Corrosion under insulation is the cause of many of the process industry’s most pressing problems. These problems include forced shutdowns, lost productions, early repair and replacements, and other safety and environmental consequences – resulting in billion dollars worth of capital loss and additional money which could be spent productively elsewhere.
The US Chemical Safety Board (2008) reported that “The highest incidence of reported leaks in refining and chemical industries are due to CUI and not to internal process corrosion.” This means that there is a higher chance of piping leaks due to localized, external corrosion within the piping insulation in comparison to the inner piping. Industry data suggests that 60% of pipe leaks are caused by CUI– with 81% of pipe leaks occur within pipes smaller than 4 inches. With the cost of CUI is 40%-60% of the maintenance budget.
It is critical to note that corrosion under insulation is responsible for up to 60% of incidents, and the amount to which CUI has cost industries is an estimation of $276 billion in 2005.
Besides the cost of correcting CUI, this would lead to questions of why is it a growing problem within the industry? And what are the challenges that businesses face with CUI?
1. Challenging to detect
Generally, corrosion-under-insulation tends to remain undetected until the insulation and cladding are removed for inspection, or when leaks occur- such visually, this cannot be detected during routine inspection.
2. No published performance data for new coating and insulation innovations
CUI failure patterns can generally take 10 to 20 years for it to emerge on facilities and nurtures confidence to reduce inspection costs significantly.
3. Difficult to confidently predict CUI
This type of corrosion is often difficult to predict. It is noted as even more challenging without the removal of insulation. Such, there is no sure-fire way to be able to provide a confident prediction or forecast on when CUI will occur with an asset.
4. Removal of insulation is still considered as the most reliable method
It is still widely believed that the removal of the asset’s insulation or visual inspection is still the best way to detect CUI as the entire surface is inspected. However, this can be very expensive as it requires plant shutdown, insulation would need to be replaced, it is quite time consuming, and relatively intrusive.
5. NII techniques may not be reliable and as cost-effective
Non-Intrusive inspection allows for the examination of assets with little interruption to the processes. Despite this, however, several Non-Intrusive Inspection techniques and technologies may not be considered as reliable or cost-effective as the removal of the insulation.
So what is the solution?
A Risk-Based Inspection (RBI) approach is used to identify highly vulnerable equipment that may be subjected to CUI, manage critical inspections, and generate an inspection plan to mitigate risks. This is integrated when developing your asset’s CUI inspection plan.