What Is a Plastic Valve?
A plastic valve is a type of valve made from plastic materials, such as PVC or PTFE.
While some valves made of stainless steel or cast iron may incorporate plastic components, plastic valves are entirely constructed from plastic materials.
Plastic valves are typically employed in corrosive environments where plastic is the only suitable material or in situations where metal valves are not feasible.
However, due to their resin-based construction, plastic valves have lower absolute strength compared to metal valves. Additionally, extended exposure to sunlight may result in deterioration and a loss of strength.
Uses of Plastic Valves
Plastic valves are frequently used in corrosive chemical pipelines, capitalizing on their resistance to chemical degradation. They excel in handling highly concentrated hydrochloric acid, such as 35% hydrochloric acid, and are commonly chosen when strength is not a concern.
For applications involving sulfuric acid, high concentrations may require steel galvanized pipes (SGP), but for hydrochloric acid, resin-based valves become the primary choice.
Plastic valves are also preferred when dealing with corrosive fluids in situations where various liquids are mixed. Valves made from low-elution resin can even be used in pure water pipelines without issues.
Principle of Plastic Valves
Plastic valves are primarily constructed from materials such as PVC or PTFE, imparting them with high corrosion resistance.
One significant advantage of plastic valves, in addition to their corrosion resistance, is their lightweight nature, exerting minimal stress on the piping system.
Valves made from stainless steel with PFA coating or rubber lining can be heavy and labor-intensive to install. If the coating or lining becomes damaged, it can lead to rapid corrosion in those areas.
Plastic valves, on the other hand, are lightweight and inherently corrosion-resistant, offering a significant advantage in this regard.
However, due to the characteristics of plastic materials, they may degrade when exposed to ultraviolet light. Similar to how plastics outdoors often turn white over time, PVC can gradually deteriorate and lose strength. Consequently, when PVC is used outdoors, periodic replacement may be necessary.
Additionally, being plastic, their impact resistance is lower. Therefore, careful consideration is required when using PVC in pipelines susceptible to water hammer, and adequate piping support must be ensured.