Case Study: Corrosion Under Insulation (CUI) Failure in a Malaysian Refinery — Millions Lost

Corrosion Under Insulation (CUI) Failure in a Malaysian Refinery — Millions Lost

In 2021, a major petrochemical facility in Johor, Malaysia, faced a serious shutdown after a critical process pipe ruptured due to Corrosion Under Insulation (CUI). The plant lost over SGD 5 million in repair costs, safety investigations, and unplanned downtime.

As one of the most common and dangerous hidden threats in industrial insulation systems, CUI often goes undetected until it’s too late. This real incident offers valuable insights for insulation contractors and plant owners across Asia.

1. What Happened?

• A medium-pressure process line at the refinery developed an internal leak

• Root cause analysis showed external corrosion at a pipe elbow

• The insulation system (mineral wool with aluminum cladding) had trapped moisture

• Heavy rainfall and failed sealing worsened water ingress

• The insulation showed no external damage, masking the corrosion beneath

This was a textbook case of CUI — insulation that looked intact but was rotting the steel underneath.

2. How CUI Happens in Southeast Asia’s Climate

Singapore, Malaysia, and other tropical countries face:

• High humidity and rainfall exposure

• Frequent thermal cycling (heat during operation, rain during shutdowns)

• Insulation breakdown from UV, vibration, and aging

These factors make CUI risk extremely high unless insulation systems are regularly inspected and maintained.

3. Prevention Measures Recommended by Loonglobal

To avoid similar disasters, Loonglobal Engineering applies:

• Closed-cell insulation (e.g. elastomeric or Foamglas) to prevent water wicking

• Double-seal systems at elbows, flanges, and supports

• Non-metallic jacketing or stainless steel in corrosion-prone areas

• CUI monitoring tags and planned removal for inspection every 3–5 years

We also recommend infrared thermal imaging to detect cold spots or wet insulation that could indicate CUI risk.

4. Takeaways for Insulation Stakeholders

This Malaysian incident could have been prevented with:

• Better insulation design for climate exposure

• Proactive inspection and seal maintenance

• Use of CUI-resistant materials and QA/QC during installation

At Loonglobal Engineering, we prioritize durability over lowest-cost, because failure always costs more.