Corrosion Resistance

Unlike metallic alternatives, Corzan® CPVC innately resists corrosion and scaling, protecting you from costly remediation, inefficiencies and danger.

What are Corrosion and Scaling?

Corrosion is the deterioration of material – primarily metal – resulting from various reactions that occur between the material and its surrounding environment. There are several types of corrosion:

• Internal Corrosion – Generally caused by the medium the piping system is transporting, any fluid with pH levels outside of neutral (+/-7) may cause metals to corrode, and ions within acidic (pH < 7) and alkali (pH > 7) fluids and saline solutions attack specific metal elements at the molecular level and eat away at the material. The attack accelerates in the presence of dissolved oxygen and higher temperatures. High-purity water systems can also cause corrosion in metallic pipes, as it will try to strip away metallic ions.
• Pitting Corrosion – This type of internal corrosion causes localized, small pits or cavities to form due to film damage. This is a highly penetrative, very dangerous form of corrosion that can cause extreme failures with little warning.
• Crevice Corrosion – This is a type of internal corrosion in which deterioration occurs at any crevices, as where two different materials meet. Stagnant liquid in the crevices accelerates this form of corrosion.
• Flow-Accelerated Corrosion (FAC) – FAC is caused by turbulent flows common with the typical higher pressures, temperatures and fluid velocities in industrial applications.
• Under-Deposit Corrosion (UDC) – UDC occurs when localized pitting and corrosion forms underneath existing solids, which then deposits in boiler tubes.
• Galvanic Corrosion – Also known as bimetallic corrosion, galvanic corrosion is an electrochemical reaction where one metal corrodes another due to electrolyte exchanges when the dissimilar materials meet. This is a common form of corrosion when different metals (a cathode and an anode) are joined.
• Microbiologically Influenced Corrosion (MIC) – MIC is caused by the metabolic activity of microorganisms that live in the biofilms on the inside surface of pipes. MIC can introduce harmful byproducts into a piping system that will induce some of the types of corrosion defined above.
• Ambient or External Corrosion – This is any form of corrosion caused by the external environment in which the system exists. For example, systems may corrode from the outside to the interior in environments that are close to large bodies of water and salt water, as with ships and offshore platforms. Ambient corrosion is also more likely to occur in cold environments where insulation is applied to the outside of metal piping to protect it from freezing. Improperly properly designed and installed insulation often allows moisture in but not out, resulting in corrosion under insulation (CUI) in insulated metal piping.