Abstract: The radial gap between the internal dynamic and static parts of the compressor in the ethylene plant is very small and sensitive to the external stress. If the compressor's connecting pipes are installed under stress, deformation or displacement of the body may occur. This in turn will cause change in concentricity between stator and rotor and then the occurrence of such problems as scraping between the rotor parts and static parts such as the spacer or air seal, coupling misalignment, bearing vibration and temperature overruns, and so on. Taking the installation of the compressor connecting pipes of an ethylene cracking plant as an example, this paper presents the methods to prevent the installation of the compressor connecting pipes under stress and the measures to relieve the residual stress in the compressor connecting pipes. This can be used as reference for the installation construction of connecting pipes of compressor unit under stress.

Key words: ethylene plant, pipe installation without stress, compressor body deformation, connecting the two sides of piping with closed section, stress relief