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What Are The Advantages Of Ductile Iron Over Other Metals While Casting Manhole Covers?

Dec. 07, 2021

Ductile Iron Manhole Cover


The ductile iron manhole cover is mainly made of ductile iron, or often called nodular iron. The quality depends on the nodularity. Anti-rust asphalt paint is commonly used in the casting process. In other words, the surface of ductile iron manhole covers is generally sprayed with asphalt for anti-rust treatment.


Advantages of ductile iron over other metals

Bendable yet unbreakable

Made from materials such as silicon, phosphorus, magnesium, sulfur, and more, ductile iron is used to strengthen iron covers. This makes it a highly durable material.  One more highlight of ductile iron is that it is easily bendable without breakage risk.

Compressive strength

Whilst talking about the strength, the compressive strength of that metal should be considered. In other words, it is the pressure that metal can endure or withstand so as to change its shape. The ductile has a higher compressive strength in comparison to other metals used in making manhole covers, making it the best alternative for the same.


The exposure of manholes to the vagaries of nature including hail, frost, rain, sun, and others poses a greater risk of damage. Polishing or applying a fresh coat of powder to iron can make it corrosion-resistant.  For instance, steel has higher corrosion effects, and, therefore it is recommended to use cast iron in the manufacture of manhole covers.


The most important consideration when it comes to the manufacture of manholes is cost-effectiveness.  Ductile iron, in comparison to other metals, costs less and therefore is popular in the manufacturing industry. While this ranks as an important factor that most manufacturers look into, there is no doubt that this metal has an edge over the others in terms of performance.


Features of a ductile iron manhole cover

1. High strength

The tensile strength of ductile iron is greater than 420Mpa; the yield strength is greater than 300MPa. Same as low carbon steel, it is more than 3 times that of gray iron.

2. Good toughness

The impact value is similar to that of carbon steel and 10 times that of gray iron.

3. Good plasticity

The elongation rate is greater than 7%, which is similar to high-carbon steel and gray iron materials.

4. Corrosion resistant

In the 90-day spray corrosion test performance of ductile iron, the corrosion was only 0.25 times that of pipelines and 0.1 times that of gray cast iron pipelines. The service life is 2 times longer than gray cast iron pipes and 5 times longer than ordinary steel pipes.

In most municipal applications, such as water, saltwater, steam, etc., the corrosion and oxidation resistance of cast iron exceeds that of steel. Due to the microstructure of spherical graphite cast iron, nodular graphite cast iron is better than steel in reducing vibration capabilities.


Advantages of a ductile iron manhole cover

1. Low cost

Low cost is an important reason why cast iron is more acceptable than steel, which makes ductile iron more popular. The casting efficiency is higher, and the processing cost of ductile iron is lower.

2. Lightweight

There is another advantage of ductile iron manhole covers. Ductile iron has high strength and toughness, which makes ductile iron manhole covers 30% lighter than similar manhole covers made of gray cast iron.


Find the best ductile iron manhole cover

Cangzhou Chuangxin Metal Products Co., Ltd. is China's leading SMC municipal drainage and metal product processing R&D manufacturer. Advanced automation equipment has an annual production capacity of 30,000 tons of SMC polymer municipal drainage products and 5,000 tons of metal products. The product range includes SMC composite manhole covers, ductile iron manhole covers, polymer concrete U-shaped drainage channel, drainage cover, metal access panel, metal funnel, and other construction materials. If you are interested in them, please contact us!