Our pipe has been past through ISO9001 Quality Insurance System Certificate , Carrying our 253141798179EN545, GBT13295174591745717456 standard strictly to assure the product quality all through the manufacture process.Ductile cast iron is a kind of alloy of iron , carbon and silicon , in which graphite exists in the type of spherical, generally the size of graphite is 7-7 class, and spheriodization grade of the pipe should be controlled 1-3 class (spheroidization rate is not below80%). Thus after spheroidization, ductile cast iron possesses the nature of iron as well as the characteristics of steel. After annealing, its microstructure contains ferrite and a little pearlite possessing excellent mechanical properties.