Cast Iron, Ductile Iron, Bronze and Stainless Steel Valves

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

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

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.

Bronze

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

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.

What do these terms all mean?

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.

And of course, never be afraid to ask the experts. With over 85 years of industrial experience in the valve market, Flomatic knows valves inside and out and we are happy to guide you to the right product for the right application.

As an alternative to steel, man developed ductile iron in . While cast steel contains less than 0.3% carbon, the amount of carbon in cast iron and ductile iron is at least 3%. Ductile iron has many advantages over ordinary cast iron, which makes it widely used in the manufacture of valves. LIWEI introduces you the characteristics of gate valves and why ductile iron is so famous.

Within ductile iron, the graphite flakes are changed into tiny spheres by a special treatment. This improved sphericity allows for superior physical properties of ductile iron compared to cast iron and steel. It is this spherical microstructure of carbon that gives ductile iron better ductility and impact resistance, whereas the flake form inside cast iron results in cast iron without ductility. The spherical structure inside the ductile iron also eliminates the cracking that can occur with the flake graphite inside the cast iron after the pressure-loaded parts of the ductile iron have been subjected to the ferritization annealing cycle.

In microscopic photographs of ductile iron, cracks can be seen to march to the graphite spheres and then terminate. In the ductile iron industry, these graphite spheres are called "crack terminators" because of their ability to prevent fracture.

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Compared to cast iron, ductile iron has a definite strength advantage. The tensile strength of ductile iron is 60k, compared to 31k for cast iron, and the yield strength of ductile iron is 40k, while cast iron does not exhibit yield strength and eventually fractures. The strength-to-cost ratio of ductile iron is far superior to cast iron.

The strength of ductile iron is comparable to the strength of cast steel. Ductile iron has a higher yield strength and exceeds the corrosion and oxidation resistance of cast steel in most municipal applications such as: water, salt water, steam, etc. Due to its spheroidal graphite microstructure, ductile iron is superior to cast steel in its ability to damp vibrations and is therefore more conducive to stress reduction. You can find more details and specifications in LIWEI, and we also have check valves for sale.

Gate Valves

The improved gate valve has significant advantages such as light switch, reliable seal, good elastic memory and long service life. It can be widely used in water, sewage, construction, petroleum, chemical, food, medicine, light textile, electric power, ships, metallurgy, energy systems and other body pipelines as a regulating and intercepting device.

1, Light weight: the body is made of high-grade ductile iron, the weight is about 20%~30% lighter than the traditional gate valve, easy to install and maintain.

2, Flat-bottom gate: traditional gate valve is often in the water wash pipe that is due to foreign objects such as stones, wood, cement, iron, debris, etc. silt in the bottom groove of the valve, easy to close the tight and form a leak, resilient seat gate valve bottom with the same flat bottom design of the water pipe machine, not easy to cause debris siltation, so that the fluid flow unimpeded.

3, Overall rubber cover: The gate adopts high quality rubber for overall internal and external rubber cover, the European first-class rubber vulcanization technology makes the gate after vulcanization can guarantee the precise geometry, and the rubber and ductile ink cast gate is firmly attached, not easy to fall off.

4, Precision cast valve body: The valve body is precision cast, and the precise geometry makes the valve sealing without any finishing inside the valve body.

In addition, an important reason for choosing ductile iron is that it is less costly than cast steel. The low cost of ductile iron makes this material more popular, with more efficient casting and less machining cost of ductile iron.LIWEI is a professional valve manufacturer, we sell all kinds of gate valves and butterfly valves, etc. Ductile iron gate valves are also one of the most popular products. If you need, contact us now, LIWEI will provide professional service for you.

The company is the world’s best Ductile Iron Gate Valve supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.