Comparison of PVC Valves with Conventional Metal Valves

PVC Ball Valves
PVC Ball Valves | Source

Valves are broadly classified into PVC valves and metal valves based on the material of construction. While both metal and PVC valves have their own set of benefits and limitations, it is important to understand the basic properties of the materials used prior to using them in an application. PVC valves or plastic valves are constructed mainly from polyvinyl chloride, with valve components made from polypropylene, ABS, and FRPP materials. Metal valves have a rigid structure and are made from cast iron, carbon steel, or stainless steel.

PVC valves are widely known for their lightweight construction, low cost, and corrosion resistance. They are tough, non-conductive, and ideal for piping systems that handle chemicals, corrosive acids, and hard water. Even if the most corrosion resistant metal valve is used, it is still susceptible to electrolytic or galvanic corrosion. Hence, PVC valves are highly preferred over conventional metal valves.

Metal valves remain durable over a wide range of temperature and pressure conditions, crucial for high temperature/pressure environments. Plastic valves can remain stable only up to a temperature of 250ºF and a pressure of 230 psi. Although 70% of the applications fall under this range, extremely high temperature and pressure environments require metal valves.

PVC valves are widely used in chemical industries as they show high resistance to oxidizing chemicals, caustics, halogens, solvents and acid wastes. Waterparks, aquariums, and residential plumbing applications also use PVC valves. Valves made from FRPP (Fire-Retardant Polypropylene) are used in hazardous environments.

Metal valves made from gunmetal are widely used to control the flow of oil, gas, fluidized solids, and water. They are used extensively in thermal power stations, distilleries, and paper mills. Cast iron butterfly valves are preferred choices in thermal, nuclear, and municipal corporations. With capabilities to handle pressure of up to 300 psi, bronze check valves are in high demand in thermal plants, pumping stations, mines, and hydroelectric projects.

The following is a comparison between PVC valves and conventional metal valves:

 
PVC VALVES
METAL VALVES
Material of Construction
CPVC, UPVC, PP, PE, FRPP, PVC, Acetal, ABS, PVDF
Carbon Steel, Stainless Steel, Bronze, Cast Iron, Ductile Iron, Hastelloy, Monel, Inconel, Brass
Types
PVC Gate Valves; PVC Ball Valves; PVC Diaphragm Valves; PVC Butterfly Valves; PVC Globe Valves; PVC Check Valves; Universal Line Valves; Straight Supply Valves; Angle Supply Valves; Washer Hose Valves; Angle Valves; Sill Cocks
Gate Valves; Ball Valves; Diaphragm Valves; Butterfly Valves; Glove Valves; Check Valves; Angle Valves; Plug and Key Valves; Drainable Valves
Advantages
Lightweight; Chemical and Corrosion Resistant; Low Cost; Eco-Friendly; Toughness; Non-Conductive; Ideal for Hardwater
Withstand High Temperature and High Pressure; Durability; Can handle fluidized solids, gas, oil, and water; Long Service Life
Disadvantages
Cannot be used to transport steam and compressed air; Not suitable for high pressure, high temperature environments; Thermal Expansion
Heavy; Electrically Conductive; Expensive; Corrosive
PVC Valves vs Conventional Metal Valves

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