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Galvanized Pipe vs. Ductile Cast Iron: What's the Difference?

Edited by Aimie Carlson || By Janet White || Published on February 19, 2024
Galvanized pipes are steel pipes coated with zinc for corrosion resistance, while ductile cast iron is iron alloyed with carbon and silicon, known for its strength and ductility.

Key Differences

Galvanized pipes, made of steel coated with a protective layer of zinc, are commonly used in plumbing for their corrosion resistance. Ductile cast iron, on the other hand, is a type of cast iron known for its enhanced strength and flexibility, often used in heavy-duty applications like water and sewage pipes.
The zinc coating of galvanized pipes provides a barrier against rust and extends the life of the pipe. In contrast, ductile cast iron boasts superior strength and durability, with a graphite-rich composition that allows it to withstand high pressure and stress.
Galvanized pipes are lighter and easier to handle, making them suitable for domestic plumbing, while ductile cast iron pipes are heavier and more robust, preferred in industrial settings for their longevity and resistance to wear.
The manufacturing process of galvanized pipes involves coating steel with zinc, which can eventually wear off, leading to corrosion. Ductile cast iron, produced by adding magnesium to molten iron, maintains its structural integrity over time, even under harsh conditions.
In terms of cost, galvanized pipes are generally more affordable and easier to install than ductile cast iron pipes, which require specialized handling due to their weight and size.

Comparison Chart

Material Composition

Steel coated with zinc
Iron alloyed with carbon and silicon

Primary Use

Plumbing, domestic water supply
Heavy-duty applications, infrastructure

Corrosion Resistance

Good due to zinc coating
Naturally corrosion-resistant

Strength and Durability

Moderate strength
High strength and durability

Weight and Handling

Lighter and easier to handle
Heavier and requires specialized handling

Galvanized Pipe and Ductile Cast Iron Definitions

Galvanized Pipe

Galvanized pipes are a cost-effective solution for many piping needs.
To stay within budget, the contractor recommended using galvanized pipes for the project.

Ductile Cast Iron

Ductile cast iron is commonly used in industrial applications for its robustness.
The factory's heavy machinery is mounted on bases made of ductile cast iron for stability.

Galvanized Pipe

Galvanized pipes are versatile and commonly used for water supply lines.
The city's older water supply lines are primarily made of galvanized pipes

Ductile Cast Iron

Ductile cast iron is a preferred material for heavy-duty infrastructure components.
The municipal corporation replaced old pipes with ductile cast iron to improve the resilience of the water network.

Galvanized Pipe

The zinc coating on galvanized pipes offers excellent protection against corrosion.
Galvanized pipes are ideal for outdoor applications due to their corrosion resistance.

Ductile Cast Iron

Ductile cast iron is a type of cast iron known for its strength and flexibility.
The new bridge was built using ductile cast iron for its main supports due to its durability.

Galvanized Pipe

Galvanized pipes are often used in residential plumbing installations.
Most of the old houses in the neighborhood have plumbing systems made of galvanized pipes.

Ductile Cast Iron

Ductile cast iron is ideal for pipes that need to withstand high pressure.
For the underground sewage system, ductile cast iron pipes were chosen for their pressure tolerance.

Galvanized Pipe

Galvanized pipes are steel pipes coated with zinc to prevent rust.
The plumber used galvanized pipes for the house's water system to avoid corrosion.

Ductile Cast Iron

Ductile cast iron combines iron with carbon and silicon, resulting in a strong and durable alloy.
The city's water mains are made of ductile cast iron to ensure long-term service with minimal maintenance.


What is galvanized pipe?

A steel pipe coated with zinc for corrosion resistance.

Can galvanized pipes be used outdoors?

Yes, their corrosion resistance makes them suitable for outdoor use.

Are ductile cast iron pipes corrosion-resistant?

Yes, they have natural corrosion resistance.

What is ductile cast iron?

An iron alloy known for its strength and flexibility, used in heavy-duty applications.

Is galvanized piping expensive?

It's more affordable compared to other materials like ductile cast iron.

Can galvanized pipes rust?

Eventually, if the zinc layer wears off.

How does galvanization protect steel pipes?

Zinc coating prevents rust and extends the pipe's lifespan.

Why is ductile cast iron preferred for industrial use?

Due to its high strength, durability, and resistance to stress.

How long do galvanized pipes last?

Typically 20-50 years, depending on conditions.

Why are galvanized pipes popular in plumbing?

Due to their affordability and ease of installation.

What is the pressure capacity of ductile cast iron pipes?

They can handle high pressure, making them suitable for mains and sewage systems.

What makes ductile cast iron ductile?

The addition of magnesium during production enhances its ductility.

What applications are ductile cast iron pipes used for?

Mainly for water and sewage infrastructure due to their robustness.

How heavy are ductile cast iron pipes?

They are quite heavy, requiring specialized handling and installation.

What’s the lifespan of ductile cast iron pipes?

They can last over 100 years with proper maintenance.

Does the zinc in galvanized pipes pose health risks?

Not under normal conditions, but corroded pipes can leach zinc.

Are there alternatives to galvanized pipes?

Yes, like PVC, copper, and stainless steel pipes.

Is it safe to use galvanized pipes for drinking water?

Generally yes, but they can corrode over time, affecting water quality.

Can ductile cast iron be recycled?

Yes, it's highly recyclable.

Is ductile cast iron environmentally friendly?

Its durability and recyclability make it relatively environmentally friendly.
About Author
Written by
Janet White
Janet White has been an esteemed writer and blogger for Difference Wiki. Holding a Master's degree in Science and Medical Journalism from the prestigious Boston University, she has consistently demonstrated her expertise and passion for her field. When she's not immersed in her work, Janet relishes her time exercising, delving into a good book, and cherishing moments with friends and family.
Edited by
Aimie Carlson
Aimie Carlson, holding a master's degree in English literature, is a fervent English language enthusiast. She lends her writing talents to Difference Wiki, a prominent website that specializes in comparisons, offering readers insightful analyses that both captivate and inform.

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