The market application range of steel-clad steel steam-insulated pipes is expanding with the vigorous development of urban centralized heating and cogeneration. The technology of thermal pipeline has been widely used in China. The direct-burial installation method, with its excellent insulation effect, high energy-saving efficiency, minimal land occupation without affecting urban planning, easy installation, short construction period, long service life, and low maintenance costs, has been universally favored upon its introduction. The types of outer sheath for the direct-buried steam-insulated pipes primarily used in China include "plastic-clad steel" and "steel-clad steel." The technical route for steel-clad steel burial involves replacing brick or concrete culverts with steel sleeve pipes on the basis of traditional trench laying. The sliding interface of the pipeline is between the pipeline support and the inner wall of the steel sleeve. Direct-buried steam pipelines; direct burial; external fixation; internal fixation. In recent years, there have been many trials of direct-buried steam pipelines in northern cities. When steam pipelines cross major city roads and when issues of environmental beautification are involved, the direct-burial laying method can effectively address these issues, and due to its fast construction progress, good insulation performance, low construction cost, and material savings, it has been increasingly widely used. Since the direct-buried steam pipeline is a new phenomenon, the national construction department has not yet formulated formal standards for detailed provisions on direct-buried steam pipelines.

Steel-clad steel-insulated pipe manufacturers offer direct-burial steam pipelines at competitive prices. These pipelines, as a new material in the heating industry, are gaining wider application due to their fast construction progress, excellent insulation performance, low construction cost, and material savings. Since there are no design specifications for high-temperature steam pipelines, the insulation structures and fixing methods vary among manufacturers. This article discusses several common characteristics of direct-burial steam pipelines available in the market.