Metal Pipe: Steel vs Copper Pipe

Metal pipes are a vital part of the modern world, they are used for carrying water, gas, and even electrical cables in situations where greater protection is needed. They are literally a conduit for the most vital services we use daily.

Not all pipes are made from the same material though, with many different types available, it can be hard to know which one to pick. In this article we will discuss steel vs copper pipes, as well as stainless steel pipes.

Advantages of Copper Pipes

Ease of Working

Copper is a relatively soft, malleable material. It is easily worked with basic hand tools and is especially easy to create secure joints with brazing techniques. Because of its malleability, Copper can be bent into tight shapes and radii for complex installations.

This is in contrast to steel and stainless steel, that generally require more force and complex tooling to bend, thread and join. Whilst welding is a strong and simple method, it comes with more complex requirements and is harder to do in the field.

Thermal Conductivity

Copper is extremely good at conducting heat. In some applications this is a downside, but it allows copper piping to be used for things like heat exchanges, and radiators more effectively.

Advantages of Steel and Stainless Steel Pipes

Strength

Steel is a much stronger material than copper, this yields many advantages, one of which is that steel pipes can support their own weight for greater lengths. A run of copper pipe may well need twice the amount of support brackets as steel.

The material having a higher strength also allows steel and stainless steel pipes to contain much higher pressures. In some applications in excess of 300 bar.

Corrosion resistance

Stainless steel pipes are significantly more corrosion resistant than mild steel, but are even more durable than copper too, as copper does degrade over time. This is mostly due to chemicals in the liquid it contains.

Many stainless steels are also resistant to attack from acidic and alkali solutions, allowing them to be used in a wide variety of applications in food, beverage and pharmaceutical applications.

Cost

Steel is considerably cheaper than both copper and stainless steel, and can offer most of the benefits of stainless steel, bar the corrosion resistance. Steel is a strong and cheap piping material that can be easily joined and welded.

In some cases galvanized steel can be used in place of stainless steel as a cost effective solution, but the zinc coating can restrict its application.

Why is copper pipe so expensive?

There are few reasons why copper costs more than the alternatives, such as steel, stainless steel and PVC.

• Low supply – compared to some metals such as Iron, Copper is relatively sparse on our planet, with only 22 million tons of copper mined in 2022, in contrast to the 2.6 billion tons of iron ore mined in the same year.
• Difficulty of refining – Whilst copper is not as complex as some materials to refine, such as aluminium, it requires some expensive measures in place to reduce the impact to the environment. We touch upon this more further on.
• Demand – Copper is not only revered for its piping uses, it is also used extensively for its electrical conductivity. Almost every electrical device uses some amount of copper. With the world ever increasing its production of electrical products, so too is the demand for copper.

Why does Copper turn green?

Whilst Copper does not rust in the same way that Mild Steel does, it does still oxidize with oxygen in the air. The Copper Oxide created has a distinctive green color. Thankfully, unlike steel, the initial oxidation protects the underlying metal from further corrosion.

One of the most well known examples of this phenomenon is the Statue of Liberty, which has developed a vivid green hue since its installation over 100 years ago. For more information on why copper turns green, read our blog all about it.

Is copper corrosion a problem when used for pipes?

Copper is thought to be immune from corrosion, but this is not always the case. Copper can experience high rates of corrosion from relatively low levels of salt and oxidizing acids, the main causes of corrosion in copper piping.

The chart below shows the rates of corrosion from Steel, Stainless Steel and Copper samples that have been exposed to a medium composed of water with minute amounts of salt and glucose.

It can be seen that copper is actually more susceptible to corrosion in this scenario than Mild Steel, with the corrosion rate per year being over 3 times higher.

Data Source

What are the environmental impacts of using Copper?

Copper mining can be extremely damaging to certain ecosystems. Like many elements, even metals, a small amount of copper is present in living organisms and is vital to certain functions, including the replenishment of blood vessels and connective tissue.

However, the sourcing of this element for industrial refining creates problems in the areas around the copper mines and processing plants. This is due to the leaching of copper-contaminated water into the ground.

The drastic increase in the copper concentration in the soil and water systems then affects millions of organisms and habitats, in many cases permanently. Thankfully much of the copper scrap produce can be recycled, reducing the need for copper mining.

When to use Copper and Steel pipes

The properties of steel and copper pipe tend to dictate their use cases, with specific applications making one or the other unsuitable.

Some situations include:

• Use steel, stainless steel or galvanized steel if the pipes need to span gaps unsupported, e.g. across ceiling joists.
• Use Copper if in a low flow – but confined application – fittings can be soldered to copper to route around complex shapes.
• Use stainless steel if the fluid contained is at all corrosive, acidic or caustic – check the best type of stainless steel here.
• Use steel or stainless steel over copper if the pipes will regularly experience freezing temperatures, coppers lower strength makes them more susceptible to bursting

Typical uses of Copper Pipe

• Heating systems in homes – centralized heating in houses often utilizes copper piping, as it can be made into complex runs to weave around walls, appliances and other objects.
• Cold water supply – whilst being replaced by plastic (PVC) for the most part, copper piping was commonly used for the cold water supply to homes and businesses, especially inside the property.
• Refrigerant lines in industrial or domestic HVAC – AC systems will sometimes use Copper piping for refrigerant routing.

Typical uses of Steel Pipe

• Structural – Alongside fluid carrying, steel pipes are often incorporated in to structural designs in many industries. They can be fabricated to make complex but strong and relatively lightweight components.
• Compressed Air – Steel pipes are often used to route compressed air systems, as they can contain high pressures without risk of failure, as well as being easy to join and self supporting.
• Oil and Gas – the oil industry is a huge consumer of steel piping, where it is used to carry both crude and refined product to and from refineries, and then around the world.

Typical uses of Stainless Steel Pipe

• Process equipment – equipment used in many industries from the pharmaceutical, the food and beverage require hygienic pipework, meaning the systems can be kept clean of debris, corrosion and dirt. Stainless steel is ideal for this due to its high corrosion resistance.
• Cryogenic – another unique property of stainless steel is that it performs well in extremely low temperatures, this is often utilized in HVAC systems, heat exchanger applications and scientific equipment.
• Aerospace – thanks to its resistance to corrosion and low temperatures, as well as its high strength, stainless steel and its derivatives are often used in specific low mass aerospace applications.

Conclusion

To the aid of engineers, piping is available in many different materials, and is one of the most widely used sections in industry. From this guide we hope you can now feel content in your selection between copper, mild steel and stainless steel piping, for your project.

To learn more about any of the materials discussed, feel free to visit our blog for many more helpful resources. If you’re ready to have material cut and delivered to your door at a great price, head over to our material selection tool.