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Manufacturing process of Steel structural members (3)

Jul 02, 2018

3. Construction of high strength bolts

3.1 preparation before installation

1) Test and test of high strength bolt

1.1 slip resistance coefficient test

In this project, 10.9 grade large hexagonal high strength bolts are adopted. The test of slip coefficient of high strength bolts should be carried out by taking the most representative thickness plate in the project and doing three groups

1.2 Axial Force Test

Random sampling of bolt batches to be installed in the construction site, 8 sets of bolt pairs for reinspection in each batch.

2) Transport and storage of high strength bolts

2.1 Transport

The form, size and technical conditions of the high strength bolt connection pair shall be in accordance with the national standards GB1228-1231-84 and GB3632-3633-83. The steel structure is composed of a bolt, a nut and two washers. The use and combination shall conform to the national standard and the high strength bolt connection pair shall be supplied with storage and transportation in the same batch. High strength bolt connection pair in the loading, unloading and transportation and storage process to light loading, light release, to prevent damage to the packaging box, damage bolts.

2.2 High strength Bolt Warehouse custody

2.2.1 the high strength bolt connection pair shall be cleaned according to the specification, lot number and number of the name of the packing case, the date of supply shall be cleaned up, stored in classified storage, stored in an indoor warehouse, not more than 3 storeys, and indoor moisture-proof, Keep dry for a long time, prevent rust and dirt, prevent torque coefficient from changing. The bottom layer should be more than 300mm above the ground height.

2.2.2 the installation at the site shall be issued in accordance with the number of high strength bolts required for the day. Take good care of the rest. Do not put, damage thread, contaminated by dirt.

2.2.3 before the long-term storage of the high strength bolt connection pair, it is necessary to make a comprehensive quality inspection again, and also to inspect the abnormal phenomenon found after opening the box, and the inspection standard shall be carried out in accordance with the relevant provisions of the national standards GB1228 / 1231-84 and GB3632 / 3633-83. It can be used after qualification.

3) Construction Management of High strength Bolt

3.1 Construction managers

In the construction of the high strength bolt, the manager of the high strength bolt is first determined to be the project management, quality management and guide construction personnel.

3.2 Weather management (climatic conditions)

Rain, snow in principle do not carry out the operation, if rain, snow in the operation, should accelerate the speed of the unscrewed lock up

3.3 friction surface management

Before tightening, the friction surface is checked first, and if there are some attachments to reduce the bearing capacity of friction surface, such as floating rust, oil, paint, residue, so on, the metal brush, sandpaper and oxygen gas-acetylene flame are used to remove them.

4) Construction of high strength bolt

4.1 the final twist of temporary bolts 

4.1.1 before the insertion of high strength bolts, in order to make the connection tight with temporary bolts, the material in the connection area should be corrected if there is a bending or warping. 

4.1.2 when the hole difference is within 2mm, the cutter can be used to correct the difference. 

4.1.3 if the difference between the holes exceeds 2 mm, on the basis of consultation with the management, reasonable treatment methods, such as changing the splice plate, are adopted, and the gas cutting reaming is not allowed.

4.2 High strength bolt inserts

4.2.1 the nuts and gaskets of high strength bolts should be installed with attention to the direction of installation and install according to the figure below. 

4.2.2 when inserting bolts, be careful not to attach rust, dust, oil, etc. In addition, do not force into the bolt hole in order to avoid damage to the thread.

4.3 initial screwing

4.3.1 confirm the density of the member after locking the temporary fixed bolt. 

4.3.2 after first twist, mark with white marker through bolts, nuts, gaskets and components

Bolt initial screw.jpg

4.3.3 is marked with a white marker through bolts, nuts, gaskets, and components, the torque value can be confirmed by contact sound, but it is easy to wring strength if the force continues on the mechanism. Please note.Special wrench for bolt of steel structure.jpg

4) end twisting

4.1 after the first twist, use a special fastening wrench for locking until the necking is broken. 

4.2 the bolts inserted on the day shall in principle be screwed at the end of the day. 

4.3 the final screw is, in principle, from the center to the end of the joint.

5)construction process of high strength bolt

Construction process of High strength Bolt.jpg