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August 13, 2019
A Range of Valve Materials for Different Operating Environments
A valve, also known as a regulator, is a mechanical device that controls the flow and pressure of liquids, gases and slurries within a system, and is used in many different forms. Valves can be grouped by several factors, including their control mechanism and application. They come in many sizes, styles and uses, and suit a variety of different operations.
There are three main valve applications: regulating (controlling) flow — the speed and volume of the substance moving through the system; stopping and starting flow — for systems that don't need flow control; and preventing backflow (check valves), which control the direction of flow. The valve material must suit the fluid expected to enter the pipe. It does not always have to resist corrosion from the working fluid, but where the purity of the fluid is critical, the material in contact with it should be corrosion-resistant. The rate of corrosion determines the valve's service life. We supply many brands, such as auma thailand and Ebro Valves.
Valves can be made from many materials, both metallic and non-metallic. Metals are used for the valve body and internal components such as the stem, ball and disk, while non-metallic options are used for gaskets, stem-packing seals and seats. Metallic materials are based mainly on iron and other (non-ferrous) metals, while non-metallic materials are based mainly on rubber and plastic. Choosing materials can be complex; most valve makers have the experience to find a solution that fits the application. Each material has properties suited to different flow conditions — for example continuous flow or static flow.
The most popular material is carbon steel, because it withstands high heat, is easy to obtain and is inexpensive. Other factors to consider when selecting a valve material are the operating environment, service life (e.g. maintenance) and the substance (e.g. whether it is a gas or a corrosive liquid). Bronze/brass, cast iron, forged iron, cast metal and stainless steel are the basic materials commonly used to make gate, globe, ball and check valves.
Bronze suits complex castings thanks to its high wear and corrosion resistance, is easy to form, and is well suited to making valves for low/medium-pressure use.
Stainless steel is strong and resistant to both corrosion and high temperatures. It covers a very wide range of uses, from the petrochemical industry to general plant systems. However, it costs more than carbon steel.
Cast iron is often used for piping in oil drilling, refineries and petrochemical plants, because it can handle a wide range of operating temperatures and pressures.
Grey cast iron is generally used for relatively low-pressure, low-temperature operations. It can also be used in many areas, from kitchenware to artwork, thanks to its ability to handle a range of temperatures and pressures and its durability comparable to copper. Forged iron is therefore often used in steam, water, gas and oil piping systems.
Coating cast iron is useful for stopping water from turning rusty red, and is also suitable for drinking-water supply pipes.
