High-strength bolt connection sub-finish torque test instructions - Database & Sql Blog Articles

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This work instruction is used for the guidance of the high-strength bolt connection auxiliary construction torque inspection.

2 reference standard

GB50205 steel structure engineering construction quality acceptance specification

3 inspection timing

3.1 The final tightening torque test of the high-strength bolt connection sub-construction shall be completed within 1 hour after the screwing for 1 h.

4 inspection quantity

4.1 The number of inspections in the construction process shall be checked by 10% of the number of nodes, and shall not be less than 10 nodes; each of the spotted nodes shall be checked by 10% of the number of bolts, and shall not be less than two.

4.2 The number of witness inspections and inspections shall be carried out according to the requirements of Appendix G of GB50205, and 3% shall be checked according to the number of nodes, and shall not be less than 3 nodes.

5 test methods

5.1 The torque wrench used in the test shall have a torque accuracy error of less than 3%.

5.2 High-strength bolt connection The construction torque test is divided into initial screwing, double screwing and final screwing test; the inspection method is divided into two types: the torque method test and the corner method test. In principle, the test method and the construction method should be the same.

5.3 Torque test:

5.3.1 Dash the relative position of the screw end and the nut, and return the nut to about 60°;

5.3.2 Use a torque wrench to measure the torque value when screwing back to the original position and make a record.

5.3.3 Compare the deviation between the measured torque value and the construction torque value, and the deviation is within 10%.

5.4 Corner test:

5.4.1 Check whether the angle between the final starting line and the ending line drawn by the nut and the relative position after the construction is first screwed has reached the specified value.

5.4.2 Draw a line at the opposite end of the screw end and the nut, then loosen the nut completely, and re-tighten the bolt according to the specified initial tightening torque and final tightening angle to observe whether it overlaps with the original drawing line. The final twist angle deviation is within 10 °. The final twist angle is related to the diameter and length of the bolt and should be determined by experiment.

5.5 Twist-cut high-strength bolt construction torque test, observe that the tail of the plum blossom head is turned off as the final tightening torque to meet the eligibility criteria, those who have not been screwed off should be tested according to the above torque method or corner method.

6 calculation

The final tightening torque value of the high-strength bolt connection pair construction is calculated as follows:

Tc=K·Pc·d

Where Tc - final torque value (N · m);

Pc—standard value of construction pre-tension (kN), see Table 6.1 below;

D—the nominal diameter of the bolt (mm);

T0—The initial tightening torque value can be taken as 0.5Tc.

K-torque coefficient, determined according to the test of GB50205 Appendix B·0·4 (or by commissioned to provide high-strength bolt torque coefficient re-inspection report), the test see the high-strength bolt connection auxiliary torque coefficient re-inspection operation guidance. .

Table 6.1 Standard values ​​for pre-tensioning of high-strength bolted joints (kN)

Bolt performance rating

Bolt nominal diameter

M16

M20

M22

M24

M27

M30

8.8S

75

120

150

170

225

275

10.9S

110

170

210

250

320

390

High-strength bolt connection auxiliary construction torque range

Final torque value Tc=K.Pc.d

Initial tightening torque value T0=0.5Tc

Torque coefficient average K

0.110

~0.150

Kmax=0.15

Kmin=0.11

Torque value range

10.9S

Bolt nominal diameter M (mm)

16

20

twenty two

twenty four

27

30

Pre-tension

Pc

110

170

210

250

320

390

Final screw max

Tc

264

510

693

900

1296

1755

Final twist min

Tc

193.6

374

508.2

660

950.4

1287

Initially screwed max

T0

132

255

346.5

450

648

877.5

Initially min

T0

96.8

187

254.1

330

475.2

643.5

Torque value range

8.8S

Bolt nominal diameter M (mm)

16

20

twenty two

twenty four

27

30

Pre-tension

Pc

75

120

150

170

225

275

Final screw max

Tc

180

360

495

612

911.25

1237.5

Final twist min

Tc

132

264

363

448.8

668.25

907.5

Initially screwed max

T0

90

180

247.5

306

455.625

618.75

Initially min

T0

66

132

181.5

224.4

334.125

453.75