March 2014

Corrosion Under Insulation

This month Rilco Manufacturing is participating in the NACE Corrosion Exhibition in San Antonio, Texas. We are highlighting our latest innovation in pipe supports, as well as our various pipe support products.

In honor of the tradeshow our March Newsletter features the topic of Corrosion Under Insulation.

What is CUI?

CUI, or corrosion under insulation, is a type of corrosion that is localized at the interface of a metal surface and the insulation utilized for that surface.

Why is it Significant?

Exxon Mobil Chemical conducted a study that indicated that in the refining and chemical industries the highest occurrences of leaks were due to CUI rather than process corrosion. The study also revealed that between 40% and 60% of piping maintenance costs stem from CUI. Essentially, this means that enormous costs are allocated toward repairing major equipment outages, unexpected maintenance costs, and excess unplanned downtime. CUI is one of the costliest problems facing industries such as Oil & Gas and petrochemical.

corrosion on pipe

What are the Causes?

CUI is caused by various factors that are particularly common in the pipeline construction industry. Water, Oxygen, and warm temperatures combined with a piping surface covered by insulation that prevents evaporation and enables the buildup of moisture will quickly lead to CUI. Furthermore, traditional thermal insulation materials such as, calcium silicate, contain chlorides. If exposed to moisture, the chlorides could be released into a moisture layer on the pipe’s surface and result in stress corrosion cracking.

What are the Methods of Detecting CUI?

Detecting CUI can be an immense challenge considering that the corrosion is hidden beneath the piping insulation. Inspections for CUI are also not typically conducted regularly enough due to the high cost of removing the insulation, inspecting, and then re-insulating. There are various other detection methods such as conventional radiography, pulsed eddy current, etc. but they all pose similar high cost re-insulation issues.

If CUI has been a persistent problem with your projects contact a Rilco representative who can inform you on the ways in which our latest technology in pipe supports will virtually eliminate the possibility of CUI along with the significant costs associated with it.