Insulated steel pipes are steel pipes that have undergone heat preservation processing, ensuring that the internal temperature of the working steel pipe meets or reaches the required temperature in different working environments and under the action of external media. These pipes are widely used in liquid and gas transmission networks, chemical pipeline insulation projects, oil and chemical industries, centralized heating and hot water networks, central air conditioning ventilation pipes, and municipal engineering projects. Steel-clad steel composite insulated pipes
Steel-clad steel composite thermal insulation pipes can be divided into two major categories based on different sliding methods:
1. Internal sliding type: The thermal insulation structure is composed of working steel pipe, aluminum silicate, drag-reduction layer, micro-porous calcium silicate, insulation layer, stainless steel fastening steel strip, aluminum foil reflective layer, polyurethane insulation layer, outer steel pipe, and external anti-corrosion layer. The internal sliding type insulated steel pipe is structured from a steel pipe for conveying medium, composite silicate or micro-porous calcium silicate, rigid polyurethane foam plastic, outer steel pipe, and glass fiber reinforced plastic shell anti-corrosion protective layer. Various pipe fitting joints have matured thermal insulation treatment technology and reliable quality.
2. External Sliding Type: Insulation structure consists of working steel pipe, glass wool thermal insulation layer, aluminum foil reflective layer, stainless steel fastening steel strip, sliding guide bracket, air insulation layer, outer protective steel pipe, and outer anti-corrosion layer.
External sliding thermal insulation steel pipe structure: 1. Inner steel pipe 2. Zinc-rich primer 3. Sliding guide bracket 4. High-temperature resistant glass wool 5. Aluminum foil reflective layer 6. Air insulation layer 7. Outer steel pipe 8. Anti-corrosion layer of outer steel pipe
Steel-clad steel composite thermal insulation pipes are a type of underground directly buried pipeline. They can be buried underground without a concrete structure, with the thermal expansion of the working steel pipe occurring inside the outer pipe, thereby reducing material costs, shortening construction time, and ensuring the safety of the heating pipeline. They can be widely used safely in different temperature environments, particularly suitable for high-temperature steam pipeline projects. The operating temperature can reach 150℃-450℃. The pipeline ends are usually sealed with polyethylene film or three-layer PE cold-spiral tape to prevent moisture or water from entering before installation or during construction. The thermal insulation material is wrapped in multi-layers with staggered seams, effectively reducing heat loss. Meanwhile, control measures are taken on the outer jacket surface to prevent the formation of cold bridges, ensuring the temperature control of the anti-corrosion layer. Multi-layers of aluminum foil reflective insulation are wrapped with thermal insulation materials, further reducing heat loss, making the steam pipeline more cost-effective. The drainage system is designed in a fully enclosed form, with flexible arrangement, reasonable structure, and reliable safety.
The moisture drainage pipe on the steel sleeve pipe can effectively expel moist gases and also serve as an alarm signal pipe for daily operations. The thermal compensation of the pipeline uses a bellows compensator, which is installed inside the sleeve and made in a direct-bury form, eliminating the need for observation wells, making construction operations convenient and shortening the construction period. Suitable for transporting steam or other media at pressures below 2.5MPa and temperatures below 350°C, this product features a steel pipe outer protective layer that is highly durable, easy to install and maintain, and has a long service life. Polyurethane insulated steel pipes are used on medium and small diameter pipelines for hot oil transportation or heating systems to reduce heat loss to the soil. The commonly used insulation material is rigid polyurethane foam plastic, with an applicable temperature range of -185 to 120°C. This material is soft and light, so to enhance its strength, a layer of high-density polyethylene is applied externally to the insulation layer, forming a composite material structure to prevent groundwater from渗入the insulation layer. The outer surface of the steel pipe is treated with shot blasting to remove rust and the outer surface of the protective tube is subjected to corona treatment using high-pressure polyurethane foam equipment, which improves the bonding properties of the insulation pipe. The insulation material is a rigid polyurethane foam with a density of 60 to 80 kg/m3, which fully fills the gap between the steel pipe and the sleeve, and has a certain bonding strength, creating a firm and integrated structure between the steel pipe, outer protective tube, and insulation layer. Polyurethane foam has excellent mechanical and thermal insulation properties, and typically withstands temperatures up to 120°C; through modification or combination with other insulation materials, it can withstand temperatures up to 180°C.
