Mechanical Behavior of Spun-Cast Gray Iron Pipe

Past work has made little differentiation between the mechanical properties of pit and spun cast gray iron water pipes. Mechanical tests on coupons from spun and pit cast samples presented here show that spun cast gray iron has mechanical properties that fall between those of pit cast gray iron and ductile iron pipes, often with marked similarities to ductile iron. The properties determined from the mechanical tests were used to examine whether linear elastic analysis can be successfully used to approximate the mechanical behavior of a pipe loaded in bending. Linear elastic analysis was found to produce reasonable approximations to the behavior of undamaged pipes. The effect of corrosion pitting was included in the analysis by determining stress concentration factors for pits of varying depths at different stress levels. Multiplying the stress concentration factors by the results of the linear elastic analysis produced results with an error of no more than 6% from the values produced by a full cast iron plasticity analysis within the experimentally measured range of ultimate stresses.