Investigating the corrosivity of evaporator condensates and the contributing factors

In recent years, some Australian factories have experienced high corrosion rates in condensates at the tail end of the evaporator set, requiring premature replacement of pipework and valves. Of greater concern is whether the evaporator tube plates are also being corroded at accelerated rates.

Recent research has determined that when factories operate steam efficient evaporators sets, condensate pH reduces significantly late in the set (pH < 5). One cause is the exacerbated degradation of monosaccharides to acids under steam-efficient operations.

This project has measured average and instantaneous corrosion rates, using coupons and a corrator, in final condensates at four factories. The results have defined the magnitude of the problem, the variability of corrosion rates in the condensates at the different factories and has helped to identify less corrosive construction materials.