SEQUENCE FOR FLANGES USING 20
Lubricate bolt and nut threads and nut
bearing face (where it contacts the flange).
After flange assembly and all nuts have
been run down by hand, start wrench tightening following the
sequence of the numbers indicated (marking the number on the
flange with a crayon aids in keeping track of the tightening
During all of the following steps, keep
any gap between flanges even all around the circumference, and
nuts made up approximately the same amount on each end of the
First time around just snug the nuts with
a hand wrench.
Second time around tighten the nuts
firmly with the same wrench.
Third time around apply approximately 25% recommended
Fourth time apply approximately 75% of recommended
Fifth time around, apply 100% of
Continue tightening nuts all around until
nuts do not move under 100% recommended torque.
If possible, re-torque after 24 hours.
Most of any bolt preload loss occurs within 24.