Influence of flow rate (Topic 11037)

High flow rates can give increased corrosion on aluminium because of a combined erosive and corrosive effect. The data on upper flow rate limits on aluminium are rather limited, but is often suggested to be about 2ñ3 m/s. There is evidence that this is alloy independent.

However, in addition to an upper flow rate limit, the effect of non-flowing and slow-flowing water is very important. In non-flowing and slow-flowing waters, the tendency for local attacks like pitting corrosion will be more apparent and the pitting will decrease with increasing flow rates. This happens because the build up of deposits and corrosion products will be hampered at high flow rates and the development of an acidic electrolyte within the pits will be prevented.

References [46]