Bolt Tightening Procedure
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.
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
Article Links
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 | - | - |
Four Bolt Tightening Sequence
- Sequential Order: 1-2, 3-4
- Rotation Order: 1, 3, 2, 4
Eight Bolt Tightening Sequence
- Sequential Order: 1-2, 3-4, 5-6, 7-8
- Rotation Order: 1, 5, 3, 7, 2, 6, 4, 8
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
sixteen 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
Twenty 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
Twenty 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
Bolt Tightening Datasheets
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