SR8 Durability of stainless steel flues (1988)

Over recent years, the advent of the closed combustion solid-fuel stove in New Zealand has led to an increased usage of metal flues (currently estimated to be about 250,000) and in particular lightweight stainless steel flues. However, it is becoming increasingly apparent that some of these flues are not living up to expectation. Rather than remaining stainless, some have degraded at an alarming rate, leading to perforation after 3-5 years of use.

In order to understand some of the factors influencing the early degradation of stainless steel flues, a review of the literature was carried out, and this study report discusses the findings. It also summarises the results of a survey of 17 New Zealand metal flue manufacturers to determine the materials, practices and flue designs in current use by the industry.

In addition, four case studies of stainless steel flues that had degraded in service are discussed. The report concludes that metal flues for solid-fuel stoves should be made from austenitic stainless steel, that many stainless steel flues are likely to have a limited life span and that regular maintenance and inspection of the installation is essential.