... delievery time. 4.better service COD pipe and machine 1)corrugated/spiral shape 2)co-extrusion forming ... becomes. It bears the high pressure, but is curving, has the discriminati on, the easy construction is ... (inner)≥34.6MPa34.6grade6.impact hammer testtemp 0°C,height 1m, 1kg hammper impact 10 times, ... no brokenpassgrade7.low tem. Fall downlow temp.-30°C, height 1m, fall down free, no brokenpassgrade8. ...