Selecting materials for steam piping requires a comprehensive assessment of operating temperature, pressure, and the properties of the medium. For conventional applications involving medium-to-low pressure and temperature (pressure ≤ 4 MPa, temperature ≤ 400°C), seamless carbon steel pipe (such as Grade 20# steel, compliant with GB/T 8163 or GB 3087 standards) is a widely used solution, offering a balance of good workability and cost-effectiveness.
When temperatures exceed 400°C or pressures rise, low-alloy steels (such as 15CrMoG or 12Cr1MoVG, compliant with the GB 5310 standard) may be selected, as they offer superior high-temperature strength and oxidation resistance compared to carbon steel. In large-scale, high-temperature, high-pressure systems, martensitic heat-resistant steels like P91 (ASTM A335) can meet even more rigorous demands. For sectors such as chemical processing, pharmaceuticals, and food production-where cleanliness or corrosion resistance is critical-stainless steel piping (e.g., 304 or 316L) is preferred, despite the higher cost. Copper piping (such as T2 pure copper) offers excellent thermal conductivity but is suitable only for limited applications, such as low-pressure/low-temperature systems or small-diameter heat tracing.
Note that plastic piping is unsuitable for transporting high-temperature, high-pressure steam; for buried or overhead insulated lines, a "pipe-in-pipe" structure-consisting of an inner steel service pipe, an insulation layer, and an outer protective casing-is commonly employed. Final material selection should be based on relevant design standards (e.g., GB/T 8163, GB 3087, GB 5310) and specific operating parameters to ensure the piping system is safe, reliable, and cost-effective.