Today, we will introduce the specifications for bolts, nuts, and washers from the aspects of bolt connection, assembly, fastening, use position, and direction of penetration.
Basic requirements for bolt connection
Ordinary bolts shall meet the following requirements when used as permanent connecting bolts:
1. For general bolt connections, flat washers should be placed under the bolt heads and nuts to increase the pressure bearing area.
2. Flat washers should be placed on the bolt head and nut side respectively. Generally, there should be no more than two flat washers on the bolt head side, and no more than one flat washer should be placed on the nut side.
3. For bolts and anchor bolts that are designed to require anti-loosening, nuts or spring washers with anti-loosening devices should be used, and the spring washers must be installed on one side of the nut.
4. For bolt connections that bear 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.
5. For I-beam and channel steel type steels, inclined washers should be used when connecting with inclined planes, so that the bearing surface of the nut and bolt head is perpendicular to the screw.
Bolt use position classification requirements
According to the use position and function of the bolts of the distribution line, bolts can be divided into three types: electrical connection, electrical equipment fixing, and iron accessory fixing. The following is a specific description:
1. Electrical connection: The outdoor primary wiring should be connected by hot-dip galvanized bolts. The bolts used should have flat washers and spring washers. After the bolts are tightened, the bolts should be exposed by 2 to 3 buckles. One bolt is equipped with two flat washers, one spring washer, and one nut. When installing, place a flat washer on the head side of the bolt, and place a flat washer and a spring washer on the nut side. The spring washer rests on the nut.
2. Electrical equipment fixing category: transformers, distribution box bases and iron accessories are connected. For example, when channel steel beveled bolts are used for fixing, one bolt is equipped with a nut, a bevel washer (for channel steel bevel side) and a flat washer (for flat surface). 2 side use). When using channel steel flat bolts to connect and fix, one bolt is equipped with two flat washers, one spring washer, and one nut. When installing, place a flat washer on the head side of the bolt, and place a flat washer and a spring washer on the nut side. The spring washer rests on the nut. In principle, use the mounting bolts provided by the equipment manufacturer to connect the isolating switch, drop-out fuse, arrester and iron accessories.
3. Iron attachment fixing type: when the iron attachment bolt hole is round, one bolt is equipped with a nut and two flat washers; when the iron attachment bolt hole is a long hole, one bolt is equipped with a nut and two square washers , When installing, place a flat washer (square washer) on the bolt head side and the nut side. When the iron attachment is connected with stud bolts, each end of the bolt is equipped with a nut and a flat washer (square washer). For the bolt connection on the inclined surface of channel steel and I-beam flange, use inclined washers as far as possible to make the bearing surface of the nut and bolt head perpendicular to the screw.
Bolt threading requirements
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: along the line direction, double-sided components from the inside to the outside, and single-sided components penetrate from the power transmitting side or in a uniform direction; in the horizontal line direction, the two sides are from the inside to the outside, and the middle is from left to right (facing the power receiving side) Side) or in a uniform direction; vertical direction, from bottom to top.
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 low voltage terminal to the high voltage terminal; take the transformer and the pole as the reference direction, pass from the transformer side to the pole side (from the inside to the outside) Put on).
Bolt tightening requirements
The connecting bolts should be tightened one by one, and the tightening torque of the bolts should not be less than the stipulations in the table below. If it is found that the thread of the screw and nut has sliding teeth or the edges and corners of the nut are worn so that the wrench slips, the bolt and nut should be replaced.