15
IOM-5400
ADDENDUM - A
TIGHTENING SEQUENCE FOR FLANGE BOLTING
GUIDELINES FOR BOLTED FLANGE JOINT ASSEMBLY ACCORDING TO ASME PCC-1 SPECS
STEP
LOADING
Install
Hand tighten. Check flange gap around circumference for uniformity. If the gap is not reasonably
uniform, make the appropriate adjustments by selective tightening before proceeding.
Round 1
Tighten to 20% to 30% of target torque. Check flange gap around circumference for uniformity. If
the gap is not reasonably uniform, make the appropriate adjustments by selective tightening before
proceeding.
Round 2
Tighten to 50% to 70% of target torque. Check flange gap around circumference for uniformity. If
the gap is not reasonably uniform, make the appropriate adjustments by selective tightening before
proceeding.
Round 3
Tighten to 100% of target torque. Check flange gap around circumference for uniformity. If the gap
is not reasonably uniform, make the appropriate adjustments by selective tightening.
