Increase in Losses Coefficient with Age for Small Diameter Pipes

A study to find the hydraulic behavior of galvanized iron and copper pipes, of ages between 15 and 50 yr and of up to 50.8 mm (2 in.) in diameter, is presented. It was found that in the galvanized iron pipes, the diameter is reduced and both the roughness and the losses coefficient increase with age. The increase in roughness is substantial and follows a parabolic law instead of the linear one usually found in the literature. For the copper pipes there is no appreciable change in these variables with age. The apparition of local narrowness, or stenosis, due to age, may cause considerable increases in the losses coefficient and eventually even close the pipe completely.