Polyurethane insulated piping, full name: High-Density Polyethylene Plastic Outer Sheath Pre-Fabricated Direct-Burial Insulated 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 outwardly through equipment.

National standard polyurethane insulated steel pipes are structured in three layers from inside to outside.

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 by advanced shot blasting rust removal technology, the surface of the steel pipes can achieve Sa2 grade as per GB8923-1988 standard, with a surface roughness reaching R=12.5 micrometers as per GB6060.5-88 standard.

Second Layer: Polyurethane Insulation Layer - Formed by injecting a liquid polyurethane foam plastic into the cavity between the steel pipe and the outer sheath with a high-pressure foaming machine in one go, commonly known as "pipe-in-pipe foaming technology". Its functions include waterproofing, heat preservation, and supporting the weight of the heat network. When the temperature of the transmission medium ranges from -50℃ to 120℃, use rigid polyether urethane foam plastic as the insulation layer.

Layer 3: High-density polyethylene protective layer - Pre-fabricated black (yellow) plastic pipes with predetermined 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-insulated pipe consists of a core tube (working steel pipe), a reducing layer, an insulating layer, a reflective layer, a fastening steel belt, a sliding support, an air layer, an outer protective steel pipe, spray-painted polyurethane, and wrapped glass fiber reinforced plastic.

Features:

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

The rolling support structure is designed reasonably with low rolling friction, reducing the load on the fixed supports. The principle of its mechanical analysis is simple, resulting in a significant improvement in pipeline stability and safety.

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