The issue of corrosion in hot water cylinders and calorifiers is a key issue for many companies as they look to invest in a hot water solution, that will not only deliver the capacity, flow rate and efficiency required, but also will last for as long as possible.
McDonald Engineers are seeing a growing number of enquiries from clients looking to replace stainless steel with high performance copper cylinders. This has been particularly evident in the commercial sector, where stainless steel calorifiers have failed after 2 to 3 years with corrosion. The contractors in these situations are reverting back to copper, which is tried and tested and is extremely resilient against corrosion.
There is a general mistaken belief that Stainless Steel cannot corrode, however this is not the case. The production methods used can make it much more susceptible to corrosion than copper.
The key to maintaining high levels of resistance within stainless steel, is maintaining the passive layer on the material which protects it from corrosion. The manufacturing process of a stainless steel cylinder actually attacks the passive layer of stainless steel and if the welding process is not carried out correctly, can greatly reduce the corrosion resistance of the metal.
Producing a stainless steel hot water cylinder, requires a time consuming manufacturing process. This includes purging the cylinder with a backing gas when welding and then pickling of the cylinder to ensure the corrosion resistance is fully restored.
If this is not carried out properly, this can cause a major issue which can result in rapid corrosion, well before the predicted life span.
Copper, on the other hand, is a non-reactive base metal and is therefore extremely resistant to corrosion – so much so that the material can be used for roofing and guttering.
The manufacturing process of copper cylinders involves seam welding and brazing which use a copper phosphorous wire to reduce the temperature of the filler, as opposed to melting the base material. This provides much more consistent and stable joints, which dramatically reduces the likelihood of corrosion.
The prudent approach to minimising corrosion issues and therefore the likelihood of a cylinder failing, is to use copper hot water cylinders and calorifiers, manufactured by a high quality company you can trust.