чугуна K9 трубы

Ductile cast iron socket and spigot pipes and accessories shall be centrifugally casted in accordance with ISO 2531(1998) class K9 Water tightness shall be insured by the push-on joint for the pipes Composition and class Metallurgical composition of ductile iron shall confirm to the following requirements (ISO): 3.5% to 3.9% Carbon 1.8% to 2.6% Silicon Minimum tensile strength: 420(MPa) for pipes Minimum elastic limits: 300(MPa) for pipes Minimum elongation at failure: 10% for pipes Maximum hardness: 230(HB) for pipes hydrostatic pressure The pipes of class K9 shall be subject to hydrostatic pressure test in the factory as follows: DN80 to DN300:50 bars DN350 to DN600:40 bars DN700 to DN800: 32 bars Internal Lining The pipes shall be internally lined with a sulphate resisting blast furnace cement mortar. The thickness and the lines shall be in accordance with ISO 4179(1985).The lining shall be applied centrifugally. External Coating The pipes shall be externally coated in the factory with a metallic zinc coat as primer and a black bituminous or black coal tar based anticorrosive varnish in accordance to ISO 8179(1995). The zinc coat shall be applied by arc gun and the bituminous/tar based coat by an airless gun in at least 2 layers.