Hidden Secrets of Corrosion Under Insulation

Diagram of typical inspection port.
Diagram of typical inspection port.

Sept. 21-23, 2016, 8:00am-4:00pm

Holiday Inn, 1000 Busse Road, Elk Grove Village, IL

Corrosion Under Insulation is a complex and invisible form of corrosion most readily seen in insulated pipes, but also in insulated tanks.

“The corrosive environment under insulation can be fantastically severe, complex and difficult to mitigate,” said Warren Brand, owner of Chicago Corrosion Group, a vendor-neutral corrosion mitigation consulting firm. “What’s worse,” he continued, “is that it’s invisible.”

And almost all insulated pipes and tanks are at varying degrees of risk.

“CUI is perhaps the most complex, aggressive and confusing corrosion mechanism I, as a coating professional, face,” said Brand. “Lining a swimming pool or a sulfuric acid tank is a cakewalk to addressing CUI, particularly once corrosion has taken hold.”

Some of the challenges in understanding how to mitigate and identify CUI include:

Temperature ranges from subzero to > 800 F.

Temperature cycling.

Freeze thaw conditions.

Damp insulation and wet-dry cycling.

Inability to visually inspect.

Complexity in coating pipes, flanges, fittings, supports, etc.

Poor or incompatible paints and coatings on the pipe unable to prevent corrosion.

And, perhaps the most challenging is a simple lack of data.

CUI is a relatively new phenomenon borne of the oil crises of the 1970s when the price of oil sored. Companies were grasping at ways to save money and realized they were wasting billions of dollars a year in wasted heating and cooling costs, primarily on piping. So, they started insulating. However, the instant owners started insulating their pipes, corrosion rates skyrocketed. Pipes that otherwise would have exhibited little to no external corrosion for decades were now corroding to perforation in less than a year, primarily due to wet insulation, but for other reasons as well.

Duplicating these environments in a lab and attempting to gather accelerated testing data is like trying to grab smoke — due to the complexity of the variables involved.

One insidious variable, for example, almost impossible to capture in a lab is the type of insulation and the environment at a typical petrochemical facility. Absorbent insulation (which ideally should typically not be used) acts exactly like a sponge. And, like a sponge, will absorb not only rainwater and humidity, but also whatever chemicals and contaminants are in the surrounding atmosphere.

For example, let’s say we have a pipe that cycles between ambient and 250F. (By the way, if the pipe stayed at 280F, corrosion would not be an issue because no liquid moisture could stay in contact with the pipe). As the insulation absorbs salts from the air and dries out, the salt concentration on the pipe wall will increase over time, increasing the rate of corrosion on any exposed steel.

Just within the past decade or so, owners are recognizing the severity of the issue and starting to develop strategies to prevent CUI from taking place in the first place, through intelligent design prior to construction, as well as repair and mitigation in situ.

A case in point is the development and use of inspection ports in insulation jacketing to provide access to the base metal of the pipe to evaluate its condition.

There are a variety of organic, inorganic and metallic — in the form of thermal sprayed aluminum and other alloys — insulations which are able to provide barrier protection to the steel, even upwards of 800F. But the insulation is of great concern in terms of type and design. Then there are other technologies, such as stand-off insulation.

During my constant battle with corrosion, I was fortunate enough to speak with some of the legends in the fight against CUI and there is, just now, beginning to be consensus on how to solve this complex problem.

In our continuing fight against corrosion, I will be working with one of these legends, Peter Bock, in offering a three-day class on CUI September 21st – 23rd. Peter is a petrochemical coatings consultant and CUI expert with nearly 40 years of experience in our field. He is past president of the NACE New Orleans section, is NACE CIP 3 certified and all around good egg.

The class will be held at The Holiday Inn in Elk Grove Village, Ill., at a cost of $1,850.00.

“The class is unique in North America,” said Brand. “Pete is honestly one of the top people in the industry. You’ll have his undivided attention for three days, and there will be hands-on activities in addition to lecture.”

A link to the Syllabus can be found here: https://www.dropbox.com/s/f3r0d1iet9atxb3/CUI%20Syllabus%202016.pdf?dl=0 — and please contact [email protected] for additional information.

Our goal is to continue to shed light and clarity on the challenges surrounding all issues pertaining to corrosion.