... rainwater, sewage discharges; 2, industrial wastewater discharge, residential drainage works; 3, salt brine, fishing, water; 4, mine ventilation, ... of tube (hole of the double-wall corrugated pipe); 7, the water works; 8, low-voltage cable and communication cable ... sizes and shape are also available upon requestRemarks: The pipe products are agree with National or Industrial Standards and Certifications ...