What Are the Benefits of Using Iron Ductile Pipes?

Posted on Dec 1, 2020

iron ductile pipe

Iron ductile, also known as the ductile cast iron, nodular cast iron, spheroidal graphite iron, or spheroidal graphite cast iron, is made of graphite with another mixture of alloys.

What Is an Iron Ductile Pipe?

An iron ductile pipe is a pipe that is made of ductile iron, which is usually applied in the pumping systems of potable water, sewage, slurries, and process chemicals since the iron ductile pipe performs well in the strength and ductility that it has.

Iron ductile, also known as the ductile cast iron, nodular cast iron, spheroidal graphite iron, or spheroidal graphite cast iron, is made of graphite with another mixture of alloys. In the microstructure of this material, it is presented as the spheroidal or nodular form, which is, compared to the gray iron, stronger and more ductile for being bent or shaped.

The special properties of the iron ductile or ductile iron make it be widely adopted as the materials of the applications that require better resistance for impact or corrosion and better durability as well.

However, the material of the iron ductile pipe itself, which is the ductile iron, is not good at corrosion resistance. Therefore, the iron ductile pipe is usually protected from the interior and the exterior.

The interior lining of the iron ductile pipes can be covered by polyurethane (PUR) or cement mortar. Polyurethane is a thermosetting plastic without containing solvents. The iron ductile pipes that are made of polyurethane should be careful in installation in order to prevent the damaging of this material.

In addition, the iron ductile pipes with the polyurethane lining are corrosion resistant in drinking water, wastewater, de-mineralized water, industrial water, gas, or sulphuric acid.

Cement mortar, which is the common material in the fields of construction or building, is another iron ductile pipelining since it also performs well in reducing the possibility for the pipes to be corroded.

Besides the interior protection of the iron ductile pipes, the exterior of these pipes is usually coated with loose polyethylene sleeving (LPS), zinc, asphalt, or water-based paint. These materials are all effective for increasing the ability of the iron ductile pipes to resist corrosion in the environments where they are.


How Is an Iron Ductile Pipe Made?

There is a variety of casting methods that are applied to produce various materials for being further machined to make the final products. Considering the configuration of the long and cylindrical shape with a hollow interior, the iron ductile pipes are made by centrifugal casting.

As the name implies, centrifugal casting utilizes the centrifugal force that is produced during the casting process, to form the shape of the iron ductile pipes naturally, which is an effective way in making the iron ductile pipe stable and durable.

Centrifugal casting can be divided into three types based on the casting dimensions and methods, including vertical centrifugal casting, horizontal centrifugal casting, and vacuum centrifugal casting.

The iron ductile pipes are often made by horizontal centrifugal casting, as the longer casting length that their applications require. The horizontal centrifugal casting is conducted with a lateral working dimension.

To conduct the horizontal centrifugal casting, a die that is configured as the shape of the pipe should be heated in advance. When the temperature of the die reaches the required degree, the molten mixture of alloys would be poured into the die through a funnel.

The funnel is set beside the die and delivers the molten metals from the lateral dimension. At that time, the die that is configured as the shape of a pipe would rotate rapidly. The high-speed rotation of the die is for offsetting the gravitational forces, in order to make the following processes go smoothly.

When the pipe-like die rotates at a high speed, the centrifugal force would be produced, and the centrifugal force would distribute the molten metals evenly to form the shape of the iron ductile pipe.

After the iron ductile is formed as shaped as the pipe, it would be left for cooling off. Once the iron ductile cools and solidifies, the outer die would be removed, and the iron ductile would be turned to secondary refining produces, then the iron ductile pipe is made.

The outside diameter of the iron ductile pipe is obtained by the inside diameter of the die, and the inside diameter of the iron ductile is determined by the number of metals that are poured into the mold.


Why Choose Iron Ductile Pipes over Gray Iron Pipes?

In addition to the iron ductile pipes, there is another choice for making pipes for the related application, which is the gray iron. However, the iron ductile is gradually substituted for gray iron nowadays, since this material owns a variety of advantages that make it be preferred to use more, including:


● greater strength

When it comes to casting iron, the comparison of the different types of it would fall to the strength that each type owns. The strength includes the yield strength and the tensile strength.

The yield strength, which is the maximum stress that can be withstood before permanent deformation, and the tensile strength, which is the strongest force that can be given before the material breaks, of the iron ductile pipes, are both greater than the gray iron pipes.


● greater ductility

The ductility of a material is related to the microstructure and the proportion of the elements that the material has.

Since the iron ductile, which is the material of the iron ductile pipes, is presented as spherical or nodular form, and the more proportion of magnesium that the iron ductile has, both make it more ductile than the gray iron.


● greater impact resistance

The iron ductile pipes are capable of resisting a minimum of 7 foot-pounds of impact, while the pipes that are made of gray iron are able to resist 2 pounds of impact only, which makes the impact resistance of iron ductile pipes greater than the gray iron pipes.


● more durable

According to the research, the application of iron ductile pipe has lasted for over 100 years, which proves that the iron ductile pipes are extremely durable. Considering the above parameters which show the greater strength and ductility of the iron ductile pipes over the gray iron pipes, the durability of the former is definitely better than the latter for sure.


● lower entire cost

The cost of producing and applying the iron ductile pipes and the gray iron pipes can be compared from the short-term and long-term perspective respectively.

From the short-term perspective, since the manufacturing of iron ductile is more intricate and takes more procedures to complete than the manufacturing of gray iron, the primary cost for the installation of iron ductile pipes would be more than that of the gray iron.

However, from the long-term perspective, the entire cost of iron ductile pipes would be less than the gray iron pipes, because of the advantages that the iron ductile pipes have, including greater yield and tensile strength, greater ductility, greater impact resistance, and longer durability, which are mentioned above.

With the advantages that the iron ductile pipes have, the requirement of repairing or replacing them is reduced a lot, which is the reason why iron ductile pipes are more economical in the entire cost.


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