Introduction  There are deviations in the design, manufacture and installation of the four major pipes building. These deviations have not caused great influence in the previous projects construction process, and are often easily ignored. With the optimization of the layout, the normal operating of the pipeline may be affected when various deviation trends are consistent, which needs to be studied.

  Method  We analyzed various common deviations between theoretical calculation and practical operation from the point of view of design, and we analyzed the influencing process of deviations in previous project.

  Result  The analysis results show that these neglected common deviations may affect the normal operation of the unit.

  Conclusion  The deviation between theoretical calculation and practical operation cannot be completely avoided, so it is necessary to pay enough attention to design, manufacturing and installation, feedback timely , control the impact of the deviation.