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phosphoric acid molecule

Phosphoric Acid

Also known as:

  • Orthophosphoric acid
  • Monophosphoric acid
  • Phosphoric (V) acid
The Science

Why CPVC Works Well With Phosphoric Acid

High-quality CPVC like Corzan® CPVC has a high level of chlorine on the polymer chain. This protects the CPVC from the degrading effects of highly corrosive acids commonly used by industrial plants for everything from metal treatment to the manufacture of other important industrial chemicals. Within safe operating temperatures, Corzan CPVC has excellent resistance to phosphoric acid due to its superior engineering and formulation.

CPVC resists material degradation and corrosion far better than metals, but these still can occur over time. The severity of both general degradation and localized stress cracking is often contingent on temperature, pressure, acid concentration, strain applied to the material, manufacturing quality, fabrication quality and the quality of the CPVC compound. CPVC degradation caused by hydrochloric acid comes in the form of darkening and material embrittlement.  

Temperature & Concentration

Corzan CPVC's Resistance to Phosphoric Acid

CPVC compound and product quality matter, especially as the heat and acid concentration rise. Corzan CPVC’s superior compound and quality assurance make it the premier CPVC brand, delivering excellent resistance to all concentrations of phosphoric acid within the material’s overall working range in industrial applications like acidity regulation and pharmaceutical intermediaries*.

corzan cpvc chemical resistance to phosphoric acid chart

* Corzan® Material and Piping Solutions only partners with manufacturers with a proven track record of quality and reliability. These manufacturers are carefully chosen to convert Corzan CPVC into the high-performance piping systems, ducting, sheets and lining and more that customers rely on. Always confirm any planned application is in compliance with our partner’s design guidelines.

Drawbacks of Other Materials

The Drawbacks of Other Materials Handling Phosphoric Acid

Phosphoric acid is among the top ten most common chemicals that Corzan CPVC reliably handles in industrial applications. Any material will react to phosphoric acid in different ways according to concentration levels, temperatures, pressures and nature of the material. But engineers choose Corzan CPVC for phosphoric acid due to its performance capabilities compared to metals and other plastics. 

PVDF (Polyvinylidene fluoride) and PVDF lined pipe: PVDF can be used for concentrations up to 85% but but is a significantly costlier material. It is also under extra regulatory scrutiny due to their persistent nature.

PP (polypropylene) and PP-R (polypropylene random co-polymer): While PP and PP-R can be used with phosphoric acid in concentrations up to 85%, special fusion equipment is needed. 

Stainless 316: Stainless steel is generally resistant to acidic corrosion. However, exact resistance levels will depend on the specific type of stainless steel in use, concentration levels, types of acid, and environmental temperature. Stainless steel grade 316 offer resistance to phosphoric acid at most concentrations but comes with a high material cost. 

Monel 400: Monel 400 is known for offering significant resistance to pure phosphoric acid. It is corroded at low rates of about 10 mpy for all concentrations at temperatures up to 176oF. At higher temperatures, the corrosion rates may increase considerably. 

Incoloy 825: provides outstanding corrosion resistance to pure phosphoric acid at all concentrations and temperatures up to including 85% acid.

Inconel 600:  resists phosphoric acid at room temperature.

Common Uses

Common Uses of Phosphoric Acid

  • Fertilizers (up to 80% of all phosphoric acid)
  • Rust removal
  • Food additive (acidulant for the beverage industry)
  • Acidity regulator in foods like jams and processed meats
  • Additive for the formulation of personal care items like cleansers, bath products, fragrances, hair care products and dyes, nail products, makeup and other skincare products
  • Intermediate in pharmaceuticals manufacturing

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For long-term system reliability, it is critical to choose a material that resists corrosion. Corzan CPVC effectively stands up to most acids, bases and salts and is innately resistant to corrosive chemicals, including the 10 commonly used chemicals that can degrade and reduce the service life of many metals.