Polyurethane Insulation Pipe, full name: High-Density Polyethylene Plastic Outer Sheath Pre-Fabricated Direct-Buried Insulation Pipe with Polyurethane Foam, consists of a working steel pipe for conveying medium, a polyurethane insulation layer, and a polyethylene plastic outer sheath, which are sequentially combined outward by equipment.

National Standard Polyurethane Insulated Steel Pipe consists of three layers from inside to outside.

One Layer: Working 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 process, the surface rust removal level of the pipes can reach Grade Sa2 as per GB8923-1988, and the surface roughness can reach R=12.5 micrometers as per GB6060.5-88.

Second Layer: Insulation made of rigid polyurethane foam, injected once into the cavity between the steel pipe and the outer sheath using a high-pressure foam machine. This process is commonly known as "pipe-in-pipe foaming". Its functions include: 1) waterproofing, 2) thermal insulation, and 3) supporting the weight of the thermal network. For medium transportation temperatures ranging from -50℃ to 120℃, use rigid polyether urethane foam as the insulation material.

Layer 3: High-density polyethylene protective layer - Pre-fabricated black (yellow) plastic pipes with specified wall thicknesses, serving dual purposes: 1) To protect the polyurethane insulation layer from mechanical damage by hard objects, and 2) To prevent 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 insulation 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 achieve a long service life, anti-corrosion treatment is required for the steel jacket pipe.

The rolling support structure design is rational, featuring low rolling friction, which reduces the load on the fixed supports. The mechanical analysis principle is straightforward, significantly enhancing the pipeline 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 extraction device completely resolves the issue of internal wall corrosion of the outer steel casing due to hot and humid air, significantly extending the service life of buried steam pipelines. The product lifespan is now up to 30 years.