Customers from a wide range of industries require a variety of valves to increase operations. Valves are available in a variety of materials to suit any application. Carbon steel, PVC, cast iron, stainless steel and ductile iron are some of these substances. In this article, we will examine two of them: ductile iron and cast steel. The "ductile iron vs. cast steel valve material" debate has existed for decades, as not most people are familiar with these differences.
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Fortunately, comparing valves made of ductile iron and cast steel is simple, as there are only a few significant differences between the two materials. We will describe the qualities of each material and then weigh the advantages and disadvantages of each. By the conclusion of this blog post, the reader will become a valve expert!
Ductile iron is a relatively new iron alloy formed from endogenous graphite. This provides high ductility to the fabric, which means it will not crack when bent. The thermal limit is slightly lower than that of cast iron, although it remains relatively high at F (730°C). Ductile iron valves are also available in pressure grades 150 and 300. 150 grade ductile iron maintains a seal at normal ambient temperatures up to 250 psi. 300 grade can withstand pressures up to 640 psi.
Ductile iron has high strength and stiffness, structural rigidity, and ultimate tensile strength. Because ductile iron does not break when folded, it is better suited for application operations than cast iron. Ductile iron is a durable material for use in piping, joints and valves.
Design teams will also be interested to note that the Poisson's ratio for ductile iron is typically considered to be 0.275. ratio limits are as important as the design professional. The ratio limit for the 0.2% ultimate stretch ratio for the ferritic level (60-40-18) is typically 0.71. For the austenitic level, the same ratio is typically 0.56 (80-55-06).
Ductile iron has excellent structural integrity and can withstand high temperatures without damage. This is due to the ductility of the raw material, which makes them much less likely to bend and twist. During this time, rust is also attracted to ductile iron.
Ductile iron is used in more specialized industrial applications to improve fracture toughness:.
● Drums made of cables
● Frames
● Gearboxes
● Pumps
One disadvantage is cost. Due to its more complex chemical composition, ductile iron is usually more expensive than cast iron. Nevertheless, if your project requires a more robust material, you may need to invest a little extra.
Advantages of ductile iron.
● Improved castability.
● Cost savings
● Improved vibration damping
● Improved corrosion rates
● Excellent compression yield toughness
Cast steel valves are made by a process called "casting". This process involves melting steel and then forming it into the desired shape. Advanced cast steel valves are quite affordable in terms of effectiveness, longevity, quality and fatigue strength. For example, cast steel taps are widely used in the petrochemical industry, power stations, waste treatment units, treatment plants, rail lines and other applications.
Depending on the application, cast steel valves may be made of high-grade steel or metal alloys. Because they are created using molds, you can simply design these valves to have complex forms or intricate features. They can be produced in any size, and a single valve can contain multiple components.
Design flexibility: Because cast steel valves consist of molten material, they can be easily molded into any size or shape. You can also increase the complexity of the design and create complex functional parts for the valve.
Versatility: Cast steel valves offer a wider range of metal compositions. Cast steel valves can be made from a variety of metal alloys. You can specify precise parameters, such as improved corrosion resistance, by using the appropriate metal composition.
Reduced machining: Cast steel valves can be manufactured without extensive machining. This equates to lower processing costs and faster turnaround times.
Cast steel valves are more widely used than forged steel valves. This is due to the lower difficulty and cost of casting compared to forging. Replacement components and valve service are more readily available. Spare parts and valve service are more readily available.
Space-saving design: Cast steel valves are curved and have rounded sides. This makes them easy to install, especially in tight spaces and pipelines.
Casting generates a lot of waste. Some material is lost as the metal is converted to fluid. The fluid is then modified as it enters and leaves the mold. A portion of the core material is wasted at each stage.
The solidification process of cast steel valves sometimes leads to microscopic impurities such as cracks and crevices in the valve. This can lead to poor mechanical quality that can only be restored by time-consuming and expensive weld repairs.
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Heat treatment can change the composition of the cast steel valve part when it is welded in one piece. As a result, the valve creeps more and becomes less ductile. Thorough inspections must be performed to ensure that the valve's robustness and creep tolerances have not deteriorated after welding.
Because cast steel valves are tested to a lower standard than forged steel valves, extra care must be taken when obtaining these valves. Specialized industrial valve manufacturers, such as KXC, ensure that each cast steel valve has the necessary certifications and testing, although this is not always the case.
Ductile iron chemistry typically contains 3.0% to 3.9% carbon, while cast steel typically contains 0.08% to 0.60% carbon. Therefore, the carbon concentration of ductile iron is higher than that of cast steel.
Ductile iron and cast steel have similar tensile strengths; however, ductile iron has a higher tensile strength of 40k psi, while cast steel has a maximum yield strength of only 36k pounds per square inch. In terms of equivalent grades, ductile iron has greater yield toughness. As a result, ductile iron can replace most cast steel and, in some cases, forged steel in the production of crank propellers and gears.
While the elongation of ductile iron is 18%, the maximum elongation of cast steel is 25%. Therefore, cast steel has greater elongation and superior impact properties. The AKV of cast steel is 30J.
Because cast steel has better welding characteristics than ductile iron, welding alternatives are often used in production and do not degrade mechanical quality. However, ductile iron is a good material for making equipment bases because of its high impact absorption.
Although iron foundries may add certain elements to ductile iron, alloyed cast steel is available in a wider variety and classification and therefore can meet the needs of a wide range of unique applications.
So there you have it. As you can see this is not a case of ductile iron vs. cast steel valves. One is not necessarily superior to the other. It all depends on what you want to do with it!
KXC offers valves in a variety of sizes, even some that are hard to find! So if you're looking for anything to fit your requirements, be sure to contact the experts here!
Though there is a list of advantages and disadvantages to the Ductile Iron Pipe, it is still a well-suited choice for many projects. Their main advantages are strength and durability, corrosion resistance, flexibility and impact resistance, high flow capacity, and environmental friendliness.
In addition to these advantages, ductile iron pipes also have disadvantages. Expensive cost, high weight, complex installation, and challenging maintenance are examples of the disadvantages you may encounter. Moreover, you can choose the material of the pipes used in your projects differently based on some key features. These materials include ductile iron, cast iron, steel, prestressed reinforced concrete, and PVC plastic. Here, you can learn more about them to make the most appropriate choice.
Ductile iron pipes offer many advantages. Although there are many advantages and disadvantages to ductile iron pipes, the advantages outweigh the disadvantages. Referring to ASCE, these benefits make DI pipes a popular choice for many applications.
The durability of ductile iron pipes might be their most known advantage. Ductile iron combines iron, silicon, carbon, and a small amount of magnesium. This combination gives it a unique molecular structure, which leads to improved strength. The ability to endure high pressure makes them suitable and proper for so many applications. This strength is not only due to the chemical and physical properties of iron, but it is also a result of the centrifugal casting method in manufacturing. This is especially beneficial in gas and water distribution systems. Using appropriate pipe installation methods and relying on ductile iron pipe strength and durability makes this material a long-lasting solution for your projects.
Corrosion resistance in water pipelines is crucial. Among all the advantages and disadvantages of ductile iron pipes, corrosion resistance is highlighted in the pipe material comparison. They are highly resistant to corrosion, which makes them a perfect choice for achieving a long lifespan for ductile iron pipes.
The cost of ductile iron pipe maintenance and repair is also significantly reduced. This feature helps the pipes remain functional throughout their service life.
The mechanical properties of ductile iron prove to us that this material is less brittle than other types of iron. Thus, ductile iron pipes are more flexible and show more resistance to impact. This way, the potential for cracking or fracture is reduced, which makes these pipes durable. Ductile iron pipes can also withstand sudden pressure due to their impact resistance. Furthermore, this feature is especially beneficial for applications in areas subject to earthquakes or seismic activities. This way, sudden movements of the earth would never lead to the rupture of the whole structure.
Ductile iron pipes provide a high flow capacity due to their smooth interior surface. This ensures efficient fluid transportation. The high flow capacity that ductile iron pipes provide is beneficial, especially in large-scale industrial projects and applications. This feature contributes to the popularity of ductile iron pipes in many industries since it offers cost savings, enhanced efficiency, and system reliability.
Among all the advantages and disadvantages of ductile iron pipes that could be possibly mentioned, being eco-friendly is the most crucial one in today’s life. As various industries have destroyed the environment tremendously, being environmentally friendly is a significant factor to consider, which ductile iron pipes guarantee. This is because they are made from recycled materials. These pipes have lower friction, which leads to saving energy, so it reduces pumping costs and makes them eco-friendly. This energy efficiency causes lower greenhouse gas emissions, leaving a smaller environmental footprint.
As you can see, ductile iron pipes have advantages and disadvantages. Though the advantages are numerous, according to Xylem, there are still a few disadvantages. Considering these factors might help when deciding the best option for specific applications.
A primary disadvantage of ductile iron pipes is their high initial cost, especially compared to other materials. These higher expenses extend to many steps, such as the purchase price, transportation, installation, and maintenance of ductile iron pipes. This certainly is a highlighted factor when it comes to projects set with low budgets or even large-scale projects that need a huge amount of these materials.
Ductile iron pipes are considerably heavier than other alternatives. Comparing ductile iron to PVC or HDPE perfectly proves this point. This higher weight causes higher transportation and installation costs. Also, labor requirements are increased due to the heavy weight of these pipes. In addition to all the above factors, the heavy weight can be a safety hazard for workers handling these heavy materials. That is why safety protocols are a must on job sites.
Since ductile iron pipes have heavier weights and specific material properties, more specialized equipment and expertise are required for installation when working with ductile iron pipes. This also raises the project’s overall expenses. For instance, the need for heavy lifting machinery raises the costs of the project significantly. As the project gets larger, the management of the logistics of transporting and installing these heavy pipes gets more critical.
This is where the advantages and disadvantages of ductile iron pipes cross. Although they have good corrosion resistance, they are not fully immune to corrosion. Harsh environmental conditions can weaken the protection barrier to ensure these pipes’ corrosion resistance. Exposure to certain chemicals or elements running in the pipes increases the potential for corrosion over time. This compromises the structural integrity of the pipes, which could result in leaks and failures.
In addition to the challenging installation due to the weight and material properties, maintaining and repairing these pipes can also be quite a challenge over time. The processes of maintenance and repair have their own complexities and additional costs. Maintaining and repairing ductile iron pipes requires specialized tools and expertise. The result is increased expenses and downtime, especially compared to other materials used for manufacturing pipes.
Several different materials can be used to make pipes. Each has its own specifications, advantages, and disadvantages. Each has some highlighted features. These features can be used to make decisions regarding specific requirements your project might have. Some of the primary features are listed below.
Here, some of the material’s most decision-making features are compared in a table so that you can make the right choice based on your needs.
Specification Ductile Iron Cast Iron Steel Pipe Prestressed Reinforced Concrete PVC Plastic Strength and Durability High High High High Low Corrosion Resistance Good Moderate Moderate Good High Flexibility and Impact Resistance High Low Moderate Moderate Low Weight Heavy Heavy Moderate Heavy Lightweight Installation Complexity Moderate Moderate Low to Moderate High Low Maintenance Requirements Low High Moderate Low Low Environmental Friendliness High Moderate Moderate High Moderate Cost-Effectiveness Moderate Low Moderate Low High Temperature Resistance High Moderate High Moderate Low Load-Bearing Capacity High High High High Low Pipe Diameter Availability Wide range Wide range Wide range Wide range Wide range Flow Efficiency High Moderate Moderate High HighAs with all materials, ductile iron pipes have several advantages and disadvantages. The most important thing to consider when choosing the right material for you is to compare all the features. In a specific condition and for each project, some of these advantages and disadvantages outweigh others. The key to making wise choices is to choose a material with advantages and disadvantages that match our needs. You can contact us for more information and help.
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