Bolt Tightening Procedure

Posted in Pipe Flanges

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.

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.

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

Bolt Tightening Procedure Photos

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 - -

 

Bolt Tightening Sequence

Four Bolt

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

Data 4 bolt flange

Eight Bolt

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

Data 8 bolt flange

Twelve Bolt

  • 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 12 bolt flange

Sixteen Bolt

  • 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 16 bolt flange

Twenty Bolt

  • 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 20 bolt flange

Twenty Four Bolt

  • 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

Data 24 bolt flange