Polyurethane-insulated steel pipes
On medium and small diameter hot oil pipelines or heating systems, an insulating composite layer is added to the external surface of the pipeline to reduce heat dissipation into the soil. The commonly used insulation material is rigid polyurethane foam plastic, suitable for temperatures ranging from -185°C to 120°C. This material is soft in texture, and to enhance its strength, a layer of high-density polyethylene is applied externally to the insulating layer, forming a composite material structure to prevent groundwater from渗入the insulation layer. The surface of the steel pipe is treated with shot blasting for rust removal and the inner surface of the protective pipe with corona treatment using high-pressure polyurethane foam equipment to improve the bonding properties of the insulating pipe. The insulation material is a rigid polyurethane foam with a density of 60 to 80 kg/m³, which fills the gap between the steel pipe and the sleeve completely, and has a certain bonding strength, forming a firm integrated whole between the steel pipe, the outer sleeve, and the insulation layer. Polyurethane foam has good mechanical and thermal insulation properties, and can withstand temperatures up to 120°C under normal circumstances. Through modification or combination with other insulation materials, it can withstand temperatures up to 180°C.
Pre-fabricated polyurethane-insulated steel pipes have a three-layer structure from the inside out:
Layer 1: Working Steel Pipe Layer
Generally, seamless steel tubes, spiral steel tubes, and straight seam steel tubes are selected based on design and customer requirements. After being treated with advanced shot blasting rust removal technology, the steel tubes can achieve rust removal grade Sa2 as per GB/T8923-1988 standard, and the surface roughness can reach R=12.5 micrometers as per GB6060.5-88 standard.
Second Layer: Polyurethane Insulation Layer
Formed by injecting the 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 referred to as "foamed pipe-in-pipe."
Three Layers: High-Density Polyethylene Protective Layer
Preformed black or yellow polyethylene plastic piping with specified wall thicknesses. Polyethylene is odorless, non-toxic, feels waxy, and exhibits excellent low-temperature resistance, with service temperatures down to -70～-100℃. It has good chemical stability, resistant to most acids and alkalis (not to oxidizing acids), and is insoluble in general solvents at room temperature. It has low water absorption but can slowly dissolve in certain organic solvents due to its linear molecular structure without swelling, and it possesses excellent electrical insulation properties. Its functions include protecting the polyurethane thermal insulation from mechanical damage and providing corrosion and waterproofing. High-density polyethylene polyurethane foam insulated steel pipes are manufactured in accordance with the standards SY/T114-2000 and SY/T115-2001.
We uphold the principles of sincere service and integrity, offering perfect service and a good attitude at equal quality, to thank our friends from all walks of life for their support and affection. Welcome to call or inquire; we will serve you wholeheartedly!
