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By: Sinikka Freidhof on Sep 5, 2022 1:00:00 AM
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Why is Chemical Resistance Crucial in Desalination?

Understanding Corzan® CPVC’s performance in some of industrial processing’s most corrosive environments

In industrial processes like desalination, frequent use of ferric chloride, sodium bisulfite and sulfuric acid can limit piping system service life and incur frequent repair costs. 

Corzan CPVC possesses exceptional resistance to a wide range of corrosive substances and environments, including those mentioned above. Let’s look at CPVC’s performance in these environments in more detail and why they are so essential to desalination.

Can CPVC be used in desalination? 

One of the main advantages of Corzan CPVC is its excellent resistance to corrosive environments. Engineers have replaced steel systems with CPVC and in doing so have extended equipment service life, reduced maintenance and  minimised life-cycle costs.


Chemical Resistance in metal vs CPVC

Oxidation is one of the main threats to metal pipework, as it can cause pitting  & crevice corrosion, which can only be remedied with costly repairs. 

Corzan CPVC has oxidation resistance engineered into the molecular structure of CPVC for best in class corrosion resistance, against ferric chloride, sulfuric acid, sodium bisulfite and more, which is good news for desalination plants.


Ferric Chloride

Ferric chloride is essential to the reverse osmosis process that makes desalination possible. It is instrumental in removing organic matter from the water supply, however in doing so, it can put major pressure on pipework. 

Ferric chloride is a strong oxidizing agent and causes significant pitting and crevice corrosion in metallic pipework. Over time, leaks cause irreversible damage to infrastructure and productivity, at which point the only remedy is piping system replacement.

Corzan CPVC is inherently resistant to oxidizing agents and has best in class resistance to Ferric Chloride. 


Sulfuric Acid

Sulfuric acid is a popular method of regulating the pH level of feed water in desalination, however it is a highly corrosive and hazardous substance. Even at lower concentrations, it can corrode carbon steel.

For low and mid range concentrations of sulfuric acid, Corzan CPVC is recommended as a cost effective alternative to alloys and fluoropolymers. 


Sodium Bisulfite

Sodium bisulfite is used in desalination to dechlorinate seawater, typically at a concentration over 37%. As such, it is another highly corrosive process. Many plastic pipes require a specialised UV coating to cope with the high concentration of sodium bisulfite, incurring additional infrastructure costs. 

Corzan CPVC has exceptional sodium bisulfite resistance, particularly against non-metallic alternatives. Its inherent heat resistance maintains system performance even at temperatures above 40℃.


Plastic or Steel?

In the hazardous, corrosive environment of the desalination plant, engineers need to be mindful of the efficiency of day to day operations, but also the longevity of the system in place. 

Corzan CPVC is specifically designed for chemical resistance, but also financial stability in our industry:

  • No reliance on ancillary anti-corrosion agents
  • Lower repair and maintenance costs
  • Lower life cycle costs

To learn more about the chemical resistance of CPVC, along with a complete guide to specifying and using Corzan CPVC in desalination, watch our free webinar.