Regardless of the type of torque wrench (hydraulic, electric or pneumatic) used, a flange connection is tightened in 4 steps. This is done in a cross-tightening sequence in which the bolts are torqued.
Stap 1: Step 1: Tighten 4 threaded rods to 30% of the specified torque according to the tightening sequence.
Stap 2: Step 2: Install all threaded ends to 60% of the specified torque according to the tightening sequence.
Stap 3: Step 3: Apply the specified torque according to the tightening sequence.
Step 4: This is a checking step in which all threaded ends are tightened again to the specified torque, this time not crosswise but bolt by bolt counterclockwise. When the nuts no longer turn, the threaded ends are torqued. If this is not the case, repeat step 4.
Example flange tightening sequence:
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