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Bolt Tightening Procedure

 

Bolt Tightening Datasheets

data bolt machine

data bolt stud 

bolt circle 1

General Guidelines that can be Followed 

Bolt tightening procedures are typically specific to the application and the type of bolt being used.

  • Use the correct torque specifications provided by the manufacturer for the particular bolt and application.
  • Lubricate the threads and the contact surface of the bolt and nut with an appropriate lubricant.
  • Tighten the bolts in a star pattern, tightening each bolt a little at a time to ensure that the load is evenly distributed.
  • Use a calibrated torque wrench or tensioning device to achieve the correct level of bolt tension.
  • Verify the torque or tension after a specified time has elapsed or after a specified number of cycles.

It is important to note that these general guidelines may not be sufficient for all applications, and that specific bolt tightening procedures should be followed for each application.  Additionally, it is important to consider the environment and any safety factors that may be relevant to the application.
Start the tightening procedure by lubricating the nuts and bolts.  Then hand tighten till they are snug against the flanges.  If an air wrench is used make sure the pressure is set to the minimum.  When tightening, always use the correct sequential bolt order for the flange.

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ANSI Class Torque Factor

  Pipe Size  

(NPS)

150#

  (ft-lbs)  

300#

  (ft-lbs)  

400#

  (ft-lbs)  

600#

  (ft-lbs)  

900#

  (ft-lbs)  

1500#

  (ft-lbs)  

2500#

  (ft-lbs)  

1/2 45 45 45 45 150 150 -
3/4 45 90 90 90 150 150 -
1 45 90 90 90 240 240 -
1 1/4 - - - - - - -
1 1/2 45 150 150 150 368 368 -
2 90 90 90 90 240 240 -
2 1/2 90 150 150 150 368 368 -
3 90 150 150 150 240 533 -
3 1/2 - - - - - - -
4 90 150 240 240 533 750 -
5 150 150 240 368 750 1200 -
6 150 150 240 368 533 1020 -
8 150 240 368 533 1020 1650 -
10 240 368 533 750 1020 3000 -
12 240 533 750 750 1020 3300 -
14 368 533 750 1020 1020 4770 -
16 368 750 1020 1020 1650 6600 -
18 533 750 1020 1650 3000 8800 -
20 533 750 1200 1650 3300 11580 -
22 - - - - - - -
24 750 1200 2250 3000 6600 - -

4 and 8 Bolt Flanges 

  • First round - 30% of final torque (flange sequential order)
  • Second round- 60% of final torque (flange sequential order)
  • Third round - 100% of final torque (flange sequential order)
  • One final time - clockwise or counter clockwise sequentially around the flange.

12 Bolt Flanges and More 

  • First round - 20% of final torque (flange sequential order)
  • Second round - 40% of final torque (flange sequential order)
  • Third round - 80% of final torque (flange sequential order)
  • Fourth round - 100% of final torque (sequential order)
  • One final time - clockwise or counter clockwise sequentially around the flange.

Bolt Standards 

  • ASME Standards
    • ASME PCC-1 - Guidelines for Pressure Boundary Bolted Flange Joint Assembly
  • ISO Standards
    • ISO 4162 - Hexagon bolts with flange - Small series - Product grade A with driving feature of product grade B
    • ISO 15071 - Hexagon bolts with flange - Small series - Product grade A
    • ISO 15072 - Hexagon bolts with flange with metric fine pitch thread - Small series - Product grade A
    • ISO 21670 - Fasteners - Hexagon weld nuts with flange

Data 4 bolt flangeFour Bolt Tightening Sequence

  • Sequential Order: 1-2, 3-4
  • Rotation Order: 1, 3, 2, 4

 

 

 

 

Data 8 bolt flangeEight Bolt Tightening Sequence 

  • Sequential Order: 1-2, 3-4, 5-6, 7-8
  • Rotation Order: 1, 5, 3, 7, 2, 6, 4, 8

 

 

 

 

Data 12 bolt flange

Twelve Bolt Tightening Sequence 

  • Sequential Order: 1-2, 3-4, 5-6, 7-8, 9-10, 11-12
  • Rotation Order: 1, 5, 9, 3, 7, 11, 2, 6, 10, 4, 8, 12

 

 

 

 

Data 16 bolt flangeSixteen Bolt Tightening Sequence 

  • Sequential Order: 1-2, 3-4, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16
  • Rotation Order: 1, 9, 5, 13, 3, 11, 7, 15, 2, 10, 6, 14, 4, 12, 8, 16

 

 

 

 

Data 20 bolt flangeTwenty Bolt Tightening Sequence 

  • Sequential Order: 1-2, 3-4, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, 19-20
  • Rotation Order: 1, 9, 5, 13, 3, 11, 7, 15, 2, 10, 6, 14, 4, 12, 8, 16

 

 

 

 

Data 24 bolt flangeTwenty Four Bolt Tightening Sequence 

  • Sequential Order: 1-2, 3-4, 5-6, 7-8, 9-10, 11-12, 13-14, 15-16, 17-18, 19-20, 21-22, 23-24
  • Rotation Order: 1, 9, 17, 5, 13, 21, 3, 11, 19, 7, 15, 23, 2, 10, 18, 6, 14, 22, 20, 8, 16, 24

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