New Modeling Approach for Predicting Corrosion Under Insulation

CORROSION UNDER INSULATION · BIM · INSPECTION

Corrosion under insulation (CUI) is difficult to manage because the insulation system can hide the very conditions inspectors need to find.

Building information modeling (BIM) cannot replace inspection or directly confirm that corrosion is present. But when asset, environmental, design, and inspection information are incorporated into a digital model, BIM can help teams visualize CUI risk and prioritize where closer inspection may be warranted.

Why Corrosion Under Insulation Matters

Insulation is widely used on piping and equipment for thermal control, personnel protection, process efficiency, condensation control, and other operational needs. However, an insulation system can also obscure the condition of the substrate beneath it.

If water or other contaminants penetrate the insulation system and remain in contact with susceptible metal, conditions may develop that support corrosion. Because the affected surface is hidden, deterioration may progress without obvious external evidence.

Depending on the asset, corrosion can contribute to wall loss, leaks, loss of containment, repair costs, production impacts, contamination concerns, or other integrity consequences.

How CUI Develops

CUI can develop when moisture penetrates an insulation system and reaches the underlying metal. Water may enter through damaged weather barriers, failed seals, penetrations, joints, poor detailing, condensation, washdown, weather exposure, or other pathways.

If that moisture remains trapped, drying may be slow. Contaminants such as chlorides can further influence corrosion conditions in some environments.

The actual risk varies with factors such as substrate material, operating temperature, insulation type and condition, weatherproofing, exposure, contaminants, geometry, water ingress, and time.

Why CUI Inspection Is Challenging

The scale of industrial piping and insulated equipment makes universal inspection impractical. Removing insulation everywhere would be disruptive, costly, and often unnecessary.

Visual inspection of the insulation system can identify obvious damage or water-entry points, but external appearance alone may not reveal the actual condition of the metal beneath the insulation.

For that reason, CUI programs often rely on risk-based screening and targeted inspection rather than treating every insulated component as equally likely to contain corrosion.

Using Risk Factors to Prioritize Inspection

CUI susceptibility can be influenced by a combination of design, environmental, operating, and condition factors. These factors can be used to identify areas where additional inspection attention may be justified.

From Predictive Analysis to Risk-Based Inspection

If relevant CUI risk factors are documented, they can be combined to help rank areas for inspection. A location exposed to repeated water ingress, aggressive contaminants, susceptible materials, and unfavorable operating conditions may warrant greater attention than a comparable component without those factors.

This does not prove corrosion exists. Instead, it helps inspection teams make more informed decisions about where to focus resources and where more detailed examination may provide the greatest value.

The Role of BIM in CUI Management

BIM provides a digital representation of physical assets and can associate individual components with additional information. In a CUI program, that creates an opportunity to connect the physical location of insulated piping or equipment with relevant integrity data.

Instead of relying on a separate spreadsheet or inspection report to understand where risk factors are concentrated, teams can use the model as a visual interface for organizing and interpreting that information.

Visualizing Inspection Priority

One possible approach is to represent risk or inspection priority using colors or other visual markers within the model. Higher-priority areas could be highlighted so inspectors can quickly identify locations that warrant closer attention.

The specific color scheme is less important than the methodology behind it. A useful model should be based on defined criteria and reliable information rather than a subjective visual rating alone.

A Practical BIM-Supported CUI Workflow

BIM Can Help Make CUI Inspection More Focused

The challenge with CUI is not simply finding corrosion. It is identifying where hidden deterioration is most likely or most consequential across a potentially enormous population of insulated assets.

BIM can support that process by bringing asset location, operating conditions, environmental information, inspection history, and risk data into a visual framework. Used well, it can help inspection teams make more focused decisions about where to look next.