High density polyethylene shell prefabricated directly buried insulation pipe
High density polyethylene shell from the inside out prefabricated directly buried insulating pipe are in the first layer three layer structure: steel pipe layer, work is generally selected according to the requirements of customers design and seamless tube (GB8163-87) spiral welded pipe (GB9711-88, SY/T5038-92) and straight seam welded pipe (GB3092-93). Steel tube surface after advanced shot blasting derusting processing, steel pipe descaling grade level can reach the Sa2 GB8923-1988 standard, the surface roughness can reach GB6060.5 R = 12.5 micrometers - 88 standard. The second: polyurethane thermal insulation layer, using high pressure foaming machine in the steel pipe in a cavity formed between the outer sheath one-off injection of rigid polyurethane foam plastics concentrate. That is commonly known as the "pipe in the foaming process. But its action is a waterproof, thermal insulation, 3 it is to support the heat-supply self-respect. When the temperature of the medium for: - 50 ℃, 120 ℃, use rigid poly semicarbazide acid ester foam plastic insulation layer. The third layer: high density polyethylene coating, prepared with a certain thickness of black (yellow) plastic pipe material, in the corona processing a backup. Its role is a protection against damage mechanical hard objects to polyurethane thermal insulation layer, 2 it is waterproof anti-corrosion.
High density polyethylene shell application of prefabricated directly buried insulating pipe are suitable for transporting in - 50 ℃, 150 ℃ within the scope of all kinds of medium heat/cold engineering. It is widely used in urban central heating, a warm room, cold storage, coal mines, oil port, heat/cold engineering chemical and other industries. However, high density polyethylene worse than glass fiber reinforced plastic weatherability, heat resistance is low. High density polyethylene heat resistant to 60 ℃, 70 ℃, and glass fiber reinforced plastic heat for the 100-120 degrees Celsius, therefore, we should pay attention to in the application.