HIF - Studs, Bolts, and Tightening Bolt and Stud Requirements Use bolts or studs of SAE Grade 5 or better steel with rolled threads. Flat Washers are to be used under bolt heads and nuts. To achieve maximum torque loads, it is recommended that a high temperature anti-seize lubricant be applied to the bolt/studs before torquing. Bolt Torquing Procedures Tighten initially to approximately 2/3 of final torque using the alternate and opposite method. Tighten to the final torque shown in the table, again, using the alternate and opposite method. Repeat tightening to the final torque shown at least twice to ensure that flanges are permanently set. The final torque values should not be exceeded by more than 50%
Convert To Metric Units
Nominal Size (in.) # of bolts Bolt Dia. (in.) Bolt length pipe to pipe (passive to active) Bolt length fitting to fitting (passive to active) Initial torque (appox.) (ft/lbs) Final torque (minimum) (ft/lbs) 1 4 1/2 2 3/4 3 1/2 25 40 1 1/2 3 1/2 4 35 50 2 5/8 3 1/2 4 1/2 50 80 3 4 4 3/4 70 110 4 8 4 1/2 5 1/4 60 90 6 3/4 5 1/2 6 1/2 85 130 8 6 7 1/2 100 150
Tightening Sequence
4 Bolts or Nuts		8 Bolts or Nuts
Note: When using studs rather than bolts, increase the length sufficiently to allow for the additional length of a nut