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Due to its unique characteristics, pipelines have been widely used in many industries and fields. Transport liquid particles, powders, slurries, liquids, and gases. Features and advantages: high durability, high impact resistance, corrosion resistance, good self wetting, non-toxic to organisms, unique low temperature resistance, easy scaling, long service life, simple installation, etc. The pipe insulation structure is composed of internal steel pipe, external protective anti-corrosion steel pipe and polyurethane foam insulation layer. The sliding mode of pipeline insulation includes internal sliding mode and external sliding mode. Secondly, the characteristics of the two sliding modes were analyzed in detail.

1. Internal sliding pipeline insulation

The inner sliding surface is located on the outer surface of the working steel pipe. The insulation material and outer protective tube are relatively fixed. The main reason is that the thermal expansion of the working steel pipe moves within the insulation material. The structural form is mainly used for hard insulation materials. The advantage is that there is no support ring between the working steel pipe and the outer protective pipe, and the inner wall of the outer protective pipe does not need to be set. It is prone to corrosion, but the disadvantage is that it is difficult to handle leaks of heat flow. The working steel pipe for large-diameter steam pipes is independent, which can easily cause the insulation material to become eccentric or break, increasing internal friction.

2. External pipeline insulation

Due to the presence of an air layer between the insulation layer and the outer protective pipe, stagnant water in the pipeline can be discharged during transportation and construction, making it more suitable for areas with abundant rainfall and high water levels. However, for soils with high chlorine and sulfur content (especially in coastal areas), the anti-corrosion protection of external steel pipes should be strengthened. As needed, the external sliding structure can be transformed into a vacuum structure.

We want to emphasize that the design concept of the external sliding mode insulation structure comes from the heat pipe trench. The trench has been changed from a brick concrete structure to a steel casing. The sliding guide bracket is installed in the outer steel pipe to allow the working steel pipe and corresponding insulation material to slide with the outer steel shell (i.e. working steel). The working steel pipe is supported by brackets in the outer steel pipe, allowing the guide brackets to roll in the outer steel pipe, forming a "steel pipe groove" structure. This structure is mainly used as an insulation layer in soft insulation materials, effectively solving the problem of increased friction caused by radial expansion. Due to the presence of the inner support ring, it will not cause eccentricity or damage to the insulation material.