With the increase in parameters and capacity of newly built coal-fired units

the expansion of critical long-distance and large-diameter pipelines due to high parameters becomes more significant

making the design of supports and hangers particularly important. In a case involving a 2×660 MW ultra-supercritical unit

the diagonal brace of a rigid hanger tripod supporting the main steam pipeline buckled

resulting in a pipeline subsidence of nearly 130 mm. A comprehensive inspection of the pipeline supports and hangers was conducted

along with mechanical analysis of the statically indeterminate tripod structure and stability analysis of the diagonal brace. The study concluded that the failure of the diagonal brace and the pipeline sinking were primarily caused by an incorrect design of the radial horizontal restraint gap. Additionally

the excessive constant force of the constant hanger also contributed to the damage of the diagonal brace. This research not only analyzed the design flaws of the pipeline supports and hangers

but also proposed an engineering solution to optimize the restraint gap

which was validated on-site. A rectification plan involving horizontal limit adjustment and pipeline lifting was developed and implemented

successfully restoring the pipeline to its designed state and resolving the issue. This problem is highly representative in the construction of large-scale power units and should draw the attention of designers to avoid similar issues in future projects.