How to Eliminate Corrosion Under Insulation in Food and Beverage Plants

Consistent Process Heat Retention Minimizes Energy Costs

In traditional insulation systems, thick mineral wool or other insulating materials are banded around assets and covered with exterior metal cladding to minimize moisture penetration. Such systems may be applied to storage tanks, steam piping, boilers, sterilizers and other equipment to keep the contents inside at elevated temperatures. Doing so minimizes the amount of additional heating the plant needs to apply to those assets to keep thick food materials like molasses or pumpkin puree flowing or to maintain food safety standards for ingredients as they make their way through a plant before being mixed or packaged.

Exterior insulation systems offer highly effective thermal performance, especially when brand new. However, despite their protective cladding, they are prone to moisture infiltration, which can diminish their thermal performance. With just 10% water by volume present in the mineral wool, the insulation loses up to 85% of its R-value. Once moisture penetrates the cladding and saturates the mineral wool underneath, the insulation may never dry out. Therefore, the thermal performance loss is permanent, forcing the plant to increase its heating costs to maintain temperatures.

TICs don’t face the same thermal performance loss related to moisture penetration. The closed-cell structure of the coating film helps to minimize the amount of moisture the material can absorb. Any moisture taken up can then dissipate from the coating within 24 hours via heating and evaporation, ensuring consistent thermal performance.

That thermal performance is surprisingly high, considering TICs are only applied at about half to three quarters of an inch thick compared to inches-thick insulation systems. In fact, that thickness of a TIC like Heat-Flex® Advanced Energy Barrier (AEB) from Sherwin-Williams Protective & Marine can help assets maintain operating temperatures up to 350°F (177°C), with excursions to 400°F (204°C). The coating can retain a minimum target of 70% of that heat energy with just the material applied to the exterior of an asset with no other insulation added on top.

A high insulation particle content within its dried coating film enables Heat-Flex AEB’s insulating capability. The particles couple with entrapped air present in the film, providing an effective insulator to slow the transfer of heat energy through the coating. The coated asset therefore retains more heat, and with TICs remaining at the same level of insulating capacity throughout their service lives, owners won’t need to increase process heat over time, helping them reduce costs.

Eliminating CUI Yields Notable Cost Savings

Process heating savings can be significant over time when using TICs in place of traditional insulation systems. But the biggest cost savings come from the ability to eliminate CUI when using coatings. CUI is a leading cause of costly plant shutdowns because it is hidden under physical materials and therefore difficult to identify. There may not be any visible rust stains on piping or storage tanks even though corrosion is well underway. Therefore, CUI might not be caught until the facility’s next scheduled inspection period. Even then, technicians may not catch it, as they typically only remove portions of cladding and insulation – not the entire insulation system – to inspect the metal substrate below. Any spot that’s missed will continue corroding and may not hold up until the next inspection cycle, causing leaks or worse.

TICs are able to literally eliminate CUI because they literally eliminate the insulation under which CUI could take hold. With no insulation on top, there’s nothing to absorb moisture and contaminants and then sit in constant contact with the metal substrate in a heated environment. The zone underneath insulation that’s highly amenable to corrosion forming – and is essentially a catalyst for it – disappears once the insulation is no longer there.

With insulation removed and CUI eliminated, plants no longer need to engage in the periodic CUI inspection protocols noted above. That means no more time spent cutting access panels in insulation systems, removing sections of mineral wool, and observing the substrate underneath or performing ultrasonic metal thickness testing before putting everything back in place. Instead, the only inspections plants will need to perform are visible scans for atmospheric corrosion, which are far easier to conduct, take less time and are less expensive.

Choosing TICs Reduces Material Use for Environmental Savings

Further savings enabled by using TICs instead of traditional insulation systems fall on the side of resource reductions, giving plant owners an opportunity to reduce their environmental footprints. A large volume of physical materials is required to install a physical insulation system, including batts of mineral wool, wiring, pins, banding and the exterior metal cladding that covers these materials.

When using a TIC instead, the only materials required are the coatings themselves. That enables plants to forgo the hard and environmental costs of manufacturing, shipping and storing the insulation system materials, which would take significant amounts of water, raw materials and energy to manufacture otherwise. Every batt, wire, band and piece of cladding saved therefore represents environmental savings.

Naturally, the TIC that will be used in place of an insulation system carries an environmental footprint from its production to its application to its replacement. However, that footprint is far smaller than what’s realized with a physical insulation system, which will likely include a coating layer itself. So, the environmental costs associated with preparing an asset’s metal surface for coating and then applying a coating on top is typically present whether using a TIC or an exterior insulation system. Therefore, the additional materials associated with the exterior insulation system add significantly to the environmental impact.

Additional environmental savings are recognized when using TICs because the coated assets have longer service lives before any steel needs to be replaced, if at all. Some steel replacements are an eventual likelihood when using traditional insulation systems due to serious pitting corrosion or metal loss that may take hold under the systems. Without CUI being possible when using TICs, any steel repair needs are highly unlikely.

Thinking back to the consistent thermal efficiency TICs offer compared to traditional insulation systems, even more environmental savings become evident. Because plants do not have to increase commodity heating over time when using TICs, they will spend less energy and therefore reduce their associated emissions. Plants using traditional systems may experience increased heating and therefore higher environmental costs over time.