The torque tables are built on specific assumptions regarding bolt and nut factor. Before using a given torque table, these assumptions should be verified to insure they are appropriate for the specific application.
Even if all assumptions are appropriate, results may vary depending on actual conditions. Many factors induce scatter in the results or increase the inherent variability in the bolting process. These include variations in the nut factor; bolt, flange and nut condition; equipment calibration and condition; perpendicularity of the bolt, nut and flange; etc.
The values in the tables are based on the equation