0-15 STANDARD BOLT & NUT TIGHTENING TORQUE Standard bolt and nut tightening torques are not indicated. Judge the standard tightening torque as shown below. 1. For tightening torque of hexagon head bolt, welded bolt and stud bolt with the standard bearing surface, identify bolt class based on the below chart and then determine using the tightening torque table. 2. For tightening torque of hexagon flange bolts, identify bolt class based on the below chart and then determine using the tightening torque table. 3. For tightening torque of nuts, check the mating bolt and use the method 1.
BOLT STRENGTH CLASS IDENTIFICATION METHOD Identification by Bolt Shape Shape and class Class Hexagon head bolt Bolt head No. 4 = 4T 5 = 5T 6 = 6T 7 = 7T 8 = 8T No mark 4T Two protruding lines 5T Three protruding lines 7T Four protruding lines 8T Welded bolt 4T Stud bolt No mark 4T Grooved 6T