• Home
  • Copper vs Stainless Steel

Does a stainless steel piping solution outperform copper? Here are the facts

Copper has been the de facto standard as a means of transporting drinking water into homes and buildings for years. As science and technology evolve, we often see things in a new light, whether it's research into health, environmental factors, or the evolution of products. Given this, it’s worth reviewing copper’s use in water transfer solutions and seeing whether we have better options available now.

In this article, we look at some facts about stainless steel piping, and ask the fundamental question:

‘Is it time to retire copper piping solutions for good?’

The case for stainless steel piping over copper


When looking at a piping solution for water and gas transfer, we need pipes that tick all the boxes. We need them to be strong, durable, and easy to work with. Engineers need to be satisfied with the performance properties, but also are cognisant that our customers also need a solution that is cost-effective and seamless.

Copper is a soft and highly malleable material. This feature can be beneficial in some applications; however, in large water and gas installations, it can pose numerous issues. Stainless steel is more rigid and 40% stronger compared to copper. Stainless steel doesn’t need as much support as copper because it has greater tensile strength and is 9% less susceptible to thermal expansion on average. It is calculated to be able to reduce bracketing requirements by up to 40%.

    Then there’s the issue of welding joints and hot work permits. While some copper pipe joints can be crimped using a press-fit tool, copper sizing is limited to 100mm in press-fit fittings. Conversely, stainless steel press-fit pipes can go up to 168mm, allowing a higher flow rate.

    How do the two compare in terms of sustainability and cost?


    When comparing the cost of raw materials for piping systems, both copper and stainless steel have their unique advantages and disadvantages. Copper tends to be susceptible to higher cost fluctuations in its raw state, especially in larger sizes. Although press-fit copper can cost approximately 10% less than stainless steel at 15mm, research shows that the cost advantage diminishes as the pipe size increases. For instance, at 28mm, copper costs around 19% more, at 54mm, it costs 22% more, and at 108mm, it costs 24% more. Braised copper typically has a lower cost, but this is offset by its higher installation cost.

    Theft is a hidden cost as both households and commercial properties can be targeted, where stolen copper is sold for scrap at recycling yards. As long as copper prices continue to rise worldwide, so too will the instances of copper pipe theft.

    Sustainability is another important factor to consider when selecting materials for piping systems. Stainless steel stands out as a more sustainable option, with a low carbon footprint due to its production process without the use of harmful chemicals. It is also manufactured using a high proportion of recycled material and is 100% recyclable. In contrast, copper is shown to cause problems when recycling, notably as an end-of-life recycling constraint.

    Another constraint on copper is that it cannot be used in certain applications, such as pipework carrying diesel fuel, where copper can cause diesel to polymerize and thicken. Moreover, the pressure rating of copper pipes reduces dramatically as the size increases in high-pressure systems, and high-velocity systems cannot use copper pipes due to the risk of corrosion, which increases as the flow rate increases.

    Therefore, when deciding which material to use for a piping system, it is crucial to consider both the cost and sustainability factors. While copper may be more affordable in smaller pipe sizes, it may not be the most financially and environmentally sustainable option for all applications.

    Are there positive health impacts using stainless steel instead of copper piping?


    Research over the last 10 years has uncovered that copper ions are released into drinking water where copper pipe is used. Studies by the European Commission into which type of pipe had the least emissions leaching into drinking water found that stainless steel fared much better than copper.

    While humans can absorb some amounts of copper without adverse health impacts, the older the copper pipes are, the higher the concentration of copper ions released into drinking water through corrosion. People who come into contact with copper through working with the material or consuming copper ions leached into their drinking water can lead to copper fever, a flu-like condition, and in large quantities, copper poisoning.

    Stainless steel does not in any way promote the growth of “biofilm”, which is an essential element for the development of bacteria, whereas copper does.

    Another benefit of stainless steel is in the material itself. It has a smooth hard oxide layer making it hard for bacteria and microorganisms to hide in. Copper’s topography has a surface that promotes bacteria growth as it is easier for the bacteria to find shelter in the material.

    Just as copper replaced the use of lead before, it is likely that stainless steel will eventually replace copper as the material of choice when it comes to function, form and from a health standpoint. Could stainless steel completely override the use of copper in the near future? For health reasons alone, this would not be a far stretch to conclude.

    In many parts of the world including Switzerland, Germany, Italy and Denmark, the appetite for copper piping is decreasing and being replaced by stainless steel as the material of choice.

    Is flow rate and heat transfer something we need to examine, and if so, why?


    Flow rate is crucial in piping solutions because it determines how much fluid or gas can be transported through the pipeline, affects pressure and velocity, and impacts the overall performance and reliability of the system. Proper consideration of pipe diameter, valve size, and pump capacity is necessary to ensure the required flow rate is achieved while maintaining necessary pressure and flow conditions.

    Stainless steel is corrosion-resistant and is protected by the formation of a self-repairing passive oxide film. Copper, on the other hand, is prone to oxidation, leading to corrosion over time. Additionally, the surface of copper is 17% rougher than that of stainless steel, making it more susceptible to structural corrosion at higher water flow rates. Water flow above 2m/second causes structural corrosion in copper. Stainless steel is corrosion resistant given it takes 6m/second to affect the inner wall of stainless steel, leading to greater efficiency with increased structural integrity.

    The graph below shows how water velocity impacts the corrosiveness of the pipe over time.

    We can see how radically different the results are when comparing copper versus stainless steel piping.



    Engineers understand all too well that heat transfer is critical in piping solutions as it affects the performance, efficiency, and safety of the system. Proper management of heat transfer is essential to maintain the desired fluid temperature, prevent overheating, and minimise energy losses. Heat transfer can occur through conduction, convection, or radiation, and can impact the material selection, insulation, and design of the piping system. Therefore, understanding and controlling heat transfer is crucial for engineers designing or maintaining piping solutions.

    Stainless steel has a lower heat conductivity ratio than copper, meaning it is less susceptible to heat loss. Copper, on the other hand, requires more insulation to prevent heat loss. Stainless steel thermal conductivity is 1/25th that of copper, making it a better choice for applications where heat transfer needs to be minimised.



    Another benefit of stainless steel press-fit piping systems is their strength and durability. Copper piping is weaker and more susceptible to damage from external knocks during storage and installation. Stainless steel, on the other hand, is a strong and durable material that can withstand high-pressure ratings of up to 4000kpa and high flow rates exceeding 4m/s. Copper's pressure rating reduces dramatically as the size of the pipe increase.

    Case study: Installation of Surepress Stainless Steel press-fit solution for the NSW Maitland Hospital build


    The NSW Government commissioned a new hospital build to service the communities of the Hunter Valley NSW and its surrounds, with a project budget close to $500 million.

    The Project team and engineers needed a world-class solution that could deliver hot and cold water, and gas throughout the hospital’s underlying infrastructure. The brief was to deliver the solution cheaper without compromising on quality and providing a safe work environment at the same time.

    Allmach’s Surepress press-fit stainless steel pipe, fittings and custom-fabricated manifolds were chosen to deliver an impressive total of 15 kms of stainless steel pipe.

    Being a press-fit installation, safety and expediting of the install were done without the need for hot work permits. Quality assurance procedures were met using the Surepress press-check sleeve film visual confirmation and using leak path O-rings. Having a visual quality confirmation made the installation easier and faster, with the comfort of peace of mind the joints were leakproof. The guarantee is an inherent feature of the press-fit solution.

    The Surepress system is corrosion-proof, leak-proof and has wash-down properties. The Surepress 316L stainless steel press-fit system made the gas and water pipe installation faster, easier, and safer to install than traditional copper pipe, saving significant time and money.

    The installers were able to crimp Surepress fittings up to 168mm, an advantage over copper pipe that can only be crimped up to 100mm – anything larger would need welding.

    With long lengths of service piping throughout supporting the hospital’s infrastructure, the installers avoided extensive bracketing to support the pipes, as would have been needed with copper piping. The strength and rigidity of our stainless steel pipes were another project saving in installation time and cost, recognised by the construction and instal teams.

    By using stainless steel press-fit, the installation saw results 10x faster than conventional welding. This reduced installation time, while cutting overall costs by just under 30%.



    Conclusion


    In summary, we have seen the facts and tangible benefits of a press-fit stainless steel piping solution.

    We’ve noted that stainless steel outperforms copper in every aspect; from flow rates and velocity, to ease of installation and both time and cost savings, all done to the highest quality control standards.

    We’ve also seen examples of how some European countries are increasingly choosing stainless steel over copper, for the positive health benefits associated with stainless steel piping. Allmach’s Surepress stainless steel press-fit piping solution is superior to copper piping in every way.

    Allmach is an Australian piping systems supplier with a focus on sustainable infrastructure delivery and innovative solutions including leak detection. Allmach is ISO9001 certified and is a major wholesaler and distributor of PVC, Polyethylene, Carbon Steel & Stainless Steel, Aluminium, and pipe, fittings and valves, suitable for the delivery of mains water, wastewater and water treatment, in particular chemical dosing and aeration.

    Allmach’s Surepress press-fit piping solution is backed by a 25-year manufacturer’s guarantee, uses AS5200-compliant stainless steel and is AGA, ActivFire and WaterMark certified.

    www.allmach.com.au