Copper, Brass or Bronze?
Copper has been used by man since 8700BC. The fact that is it still so extensively used proves its worth. Consequently copper and copper alloys are the material of choice for long lasting and reliable water distribution systems. The ease of installation and reliability they afford makes them a cost effective option, and their wide range of mechanical properties makes them some of the most versatile engineering materials for use in multiple applications.
In the HVAC sector, there are three main types of copper used; Copper, Brass and Bronze. Each variation has its own advantages and disadvantages dictated by their own material properties.
Copper itself has excellent resistance to corrosion under normal conditions. It is resilient in high temperatures and resistant to UV degradation. It is lightweight, easy to handle and 100% recyclable. Its high melting point is an added safety feature, as in the case of fire it will not creep like some materials such as aluminium and plastics.
Copper alloys build on these properties, enhancing them through the addition of other elements. Adding Zinc give you Brass, which brings added strength, hardness. Adding Tin give you Bronze (Gunmetal) which is extremely resilient to erosion, but at a cost of workability. Adding lead brings more malleability.
Throughout this article we will be looking at these three materials and understanding where they fit.
Copper is the material of choice for long-lasting and reliable systems. It naturally forms a protective surface film when in contact with water through copper oxide corrosion. This allows it to perform reliably over long periods of time.
When there are pollutants present however, particularly ammonia and sulphides, it will suffer. High velocities and turbulence in the system are also causes of corrosion as they prevent the copper oxide layer forming, removing its natural layer of defence. In copper systems, bends and corners are hot spots for Erosion Corrosion putting copper fittings at risk.
Brass is a copper alloy made with the addition of Zinc, which gives it added strength and hardness. This makes it more resistant to Erosion Corrosion and the higher tensile strength means it can withstand higher pressures. It is for this reason that our range of compression fittings is our highest performing range of fittings.
Through the addition of a small amount of lead to the alloy, it can be also made more malleable. This allows it to be easily forged and stamped, which means it is easy for high volume manufacturing. This allows us to be very reactive when supplying to market.
Much like copper and any other material however, in adverse conditions brass is susceptible to corrosion. When pollutants are present, brass components can suffer from Stress Cracking Corrosion. Furthermore, the addition of Zinc introduces a new form of corrosion called dezincification, which over time will compromise the strength of brass components.
Overall, brass is our highest performing material and a cost effective solution with a rich list of applications
Bronze is a copper alloy made with the addition of Tin, which makes it extremely resilient to corrosion. It is immune to dezincification and much more resilient to Stress Cracking Corrosion, crevice corrosion and pitting. For these reasons, Bronze components are chosen for the harshest environments, particularly where salt water is present.
Its material properties however do not make it particularly easy to manufacture. Bronze can only be cast, which is a much slower manufacturing process. This manufacturing process and the higher copper content makes it a more expensive option.
So Which One?
Copper is generally the cheapest, but of the three it is the most susceptible to corrosion. It is also the most susceptible to bad workmanship. You can find Copper in our range of Copper Press, End Feed and Solder Ring.
Bronze is usually significantly more expensive, but is the most resilient and in harsh environments is often the only solution when it can be used. You can find Bronze in our range of End Feed
If you require any further assistance when understand which materials and components to choose for your project, don’t hesitate to contact our technical team.