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April 8, 2022

The key to more efficient wastewater systems

Category: Cement, Water and Wastewater

By gaining a deeper understanding of common corrosion patterns, operators of wastewater systems can choose the right surface coating to extend component life.

When components of wastewater systems corrode prematurely, the consequences can be costly. Operators may have to deal with unplanned stoppages, replace parts before the end of their reasonable lifespan, and address environmental damage caused by leaks and overflows.

Protective surface coatings for wastewater systems offer a cost-effective solution to premature corrosion by extending the life of components and reducing the risk of failure. However, the wide variety of components and materials used in wastewater management and the broad spectrum of surface treatments available have made choosing an appropriate product difficult.

A useful tool in determining what coating is needed is gaining a better understanding of common corrosion types in wastewater systems. By learning more about the various corrosion mechanisms and the forces involved, operators can select a surface coating that specifically addresses them, greatly enhancing effectiveness.

Pitting corrosion

Take the problem of pitting corrosion failures.

Pitting typically occurs on carbon steel and cast iron alloys (say within a thickener tank) when the natural oxide layer on the metallic surface is disturbed.  This causes the exposed area to become anodic (i.e. release electrons) while the covered areas remain cathodic. As the anodic region is likely to have a smaller surface area than the cathodic region, corrosion ‘pitting’ commences in the anodic region. As corrosion progresses the pit deepens, and the pH levels continue to drop.

Understanding this mechanism can inform the decision-making process when it comes to choosing a long-lasting and effective surface coating. To be effective in an area prone to pitting, a coating will need to have high tensile adhesion to resist under-film corrosion and high abrasion resistance to resist losses exposing regions that can become anodic. A suitable coating should have low permeability and be generally resistant to thermal and chemical exposure.

All corrosion types

Similar conclusions can be drawn by examining problem areas such as graphitic corrosion (common in cast iron and ductile iron), galvanic corrosion, microbiologically influenced corrosion (MIC) in metal and concrete, and acid attack in concrete.

The overall aim is to help operators avoid using inappropriate products and zero in on the right coating for each application. Chesterton’s coating experts can provide customers with further advice based on their own individual circumstances and requirements.

Proven global track record

The Chesterton® ARC Industrial Coatings range has a four-decade proven global track record of enhancing critical industrial equipment and structures. They are engineered to protect metal and concrete surfaces from the damaging effects of abrasion, erosion, and chemical attack.

One example is ARC S1HB, a single coat, low VOC barrier coating that protects both metallic and cementitious surfaces from corrosive exposures. Its high-build, edge-retentive properties ensure maximum coating coverage over hard 90° edges and corners with minimal thinning at the sharp edges. ARC S1HB is resistant to a broad spectrum of corrosive agents including H2S, hydrocarbons, wastewater flows, brackish and marine water exposures, as well as mild acid and caustic solutions.

Imatech is the Chesterton exclusive ARC coating distributor for Australia, providing innovative solutions for industrial wear protection.

Visit imatech.com.au or read more about Chesterton’s range of concrete coating solutions here 

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