Steel-clad steel steam insulation pipes have a wide range of market applications, expanding with the vigorous development of urban centralized heating and cogeneration of heat and electricity. The technology for thermal pipelines has been widely adopted in China. The direct-burial laying method, with its excellent insulation effect, high energy-saving efficiency, minimal land occupation, no impact on urban planning, ease of installation, short construction period, long service life, and low maintenance costs, has gained widespread favor upon its introduction. The types of outer protective casings for direct-buried steam insulation pipes mainly used in China currently are "plastic-clad steel" and "steel-clad steel." The technical route for steel-clad steel burial is based on the traditional trench laying, replacing brick or concrete trenches with steel casings. The sliding interface of the pipeline is between the pipeline support and the inner wall of the steel casing. 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 main urban roads and involve environmental beautification issues, the direct-burial laying method can effectively solve these problems. Moreover, its fast construction progress, good insulation performance, low construction cost, and material conservation characteristics have led to its increasingly widespread application. As a new thing, the construction department has not yet formulated formal standards for detailed regulations on direct-buried steam pipelines.

Several characteristics of steel clad steel insulated pipes from manufacturers, such as direct-bury steam pipelines, have led to their increasing application in the heating industry as a new material. This is due to their advantages like fast construction progress, good insulation performance, low construction cost, and material savings. Since there is no design specification for high-temperature steam pipelines, the insulation structures and fixation methods vary among manufacturers. This article discusses several common characteristics of direct-bury steam pipelines available in the market.