Polyurethane insulated pipeline, full name: High-Density Polyethylene Plastic Outer Sheath Pre-fabricated Direct Burial Insulated Pipe with Polyurethane Insulation Layer, composed of the working steel pipe for conveying medium, polyurethane insulation layer, and polyethylene plastic outer sheath, which are sequentially combined outwardly through equipment.
National standard polyurethane insulated steel pipes have a three-layer structure from inside to outside.
Layer 1: Working钢管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 advanced shot blasting rust removal technology, the surface of the steel pipes can achieve Sa2 grade rust removal according to GB8923-1988 standard, and the surface roughness can reach R=12.5 micrometers as per GB6060.5-88 standard.
Second Layer: Insulation layer made of polyurethane, 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 operation. This is commonly known 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 conveying medium is between -50℃ and 120℃, rigid polyamine urethane foam plastic is used as the insulation layer.
Layer 3: High-density polyethylene protective layer - Pre-fabricated black (yellow) plastic pipes with a certain wall thickness, serving the purpose of both protecting the polyurethane insulation layer from mechanical damage and preventing corrosion and water damage.
Product Structure: The pre-fabricated buried steam insulation pipe consists of a core tube (working steel pipe), a reducing layer, an insulating layer, a reflective layer, a fastening steel strip, a sliding bracket, an air layer, an outer steel pipe, sprayed polyurethane, and wrapped glass fiber reinforced plastic.
Features:
The outer layer is made of steel pipes, offering high strength and resistance to damage, capable of bearing significant overhead loads. To ensure longevity, anti-corrosion treatment is necessary for the steel jacket pipe.
The rolling support structure design is rational, featuring minimal rolling friction, reduced load on the fixed supports, and a simple mechanical analysis principle. This significantly enhances the stability and safety of the pipeline.
The vacuum layer completely eliminates heat conduction and convection through the air layer, 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 system completely resolves the issue of internal wall corrosion in outer steel casing tubes due to hot and humid air, significantly extending the service life of directly buried steam pipelines. The product lifespan is increased to 30 years.
