IN–42 INTRODUCTION – STANDARD BOLT TORQUE SPECIFICATIONS STANDARD BOLT TORQUE SPECIFICATIONS HOW TO DETERMINE BOLT STRENGTH Mark | Class | Mark | Class Hexagon head bolt 4 – 4T 5 – 5T Bolt 6 – 6T head No. 7 – 7T 8 – 8T 9 – 9T 10 – 10T 11 – 11T No mark 4T Stud bolt No mark 4T Hexagon flange bolt w/ washer hexagon bolt No mark 4T Grooved 6T Hexagon head bolt 2 protruding lines 5T Hexagon flange bolt w/ washer hexagon bolt 2 protruding lines 6T Welded bolt Hexagon head bolt 3 protruding lines 7T 4T Hexagon head bolt 4 protruding lines 8T