Abstract: An analysis on the vertical turning point used in the equations for the pipe laying with elastic bending is carried out. It is pointed out that a critical value exists under a certain curvature radius. For the value, there are obvious differences when it is respectively used in oil pipeline and gas transmission pipeline. Therefore, the two equations used to calculate the curvature radius of pipe showed in two Stated Standards are compared, and a derivation is made according to the flexibility beam principle of steel structure. The simplified equation to calculate the critical value of vertical turning point for the pipe laying with elastic bending is obtained.