Industries that rely on storage tanks and containers most often struggle with corrosion under insulation. Although corrosion under insulation or CUI is a common phenomenon, the maintenance expenditures incurred by the industries to remedy it are still high. So what is corrosion under insulation, and how can it be prevented? Corrosion under Insulation is a collective term used for corrosion that happens due to moisture on the external surface of the insulating jacket.
Some of the most common CUI types are chloride corrosion, galvanic corrosion, and acid/alkaline corrosion. Several factors can promote the entry of moisture into the insulation and lead to corrosion. Besides this, corrosion can occur on any insulation surface and equipment that is used regularly or cyclically. Since undetected corrosion can lead to stress-corrosion crackling, tank facility operators should rely on worldwide inspection services to provide agencies familiar with various API tank assessment standards.
In this, we will discuss some storage insulation corrosion prevention techniques in detail.
The first and foremost thing to keep in mind is preventing liquid from entering into the insulation. Moisture buildup and decrease the efficiency of the insulation and eventually erode the pipe and equipment. Factors like vibration, human abuse, weather conditions can further damage the insulation.
When designing a corrosion prevention plan, here are the things you should make allowance for:
- Proper selection of insulation
- Design of the storage tanks and equipment
- Anti-corrosion paints and coatings
- Weather barriers
- Tank inspection and maintenance practices
If the tank is susceptible to spill or kept in a high humidity area, special care must be taken when selecting the insulation. Weatherproofing or coating the insulation can go a long way in preventing corrosion and such measures make the insulation chemically nonreactive and non-absorbent. You can consult tank inspection companies for an informed decision.
How to prevent Galvanic Corrosion?
Galvanic corrosion occurs when there is water or moisture intrusion in insulation. Invasion of water can be prevented through cellular insulation. Plastic and rubber insulation jackets also prevent bimetallic corrosion. Plastic and rubber insulation have fire and weather-resisting properties. Such jackets can tolerate regular abuse and effective in preventing water from entering the insulation. Plastic jackets available for commercial use are also non-corrosive.
If you use metal insulation, you can, of course, coat them with non-corrosive paints. Paints are effective in preventing cathodic and anodic reactions, which further helps the water and moisture from corroding the insulation.
How to prevent Alkaline or Acidic Corrosion?
If you are using metal jackets, you should make sure they have moisture barriers. In case the jackets are prone to corrosion, the use of plastic jackets can help prevent damage. If the piping is made of stainless steel, one should be careful about the insulation, cement, and water.
Before underground insulating pipes, they should be coated with coal-tar epoxy and nonreactive paints. Besides this, a polyethylene jacket should be used to cover the pipes before installing them underground.
Field-made joints are susceptible to CUI. Regular inspection and assessment of joints and intersections can help you keep a check on corrosion and damage.Tags: API Tank Inspection, Vessel Inspection