High-Strength Bolts and Nuts installation for Specification requirements
When we assemble a high-strength bolt connection pair, the side of the nut with a round table should face the chamfered side of the gasket. In general, when assembling a high-strength bolt connection pair with a large hexagon head, the chamfered side of the lower gasket of the bolt head should face the bolt head.
When installing high-strength bolts, the construction personnel should strictly prohibit the forced penetration of the bolts (in this case, such as hammering). If you cannot pass freely, you should use a reamer to trim the hole. The maximum diameter of the hole should be less than twice the diameter of the bolt after completion. When repairing holes, in order to prevent iron filings from falling into the seam of the board, tighten all bolts around the hole before reaming and check whether they are firm, so that the steel plate can be tilted tightly before operation. One of the places that need special attention is that gas cutting is strictly prohibited to enlarge the hole. The use of gas cutting and reaming is more likely to occur on site and requires special inspection.
There are two methods for establishing the pretension of high-strength bolts and nuts:
Torque method generally uses pointer torque (force) wrench or preset torque (constant force) wrench. At present, electric torque wrenches are more commonly used. The torque method controls the pre-tightening force by controlling the tightening torque. The tightening torque can be determined through experiments, and the pre-tightening force controlled during construction should be 1.1 times the pre-tightening force. When using electric torque to move the hand, the required construction torque tf is: where, pf is the construction preload force, which is 1 / 0.9 times of the preload force; k-the pre-construction retest torque given by the supplier Unified value of coefficient; D- diameter of high-strength bolt and nut.
In order to overcome the deformation of the plate and the washer, when installing high-strength bolts and nuts, the gap between the plate and the plate is eliminated, and the tightening torque coefficient has a good linearity, thereby improving the accuracy of the construction control preload value. First tighten with 50% tightening torque, then tighten with 100% tightening torque. After the initial tightening of the large joint, it should be tightened again according to the initial tightening torque, and then the final tightening.
Torque method is simple in strength, easy to implement and low in cost. However, due to the difference in the appearance of the connector and the joint and the tightening speed of the joint, the measured preload value is large and deformed, and the error is usually ± 25%.
Turning angle method is first tightened with a universal wrench to make the connection plate fit tightly. Then, starting from the initial tightening direction, use a long wrench or pneumatic wrench to turn the nut and tighten it to the viewpoint value. The tension of the bolt reaches the pre-tension of construction control.
Installation Method of Anchor Bolt
1. One-time embedding method: When pouring concrete, embed anchor bolts. When the tower is controlled by overturning, the anchor bolts should be buried once.
2. The reserved hole method: the equipment is in place, the holes are cleaned, the anchor bolts are placed in the holes, and the equipment is positioned and corrected, and then poured with non-shrinking fine stone concrete one level higher than the original foundation for tamping and compaction . The distance between the center of the anchor bolt and the edge of the foundation should not be less than 2d (d is the diameter of the anchor bolt), and should not be less than 15mm (d≤20 should not be less than 10mm), and not less than half the width of the anchor plate Add 50mm, when the above requirements cannot be met, appropriate measures should be taken to strengthen. The diameter of the anchor bolt used for the structure should not be less than 20mm. When subjected to earthquake action, double nuts should be used for fixing, or other effective measures to prevent loosening should be adopted, but the anchor length of anchor bolts should be increased by 5d compared to the non-seismic anchor length.
Planning the installation of anchor bolts. Handling of anchor bolts loose in the foundation. When tightening the anchor bolts, the bolts may be pulled out. At this time, the bolts should be adjusted to the original position, and the foundation around the bolts should be shoveled out of sufficient positions. Then, weld two U-shaped steel bars in the vertical and horizontal directions on the bolts, and finally clean and grouting the pit with water, wait for the concrete to solidify to the design strength, and then tighten the deviation of the live anchor bolts. The treatment method of the deviation of the live anchor bolts is roughly the same as dead. The method of anchor bolt is the same, except that the anchor bolt can be pulled out. If the bolt is too long, a section of thread can be cut off on the machine; if the bolt is too short, it can be extended by hot forging; if the position does not match, use the bending method to correct it.
Application industry is suitable for various equipment fixing, steel structure foundation embedded parts, street lamps, traffic signs, pumps, boiler installation, heavy equipment embedded fixing, etc.
The company sells: anchor bolts, stud bolts, tower bolts, embedded plates, hot-dip galvanized bolts, high-strength bolts and nuts, highway accessories, construction accessories and other products. The products are widely used in the construction engineering industry, sold well in the construction market all over the country, and exported to many places. The product quality is stable and reliable for a long time, and the service is professional and perfect.
Eternal Bliss Alloy Casting & Forging Co, Ltd.
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