Why the stainless steel
The growing popularity of stainless steel flues is due to the specific characteristics of these products, which are decidedly better than the traditional systems used in the building and plant sectors for the discharge of fumes. AISI 316L (1.4404) austenitic stainless steel flues have high resistance to the corrosive effects of acid condensate and low resistance to the fumes’ flowing. Besides that, they reach and exceed the “dew point” (temperature value giving rise to the forming of condensation) very quickly. Their straight shape makes it easy to insulate them in order for the inside wall to maintain a suitable temperature.
Roccheggiani’s production of stainless steel flues stands out thanks to the high quality of the materials used and the innovative manufacturing processes adopted. In particular the use of AISI 316L steel stainless prevents the deterioration of the inner wall due to the effects of heat and to the chemical and mechanical stresses, thus causing working anomalies and probable damage to people or property.
Effects of fumes residual heat: the temperature value greatly depends on the kind of heat generator used. The interval varies from about 50°C for condensation wall-mounted boilers to over 300°C for fireplaces and wood-burning stoves. Roccheggiani’s products are designed in consideration of the effects of heat expansion. Special manufacturing characteristics, as well as specific indications on installation, aim at avoiding that the chimney may be damaged by the impossibility of properly absorbing heat expansion.
Effects due to corrosion: the sometimes combined presence of nitric acid and sulphuric acid, whose aggressive action is enhanced by combustion air being contaminated by chlorine or other corrosive substances, may severely damage the wall touching the fumes. In fact, in some environments, such as industrial laundries, dry-cleaner's shops, hairdresser's shops, the acids used (having a high concentration of chlorine) if dissolved in the air are highly corrosive.
The use of AISI 316L (1.4404) austenitic stainless steel in Roccheggiani’s modular elements guarantees resistance to the most corrosive components and make the flue suitable to be used with several kinds of fuel and under different weather conditions.
Gas and condensate impermeability: the sealing of combustion products is a requirement that concerns the more general concept of safety, as the fumes are highly toxic owing to the presence of sulphur monoxide and carbon monoxide, according to the different situations. Recent trends in plants have made the sealing issue even more important. The objective of reaching high performance leads to lower and lower fumes’ temperatures associated with more condensate. Besides that, the growing popularity of forced-draught fume discharge systems has increased the diffusion of chimneys working under positive pressure conditions. Roccheggiani’s range is characterised by a fast coupling system with “tongue and groove joint”; the application of a silicone gasket guarantees a perfect seal between the elements that work under positive pressure or high condensate conditions. The external joint bands guarantee that connections remain stable even under mechanical stress.