Abstract: In petrochemical industry, ultra-high pressure steam is mainly used for turbine drive of cracking gas compressor in ethylene plant. Its transmission pipeline has the characteristics of high temperature, high pressure and large diameter. While meeting the primary and secondary stress intensity check condition requirements stipulated in ASME B31.3, this paper uses CAESAR II software to analyze the stress of ultra-high pressure steam pipeline with different pipe diameters in terms of axial displacement, compensated bending arm length, compensated bending extension, compensated bending vertical load and fixed end horizontal thrust, summarizes and puts forward fitting formulas respectively, providing reference for engineering design, especially in the stages of feasibility study, overall design and basic engineering design.

Key words: ultra-high pressure steam pipeline, stress analysis, CAESAR II software, fitting formula