Tools To Prevent CUI: Insulation system maintenance

If the pipe insulation is covered with well-designed, well-installed, and well-sealed jacketing, as discussed in the above section, then it is well protected against CUI. However, once this has been accomplished, the system must be maintained. Therefore, the next tool in the CUI prevention toolbox is insulation system maintenance.

For example, consider an insulated pipe that:

• is several decades old
• has an original insulation system of the same age;
• is located in a relatively rainy climate (something other than the U.S. desert southwest and, at the extreme, along the coast of the Gulf of Mexico);
• has been shut down for an extended period of time during the system’s life;
• is uncoated; and
• has been poorly maintained.

In this case, it is highly likely that the pipe has suffered from CUI. It would be completely unrealistic for the owner or anyone else to expect to not find CUI. In such a case, the CUI is not necessarily the fault of the insulation system design. It further is probably not the fault of the protective jacketing or the insulation material(s). The problem is that when a system has not been well maintained, water—perhaps with dissolved salts from the Gulf of Mexico spray—eventually will get beneath the jacketing between the pipe and the insulation materials, and it will lead to corrosion of the pipe.

In his article, “Is There a Cure for Corrosion Under Insulation?” (Insulation Outlook, November 2005), Mike Lettich emphasizes the necessity for effective maintenance in the battle to prevent CUI. For example, if the insulated pipes have been walked on, resulting in denting of the metal jacketing, there will be water intrusion. If the caulk along the overlapped butt joints has not been periodically replaced, it will become brittle and lose its sealing capability, and rainwater eventually will leak into the system. If caulk around the penetrations—particularly along the top sides of the pipes—has not been examined and replaced as necessary, water will intrude.

For better or worse, the world experienced a prolonged period of very low energy prices from about 1985 to about 2002, with a few, occasional short-term spikes in natural gas prices. With low energy prices, many process pipelines simply were not well maintained due to inadequate maintenance budgets. (This was not the case with all facilities, but it occurred all too often.) With a poorly installed jacketing system—and one inadequately maintained—the insulation system will simply leak rainwater, and CUI will eventually occur. All types of insulation material can be used effectively, up to their design temperatures, if water is kept out of the system. If water gets into the insulation and CUI results, to then simply put all the blame on the materials that make up the insulation system is to put the blame where it should not be placed.

Source:http://www.insulation.org/articles/article.cfm?id=IO080302