Polyurethane Insulated Pipe, full name: High-Density Polyethylene Plastic Outer Sheath Pre-fabricated Direct Burial Insulated Pipe with Polyurethane Foam, which is sequentially combined from the working steel pipe for conveying medium, polyurethane insulation layer, and polyethylene plastic outer sheath through equipment.
National standard polyurethane insulated steel pipes are structured in three layers from the inside out.
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 advanced shot blasting rust removal technology, the steel pipes can achieve rust removal grade Sa2 as per GB8923-1988 standard, with a surface roughness of 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 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 conveying medium is between -50℃ and 120℃, use rigid polyetherimide foam plastic as the insulation layer.
Layer 3: High-density polyethylene protective layer. Preformed black (yellow) plastic piping with a certain wall thickness, serving dual purposes: to shield the polyurethane insulation layer from mechanical damage and to prevent corrosion and water damage.
Product Structure: Pre-fabricated buried steam-insulated pipes consist of a core pipe (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 withstanding significant overhead loads. To ensure longevity, anti-corrosion treatment is necessary for the steel jacket pipes.
The rolling support structure is designed rationally with minimal rolling friction, reducing the load on the fixed supports. Its mechanical analysis principle is straightforward, significantly improving the pipeline stability and safety.
The vacuum layer completely eliminates thermal 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 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 buried steam pipelines. The product lifespan is increased to 30 years.
