Polyurethane Insulation Pipes, full name: High-Density Polyethylene Plastic Outer Sheath Pre-fabricated Direct Burial Insulation Pipes with Polyurethane Foam, are composed of the working steel pipe conveying the medium, the polyurethane insulation layer, and the polyethylene plastic outer sheath, which are sequentially combined outward by equipment.

National standard polyurethane insulated steel pipes have a three-layer structure from the inside out.

One layer: 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 processed with advanced shot blasting and rust removal, the steel pipes can achieve a rust removal level up to Sa2 grade of GB8923-1988, with a surface roughness reaching R=12.5 micrometers as per GB6060.5-88.

Layer 2: Polyurethane Insulation Layer - Formed by injecting a liquid polyurethane foam into the cavity between the steel pipe and the outer sheath with a high-pressure foam machine, creating a single-layer rigid polyurethane foam. Commonly referred to as "pipe-in-pipe foaming technology". Its functions include waterproofing, thermal insulation, and supporting the weight of the thermal network. When the medium temperature ranges from -50℃ to 120℃, use rigid polyurethane urea foam for insulation.

Three Layers: High-density polyethylene protective layer, pre-made black (yellow) plastic pipes with specified 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 the core tube (working steel pipe), reduction layer, insulation layer, reflective layer, securing steel strip, sliding bracket, air layer, outer steel pipe, sprayed polyurethane, and wrapped glass fiber.

Features:

The outer layer is made of steel pipes, offering high strength and resistance to damage, capable of bearing significant overhead loads. To ensure a long service life, anti-corrosion treatment is required for the steel sheath.

The rolling support structure design is rational, featuring minimal rolling friction, reduced load on the fixed supports. Its mechanical analysis principle is straightforward, significantly enhancing the pipeline's stability and safety.

The vacuum layer completely eliminates the 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 under the same insulation thickness.

The vacuum pump system completely solves the problem of internal wall corrosion of the outer steel casing due to hot and humid air, significantly extending the service life of the buried steam pipeline. The product lifespan is increased to 30 years.