Striped slag is often appeared in the spigot position of centrifugal ductile iron pipes.The average thickness of slag layer is about 5～10 mm with black and dense structure

resulting in poor appearance and worse internal performance.The analysis reveals that the Si content in the stripped slag reaches 65.15%

and the "silicon rich structure" is formed by the accumulation of iron melt inoculant in the socket site without melting and diffusion.The stripped slag is mainly attributed to the advanced flow of Fe liquid.According to the analysis

through refining molten iron and strictly controlling the advanced flow of molten iron as well as pouring at high temperature

keeping uniform flow of the liquid Fe in the flow slot and matching with inoculants

stripped salg can be eliminated effectively.