... ducts 4)make machine also, prompt delivery COD cable pipe Corrugated Optic Duct It uses friction coefficient ... of the outer duct by means of assembling cable ducts in the course of production. Both inner ... 34.6MPa34.6grade6.impact hammer testtemp 0°C,height 1m, 1kg hammper impact 10 times, above 9 ... .low tem. Fall downlow temp.-30°C, height 1m, fall down free, no brokenpassgrade8.inner side friction ...