspection
Traditional inspection strategies rely on non-destructive testing techniques performed at scheduled intervals. While important, this approach has inherent gaps.
As Shane notes, inspections may occur every three to five years, but a process upset can cause significant damage in weeks or even days.
This mismatch creates risk:
- Corrosion rates can change rapidly between inspections
- Localized damage may go undetected
- Unplanned shutdowns can occur without warning
The financial and operational consequences are significant. Unplanned downtime alone can cost hundreds of thousands to millions of dollars per day, often accounting for the largest share of corrosion-related losses. These limitations are driving a shift toward continuous monitoring.
Linking Process Conditions to Asset Health
A central theme in Shane’s presentation is the link between process conditions and corrosion outcomes.
He distinguishes between:
- Lagging indicators, such as wall thickness measurements, which show damage after it occurs
- Leading indicators, such as pH, temperature, or moisture, which signal conditions that may cause corrosion
Individually, each provides partial insight. Together, they create a more complete picture. For example, a spike in moisture could correlate with an increased wall-loss rate in downstream piping. This allows operators to intervene before significant damage develops.
This cause-and-effect visibility is a key advantage of Industrial Internet of Things approaches. By integrating multiple data streams, engineers can better understand not just where corrosion occurs, but also why.
Enabling Continuous Monitoring with IIoT Technologies
Shane describes how Industrial Internet of Things (IIoT) solutions provide “eyes inside the pipe” with continuous data collection. Platforms such as Emerson’s Plantweb Insight integrate sensor data and analytics tools to present asset health in a consolidated view.
Key capabilities include:
- Correlating process data with corrosion measurements
- Providing alerts and visualization of asset health
- Scaling from small deployments to broader monitoring strategies
- Integrating with existing infrastructure and workflows
Field devices play a critical role. Wireless ultrasonic thickness transmitters, such as the Rosemount™ Wireless ET210 Corrosion and Erosion Transmitter, measure wall thickness without interrupting operations, enabling non-intrusive monitoring in hazardous environments. These devices support continuous measurement, helping engineers detect corrosion trends early and plan maintenance more effectively.
