A comparative analysis of the two predictive models for OSV (Onset of Significant Vaporization) in forced convection boiling was conducted using CHF (Critical Heat Flux) database for water flow in uniformly heated vertical round tubes. As the results, a modified model that can predcit OSV more reasonably in a wide range of system parameters than the two existing models was proposed by combining them. A total of 8,984 CHF data points from 12 different published sources were used for this analysis, and their ranges of parameters were as follows: 1.01 ≤ P (pressure) ≤ 206.79 bar, 0.00102 ≤ D (diameter) ≤ 0.04468 m, 0.0254 ≤ L (length) ≤ 4.966 m, 9.92 ≤ G (mass flux) ≤ 18,619.39 kg/m²s, 0.113 ≤ q_c (CHF) ≤ 21.41 MW/m², -0.866 ≤ X (exit quality) ≤ 1.577. The modified OSV model is easy-to-use because it can calculate the Stanton number as function of G, D, C_p (specific heat) and k (thermal conductivity).