What Manufacturers Need You to Know About Corrosion Under Insulation
In today’s times, information is available as fast as we can open a search engine on our mobile device, and social media environments have enabled news to travel across the globe in an instant. Immediate access to information has allowed our world economy to evolve to the point where seemingly every new problem that arises in our daily life can quickly be answered with a product solution.
We’ve grown so accustomed to instant product solutions that we now expect them. However, there are some things that just cannot be resolved that easily. Corrosion under insulation (CUI) is one of them. Specifiers are always on the hunt for the miracle product to avoid the single largest threat to a mechanical piping system.
Conversely, manufacturers are relentlessly pursuing the ideal product that engineers and facility owners will universally accept as the best solution to prevent or inhibit corrosion. Their efforts have generated many great options to consider: protective coatings, insulation with corrosion inhibitors, hydrophobic or closed-cell insulation materials, zero-perm rated vapor barriers, etc.
In my career, I’ve represented various manufacturers and had opportunity to promote all of the aforementioned protectors against CUI. I want to share three important things that all manufacturers of mechanical insulation products desperately want you to know and accept about CUI.
1. It’s not the insulation’s fault.
Insulation materials don’t cause corrosion. If you are a young engineer whose predecessor taught you never to allow one insulation or another because it “causes corrosion”, forget that you ever learned that, and question everything else he or she taught you.
CUI is the result of a reaction between three distinct components: water, oxygen and steel. Insulation is not one of them. The chemical composition of an insulation material may affect the corrosion rate (minimally), but it is not part of the root problem. Water is the enemy and the only element that can be separated from the other two.
Also, don’t forget why your system design includes insulation: to inhibit the the transfer of thermal energy or sound waves between your mechanical system and its surrounding environment. Some insulations may aid in separating the water from the pipe, but that is not their primary purpose.
2. CUI cannot be prevented by product selection.
Depending on the characteristics of the application and the environmental forces acting on the system, one product or combination of products will often do more to inhibit CUI than the rest. Yet, a perfect product doesn’t exist that eliminates the threat of CUI entirely. More importantly, it never will.
If you are a specifier being held accountable for the negative effects of CUI, don’t feel you need to take the blame too easily. Chances are that your original spec was driven by the goal to provide the necessary thermal efficiencies at the best value to the owner, as it should be. You probably also anticipated external risks of water and moisture penetration and made every reasonable effort to minimize them.
Building or facility owners are the ultimate customer in a project’s life-cycle. Sure, the customer is always right. But in the case of CUI, the customer also must take some responsibility. Corrosion doesn’t happen overnight. When it’s significant, owners should take full responsibility. Corrosion takes years to reach the level of catastrophic failure.
I once read an article about a large oil refinery that inspected a tank 25 years after it was installed and insulated. They couldn’t believe the accumulated corrosion and concluded that the insulation was the primary source of the problem. The only problem I could confirm for certain was that they waited 25 years to inspect the insulation.
3. Threats of CUI need to be mitigated, not prevented.
Of course, engineers need to be strategic in selecting products and designing systems to void off water and moisture. However, if piping is exposed to precipitation or a cold system is drawing water vapor to the pipe’s surface, corrosion is inevitable. It will happen eventually. The only way to minimize the ongoing risk of CUI is to manage it through a scheduled inspection program.
It is easier today than it has ever been before. There are manufacturers that now produce inspection ports an engineer can strategically add to their design in sections of piping where ingress water might be expected to pool. The small investment in these ports saves so much time and money compared to ripping off jacketing and replacing it.
Strategic product selection and system design is the foundation for reducing your CUI risk. An ongoing maintenance program is the only way to guarantee it doesn’t get out of hand.
Design engineers can do their part to educate their clients on the importance of a CUI mitigation program. Facility maintenance managers can develop an inspection schedule that coincides with their level of risk.
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