High-strength bolt process standards

Update time:28 Feb 2020

1 Materials and main equipment: 1.1 Bolts, nuts, and wa […]

1 Materials and main equipment:
1.1 Bolts, nuts, and washers shall be accompanied by a quality certificate and shall comply with the design requirements and national standards.
1.2 The high-strength bolts shall be stored according to the specifications when stored, and shall be protected from rain and moisture. In case of unmatched bolts and nuts, do not use when the thread is damaged. The bolts, nuts, and washers are rusted, and the tightening axial force should be checked by sampling, and can be used only after meeting the requirements.
Bolts and the like must not be contaminated by dirt and oil, and kept clean and dry. It must be used according to the batch number in the same batch, and cannot be mixed or used.
1.3 Main tools: electric torque wrench and controller, manual torque wrench, manual wrench, wire brush, tool bag, etc.
2 Operating conditions:
2.1 Friction surface treatment: The friction surface is treated by sand blasting, wheel grinding, etc. The friction coefficient should meet the design requirements (a requirement is that Q235 steel is above 0.45, and 16 manganese steel is above 0.55). Residual oxide scale is allowed on the friction surface wood. After processing, the friction surface can generate red rust surface and then install bolts (usually stored in the open for about 10 days). The friction surface treated with sandblasting can be installed without rust. When grinding with a grinding wheel, the grinding range should be no less than 4 times the bolt diameter, the grinding direction should be perpendicular to the direction of the force, and the friction surface after grinding should not be significantly uneven. The friction surface is protected from oil or paint contamination, such as contamination should be completely cleaned.
2.2 Check the hole size of the bolt hole. The burr on the edge of the hole must be removed.
2.3 Bolts, nuts, and washers of the same batch number and specifications should be packed together for use.
2.4 Electric wrenches and manual wrenches should be calibrated.

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