There are three types of stainless steel commonly used for the manufacturing of flues, namely 430 grade, 304 grade and 316 grade. However, not all flues are made equal and when shopping for flues, one should be sure to take into account the type of steel used to manufacture it.
430 Grade Stainless Steel (430SS) This is the lowest grade and the cheapest stainless steel available. One can recognise 430SS, because it is the only stainless steel which has magnetic properties. Although it is preferable to have flues made from 430SS, than from mild or galvanised steel, 430SS flues will not last as long as 304SS or 316SS flues. The absence of Nickel in the chemical composition of 430SS leads to lower resistance to temperature changes and increased likelihood of corrosion.
304 Grade Stainless Steel (304SS) At Hydrofire we stock and distribute flues made from 304SS for a number of reasons. 304SS is excellent in terms of anti-corrosion properties. This is especially important when using a closed combustion fireplace where weak acids are created during combustion which, over time, corrode the inner walls of flue pipes. In a closed combustion fireplace, 304SS will last approximately twice as long as 430SS. 304SS is excellent value for money and is also non-magnetic.
316 Grade Stainless Steel (316SS) This is the best quality stainless steel available. It is non-magnetic, very expensive and referred to as “Marine Grade Stainless Steel” – typically used on yachts and luxury boats. We can supply 316SS flues by special order.