Mainly used in drainpipe through a flexible linkage, which has past the test of the Hebei Industrial of products Quality Intendance and inspection and the provincial appraisal and has suply the provincial gap. The product has totally gt the standards, ISO6594, DIN19522/EN877, GB12772, ASTM A88, CISI301, and KS D 4307, and has the following advantages: Flat and straight, even pipe wall, high strength and density, high smoothness on the inner and outer surface of the wall, no defects in foundry, easy installation, easy maintain, long life, helpful to environment, fireproofing and no noise.