Polyurethane Insulated Pipe, full name: High-Density Polyethylene Plastic Outer Sheath Pre-fabricated Direct Burial Insulated Pipe with Polyurethane Foam Insulation, which is assembled by sequentially combining the working steel pipe for conveying medium, the polyurethane insulation layer, and the polyethylene plastic outer sheath.
National standard polyurethane insulated steel pipes are structured in three layers from inside to outside.
One Layer: 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 processed by advanced shot blasting rust removal technology, the steel pipes can achieve a rust removal grade of Sa2 as per GB8923-1988 standard, with a surface roughness of R=12.5 micrometers as per GB6060.5-88 standard.
Second Layer: Insulating polyurethane layer. Made 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 known as the "pipe-in-pipe foaming process." Its functions include: 1. Waterproofing, 2. Insulation, and 3. Supporting the weight of the heating network. When the temperature of the medium being conveyed is between -50℃ and 120℃, rigid polyaminocarbonate foam plastic is used as the insulation layer.
Layer 3: High-density polyethylene protective layer - Preformed 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: Pre-fabricated directly buried steam-insulated pipes consist of core tube (working steel pipe), reduction layer, insulating layer, reflective layer, fastening steel strip, sliding support, air layer, outer protective steel pipe, spray-painted 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 substantial upper loads. To ensure longevity, anti-corrosion treatment is necessary for the steel jacket pipe.
The rolling support structural design is rational, featuring low rolling friction, which reduces the load on the fixed supports. The mechanical analysis principle is simple, significantly improving the pipeline's stability and safety.
The vacuum layer completely eliminates 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 solves the problem of internal wall corrosion in the outer steel casing due to hot, humid air, significantly extending the service life of directly buried steam pipelines. The product lifespan is increased to 30 years.
