Polyurethane Insulated Pipe, full name: High-Density Polyethylene Plastic Outer Sheath Pre-Fabricated Direct Burial Insulated Pipe with Polyurethane Foam Insulation, which is assembled by combining the working steel pipe for conveying medium, polyurethane insulation layer, and polyethylene plastic outer sheath sequentially through equipment.
National standard polyurethane insulated steel pipes are structured in three layers from inside to outside.
Layer 1: Working Steel Pipe Layer - Generally, seamless pipes (GB8163-87), spiral-welded pipes (GB9711-88; SY/T5038-92), and straight seam welded pipes (GB3092-93) are selected according to design and customer requirements. After being treated with an advanced shot blasting rust removal process, the steel pipes can achieve a rust removal grade of Sa2 as per GB8923-1988 standard, with a surface roughness of R=12.5 micrometers as per GB6060.5-88 standard.
Second Layer: Insulating polyurethane layer, formed by injecting the liquid raw material of rigid polyurethane foam plastic into the cavity between the steel pipe and the outer sheath with a high-pressure foaming machine in one go. This is commonly referred to as the "pipe-in-pipe foaming process." Its functions include: 1) waterproofing, 2) thermal insulation, and 3) supporting the weight of the heating network. When the temperature of the medium being transported ranges from -50℃ to 120℃, rigid polyamine urethane foam plastic is used as the insulation layer.
Three Layers: High-density polyethylene protective layer, preformed black (yellow) plastic pipes with specified wall thickness, serving the purposes of protecting the polyurethane thermal insulation layer from mechanical damage and preventing corrosion and water damage.
Product Structure: Pre-fabricated buried steam-insulated pipe consists of the core pipe (working steel pipe), reducing layer, insulation layer, reflective layer, securing steel belt, sliding bracket, air layer, outer steel pipe, spray polyurethane, and wrapped glass fiber reinforced plastic.
Features:
Made of steel pipes for external protection, with high strength and resistance to damage, capable of bearing substantial overhead loads. To achieve a long lifespan, anti-corrosion treatment is required for the steel jacket pipe.
The rolling support structure design is rational, featuring minimal rolling friction and reduced load on the fixed supports. The mechanical analysis principle is straightforward, significantly enhancing the stability and safety of the pipeline.
The vacuum layer completely eliminates heat conduction and convection through air layers, reducing heat loss. Compared to an air layer structure, it can lower the outer wall temperature by 8-13°C with the same insulation thickness.
The vacuum pump device completely solves the problem of internal wall corrosion of the outer steel casing caused by hot and humid air, significantly extending the service life of buried steam pipelines. The product lifespan is increased to 30 years.
