The formation of thin-walled in cast iron pipe in lost foam casting was analyzed.The positions of defects were formed mainly in the last solidification location

which results from the inadequate pouring of liquid metal and badly exhaustion of decomposition of the pattern.The thin-walled defects can be eliminated by improving the fire-resistance of refractory materials

choosing large size silicon sand and controlling the pouring velocity.The results show that the production rate is greatly increased

and the pipe grade is improved.