Basic requirements for bolt connection 

Ordinary bolts should meet the following requirements as permanent connection bolts: 

1. For general bolt connections, flat washers should be placed under the bolt head and nut to increase the pressure-bearing area. 

2. Flat washers should be placed on the bolt head and the nut side respectively. Generally, there should be no more than 2 flat washers placed on the bolt head side, and there should be no more than 1 flat washer placed on the nut side. 

3. For bolts and anchoring bolts designed with anti-loosening requirements, nuts or spring washers with anti-loosening devices should be used, and the spring washers must be set on one side of the nut. 

4. For bolt connections bearing dynamic loads or important parts, spring washers should be placed according to design requirements, and spring washers must be set on one side of the nut. 

Five. For I-beam and channel steel types of steel, oblique washers should be used when connecting with a slope, so that the support surface of the nut and bolt head is perpendicular to the screw. 

Classification requirements for bolt use position 

 According to the location and function of distribution line bolts, bolts can be divided into three types: electrical connection category, electrical equipment fixing category, and iron accessory fixing category. The following is a specific explanation: 

1. Electrical connection category: Outdoor primary wiring should be connected by hot-dip galvanized bolts, and the bolts used should have flat washers and spring washers. After the bolts are tightened, the bolts should be exposed to 2 to 3 buckles. One bolt with two flat washers, a spring washer and a nut. During installation, a flat washer is placed on the head side of the bolt, and a flat washer and a spring washer are placed on the side of the nut, in which the spring washer is against the nut. 

2. Electrical equipment fixing category: When the transformer, distribution box base and iron accessories are connected and fixed by channel steel bevel bolts, one bolt is equipped with a nut, an oblique washer (for channel steel slope side) and a flat washer (for plane 2 sides). When fixed with channel steel flat bolt connection, one bolt is equipped with two flat washers, one spring washer and one nut. During installation, a flat washer is placed on the head side of the bolt, and a flat washer and a spring washer are placed on the side of the nut, in which the spring washer is against the nut. In principle, the connection of isolation switches, drop-type fuses, lightning arresters and iron accessories uses the installation bolts provided by the equipment manufacturer. 

3. Iron accessory fixing category: When the iron accessory connection bolt hole is a round hole, one bolt is equipped with a nut and two flat washers. When the iron accessory connection bolt hole is a long hole, one bolt is equipped with a nut and two square washers. During installation, a flat washer (square washer) is placed on the bolt head side and the nut side. When the iron accessory is connected with bolts, each end of the bolt is equipped with a nut and a flat washer (square washer). For the bolt connection of the inclined surface on the wing edge of the channel steel and the I-beam, try to use an oblique washer so that the support surface of the nut and bolt head is perpendicular to the screw. 

The penetration requirements of the bolt 

1. For the three-dimensional structure: the horizontal direction is from the inside to the outside; the vertical direction is from the bottom to the top. 

2. For the plane structure: in the direction of the line, the double-sided component is from the inside to the outside, and the single-sided component is inserted from the transmission side or in a unified direction; the horizontal line direction, from the inside to the outside on both sides, and the middle is from left to right (facing the receiving side) or in a unified direction; in the vertical direction, from the bottom up. 

3. The plane structure of the transformer stand: take the high and low voltage terminals of the transformer as the reference direction, and pass from the end of the low-voltage terminal to the direction of the high-voltage terminal; take the transformer and the pole as the reference direction, pass from the side of the transformer to the side of the pole (from the inside to the outside). 

Tightening requirements of bolts 

The connecting bolts should be tightened one by one, and the torque of the bolt should not be less than the provisions of Table 4. If it is found that the thread of the screw and the nut has slip teeth or the edges of the nut are worn and the wrench slips, the bolts and nuts should be replaced. 

Bolt assembly 

1. Visually check the thread holes of the bolts, nuts or connectors before assembly. There should be no bumps or scratches, and meet the standards cited in the drawings or this specification. 

2. During the assembly process, do not touch the threaded part of the bolt. 

3. The head of the bolt and the washer at the end of the nut should be in uniform contact with the plane of the fastened part. It should not be tilted, and it is not allowed to knock the two planes with a hammer. The screw should not be bent and deformed. 

4. The connected parts should be evenly pressed, closely fit each other, and firmly connected. 

5. It is strictly forbidden to use inappropriate wrenches when tightening bolts and nuts. 

6. When assembling bolts and screws, you should screw in more than 2 to 3 pitches by hand, and then tighten them with a wrench or electric tool. 

7. When assembling bolts and nuts, pay attention to protect the paint film, plating and bolt and nut heads of the connected parts so as not to be damaged. 

8. After the nut is tightened, the bolt head should be exposed to 2 to 3 pitches at the end of the nut, and the nut and washer should face the connector on the reverse side (the side marked with the words of the nut is the front, and the smooth side of the washer is the front). 

9. After the bolt is tightened, paint the mark, and the marking position is generally dotted with red paint at the contact point between the bolt and the nut. The color can be changed according to the place of use, but the color must be clearly distinguished.