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Difference Between Cast Steel Valves and Forged Steel Valves

Posted on: December 24th, 2021

Generally, valves are mechanical devices that are used to control the flow and pressure within a system or process. They are essential components of a piping system that easily conveys liquids, gases, vapors, slurries, etc. Common types of valves are often used for domestic purposes. However, industrial valves are built to control various systems and processes. Most utilities which include water, oil, and gas, would not be able to function without heavy-duty, high-strength, industrial valves. Knowing the importance and specifications of various types of valves we get to know their different types, features, and usability.

What are Valves?

Valves are an essential part of all industrial units and systems. Still, they remain the most neglected part. This is because of the fact that they are silent performers. However, we feel their presence more when they face a malfunction or breakdown. Industrial valves serve the purpose of regulating the flow of the medium through the channels and pipelines, sometimes isolating certain areas of the pipeline and sometimes checking the system integrity of a unit, and various other functions. Different types of valves are used depending upon applications. This is the reason why industrial valves need to be of the maximum quality, leak-proof, efficient, and durable.

There had been this argument since the ages between cast steel and forged valves that have been going on for ages. For a very long time, cast steel valves have dominated industrial space as they were cost-efficient, quick-to-manufacture, and very high-quality valves that performed well in different industries. But since forged valves were introduced to the market the landscape and market dynamics were changed, as Forged steel valves promised increased strength, durability, and better performance. They were also a great option for high-temperature and high-pressure applications. Hence the debate is still ongoing today.

What is Forging?

Forging is a type of process that uses metal forming machinery that presses metal billet, making it deform, in order to obtain mechanical properties, shapes, and sizes. Forging is a common forming process that is most commonly utilized in machinery. Forging can eliminate cast loose and welding holes inside a metal. The mechanical properties of forging are more excellent than castings.

Based on temperature, forging can be classified into two major categories that are; cold forging and hot forging. Normally, cold forging is conducted to progress under room temperature while hot forging is conducted under temperature which is higher than the recrystallization temperature of the metal. The forging, whose temperature is lesser than recrystallization is known as warm forging.

What is Casting?

Casting is a process that is very much similar to injection molding, as molten liquid metal is injected into prepared mold. It forms a casting after being cooled. Based on this technique, casting can be classified few generalized categories that are:

  • Sand casting

This is the most common type of casting method that is used to make cast steel valves. In this method, a pattern that had already been molded for the valve is fitted to the bottom of the sandboxes. In order to capture the impression, these boxes are then filled with casting sand. The casting sand is then pressed firmly into the molds. Finally, the sandboxes are then turned upside down, and the molded patterns are removed, leaving an impression behind. Later on, the molten metal is poured into it which takes the shape of the impression left.

  • Investment casting

Investment casting is a process that is generally used to manufacture smaller and more precise components of cast steel valves. During this process, the first mold is made using hard wax, lost wax, lost foam, or any sort of similar material. This wax mold is then dipped in wet ceramic slurry until the time it becomes really thick. As soon as it dries, the wax is melted and the ceramic mold is left behind.

  • Other types of castings are:

    • shell mold casting
    • cavity less casting
    • low-pressure casting
    • gravity casting
    • pressure casting

Castings of the valve mean that the components including the body, bonnet, and hand wheel are cast. Casting is essentially used to manufacture components having large sizes for cost savings. However, forging is used to manufacturer smaller sizes valves.

Cast steel valves can be made from high-quality steel or metal alloys depending upon the nature and requirement of the application. Since the cast steel valves are made through molds, one can easily customize these valves easily in order to make complex shapes or complex details. As they can be made in any size, and a single valve can have various different components.

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