Compared with other conventional insulated pipes, steel-in-steel direct-buried pipe has many advantages. In developed countries it is already a relatively mature, advanced technology; in China it is a rapidly developing technology and market demand is growing quickly. Some of its advantages are described below. Steel-in-steel insulated pipe has excellent thermal insulation. Under ordinary conditions it can withstand temperatures up to 120°C; by modifying its properties or combining it with other insulation materials, its heat resistance can reach 180°C, so it can be used in a wide range of hot- and cold-medium insulated-pipe projects.
Steel-in-steel insulated pipe has excellent mechanical properties and better load-bearing capacity than conventional insulated pipe. In addition to excellent thermal insulation, it uses a direct-buried district-heating pipeline arrangement that can greatly reduce project cost. Steel-in-steel insulated pipe is laid by the direct-buried method and does not require construction of large trenches; the insulated pipe is simply buried underground, which greatly reduces land occupation and cost.
The main advantages of steel-in-steel insulated pipe are the four points above. It is precisely these main advantages that have made it a leading product in the insulated pipe field and further facilitated people's lives and production. Steel-in-steel direct-buried pipe laying technology is a waterproof, leak-proof, seepage-resistant, and pressure-resistant method for direct-buried insulated pipes, insulated pipelines, PU spray coating, and insulation materials.
PU insulated pipe requires reliable, tight waterproofing and, in addition, excellent mechanical strength. Because of its high strength and welded connections, a steel casing offers highly reliable waterproof sealing; moreover, its heat resistance is unmatched by other outer jackets. Direct-buried insulated pipe, insulated pipeline, PU spraying, insulation materials, PU insulated pipe. In areas with a high groundwater table, to ensure that groundwater does not affect the normal operation of direct-buried steam pipelines, a strong, sealed steel outer shell is the preferred protective jacket.
The insulation structure of steel-in-steel direct-buried pipe can be divided into two main types according to the sliding method: 1. Internally sliding type: the insulation structure consists of the carrier pipe, aluminum silicate, an anti-friction layer, microporous calcium silicate, a thermal insulation layer, stainless-steel fastening bands, an aluminum-foil reflective layer, a PU insulation layer, the outer steel pipe, and an outer anti-corrosion layer. Internally sliding insulated steel pipe is composed of the medium-carrying steel pipe + composite silicate or microporous calcium silicate + rigid PU foam + outer steel pipe + FRP-shell anti-corrosion protective layer.
Insulation treatment techniques for various pipe-fitting nodes are mature and quality is reliable. 2. Externally sliding type: The insulation structure consists of a carrier pipe, a glass-wool thermal insulation layer, an aluminum-foil reflective layer, stainless steel fastening steel bands, sliding guide supports, an air insulation layer, an outer protective steel pipe, and an external anti-corrosion layer.
