When the strength of the welded steel pipes is determined after the strength of the welding rod is determined, it is mainly determined by the complexity of the specific shape of the welded structure, the thickness of the steel, the load of the weldment (static or dynamic load) and the resistance of the steel. Cracking and the difficulty of getting a DC power supply. Generally speaking, the requirements for plasticity, impact toughness and crack resistance are high. For the welds working under low temperature conditions, basic welding rods should be used; when limited by certain conditions, the rust at the groove of low carbon steel weldments cannot be cleaned. . For dirt such as oil stains and scales, acid rods with low sensitivity to rust, oil stains and scales and strong anti-porosity properties should be used.
Welding of dissimilar steel of welded steel pipes, such as low carbon steel and low alloy steel, and low alloy steel of different strength grades, generally use welding rods matched with steel of lower strength grade.
(1) Working conditions and performance of the weldment. Pearlitic heat-resistant steel is generally selected from electrodes with similar chemical composition to the steel, or according to the operating temperature of the weldment.
(2) Simplify the process, increase productivity and reduce costs.
(3) Selection of electrode diameter. The choice of electrode diameter depends on factors such as weldment thickness, joint type, weld location and weld level. In order to improve labor productivity without prejudice to the quality of welding, it is generally preferred to select large diameter electrodes.
(4) Selection of welding current of welded steel pipe. It is mainly determined by factors such as the type of welding rod, the diameter of the welding rod, the thickness of the weldment, the joint type, the weld space position and the welding level. The most important factors are the diameter of the welding rod and the position of the weld space.
(5) Selection of arc voltage. The arc voltage is determined by the length of the arc. When the arc is long, the arc voltage is high; when the arc is short, the arc voltage is low.
(6) Selection of the number of welded steel pipe layers. Multi-layer welding is often used in arc welding of medium and heavy plate electrodes.
(7) Selection of power source type and polarity. DC power supply, stable arc, small splash, good welding quality, generally used in the welding of important welded structures or thick plates with large stiffness structure. In other cases, the AC welder should be considered first.
In general, the welding of alkaline electrodes or sheets is performed by DC reverse connection, while the acid electrodes are usually connected.
(1) When the carbon arc planer is working, only the AC and DC arc welders are needed, and no air compressor is needed.
(2) Submerged arc welding materials.
(3) Welded steel pipe flux Submerged arc welding flux is divided into steel flux and non-ferrous metal flux according to the application, and is divided into smelting flux, sintering flux and ceramic flux according to the manufacturing method.