The painting of structures after crypts and disassembling the part is finally painted with oil paint in one or another color at the direction of the customer. To facilitate sorting when installing parts at the installation site, all of them after painting at the factory manufacturing structures are marked, t. e. each part is assigned a certain number or letter designation. This brand is applied with white paint in a prominent place.
Staining structures
This ends the process of manufacturing structures at the factory. The remaining seven operations following the manufacture of structures listed at the beginning of the fourth chapter belong to the installation of structures and are set out in the second part of this work. Recently, welding quickly gains a prominent place in the process of manufacturing metal structures.
The development of this method of compounds should be attributed to the time of improving electric arc welding, first invented inzh. Slavyanov in 1891. Currently, two methods are used for electric welding of metal structures: the first is welding with resistance, or hot welding, and the second is welding with a voltage arc, or arc (cold) welding.
The principle of welding by the first method is as follows. The welded elements are located between two copper electrodes. Then, through these electrodes and the welded elements, the electrical current of very large power, but of small voltage (about 1000 amperes at a voltage of 5-10 volts) is passed through them.
When an electric current passing through the welded elements heats the material to the temperature of white heat, the electrodes with the help of a special device compress the welded parts with great force. Under the influence of this pressure, the material is welded, after which the current is interrupted, and the welding ends. To carry out a continuous welding line, electrodes are constructed in the form of rollers, slowly rotating and compressing material with sufficient by force.