Customers from all kinds of industries need valves of all varieties for their high-demand processes. Valves are available in a huge number of materials for any application imaginable. A few of these materials are PVC, carbon steel, stainless steel, cast iron, and ductile iron. In this post we will focus on two of those materials: ductile iron and cast iron. The argument of "ductile vs. cast iron valves" has been going on for decades, as not everyone knows the differences.
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Luckily, comparing valves made of ductile iron and cast iron is simple, as these materials have just a few major differences. We will outline properties of both materials and then go through the pros and cons of each. By the end of this blog post, you will be an iron expert!
Cast iron (also known as gray iron) is a type of metal that has been in use for hundreds of years. It is an alloy made from 96%-98% iron, 2%-4% carbon, and small amounts of silicone. It has impressive temperature tolerance, with some cast iron capable of handling temperatures over F (C). When it comes to pressure, cast iron's strength depends on its pressure class. The two most common are class 125 and class 250. At less extreme temperatures, class 125 cast iron flange is rated for pressures between 150 and 200 psi. Class 250 cast iron is a bit tougher, with pressure ratings from 300 to 500 psi. These pressures can vary by end type.
Cast iron is strong and will usually go undamaged even after going through intense vibrations. The main drawback of cast iron valves is that they are not very ductile at all. Virtually any bending will cause cast iron to crack and become useless. One great quality of cast iron is that it is not very expensive. As far as metals go, cast iron is usually the most economical option, which makes it a solid alternative for people on a budget.
The second material we're looking at is ductile iron. Ductile iron is a more modern iron alloy that is made with nodule-shaped graphite. This gives the material excellent ductility, so it will not necessarily break when bent. The temperature limit is a bit lower than cast iron, but it is still quite high at F (730C). When it comes to pressure, ductile iron valves also use pressure classes: 150 and 300. At standard outdoor temperatures, class 150 ductile iron keeps a seal up to 250 psi. Class 300 can stand up to pressures as high as 640 psi.
Ductile iron has excellent corrosion resistance, tensile strength, and yield strength. Unlike cast iron, ductile iron does not break when it is bent, so it is more suited for high demand applications. Ductile iron is a strong and reliable material for pipes, fittings, and valves. One drawback is price. Ductile iron is typically more expensive than cast iron due to its more complicated chemical makeup. If your application requires a tougher material, however, you may need to spend a little more.
Now that we've looked at both options individually, we will compare and contrast ductile and cast iron valves. Hopefully, this will help you decide which is best for you! We will compare these materials on durability, ease of installation, and price, so you can learn the most important details. For some more technical differences, check out this helpful article.
There you have it! Now you know that this is not an "ductile vs. cast iron valves" kind of issue. One is not always better than the other. It all depends on what you are using it for!
Not all valves are built the same and there's good reason for that. Knowing a few basic facts about the different materials will ultimately have long-term effects on your application's capabilities. Cast iron, ductile iron, bronze and stainless steel are all similar metals but what stands each of these apart? We'll assist you in choosing the best metal solution for your everyday valve application needs.
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Cast iron ' a metal made from mostly iron with small amounts of carbon and silicone ' is known for its tolerance to extreme temperatures. It can handle temperatures over 2,100 degrees Fahrenheit. It is a very strong metal and can usually go undamaged through situations of intense vibration; however, cast iron is extremely rigid and has a low resistance to bending. Almost any bending will cause the material to fracture or break completely. A big advantage to cast iron is the cost. It is a relatively inexpensive metal and a very economical and useful option for most situations.
Ductile iron, as its very name suggests, is more flexible than cast iron. It is an iron alloy made with nodule-shaped graphite crating a metal that has a little more room to bend without breaking or cracking. With the ability to flex, however, comes a lower overall temperature tolerance than cast iron and a slightly higher cost.
Valves built from ductile iron have excellent corrosion resistance and superb strength, making it a great choice for applications in which a tougher material is needed and in conditions where weathering is likely. Here at Flomatic all of our ductile iron valves are epoxy coated to protect the valves from long term erosion and corrosion in many different fields of application.
The use of bronze in plumbing systems dates back to the Roman Empire. Made primarily from copper and tin, this metal is both strong and malleable. It does not crack as easily as iron as it has high ductility. Bronze is also known for its high resistance to corrosion even against harsher fluids and those similar to seawater. However, the nature of the alloy causes it to have a somewhat rough and porous surface which can leave the material susceptible to pitting and degradation over time if not properly maintained.
It is important to note that consumers should seek out valves with the lowest lead content. Make sure if you're picking out a bronze valve for potable water, you're choosing a valve that is ANSI/NSF 372 & ANSI/NSF 61 certified. These certifications mean it meets the minimum lead requirements for safe and healthy drinking water.
Stainless steel has become a very popular valve material for many reasons. Valves made from this metal have exceptionally high oxidation and corrosion resistance and extreme durability, making a product that lasts a long time. Stainless steel valves do not rust, even if placed in areas of high moisture or directly in water. This property makes them a great choice for coastal regions where saltwater corrosion may be a concern.
The smooth metal is easily cleaned, and a popular choice for food and beverage applications. Stainless steel has good heat resistance; however, it is not ideal for extreme high-temperature applications. A potential downside of stainless-steel valves is that they're very expensive. However, with price, comes high-quality.
Using the information provided above, think about your scenario and the conditions in which the valve will be used. Will it be outdoors? In severe temperature? Will this metal be susceptible to movement and vibration? Once you determine the extremes, you're easily able to choose the appropriate metal for your application.