Welding process of self-shielded flux cored wire

Construction and welding = self-shielded flux cored wire welding process. Per Petroleum Bureau of Mechanical Engineering, Provincial and Municipal Government 736. It is used in wood to improve the quality of pipeline engineering construction. Welding quality has adopted self-shielded flux cored wire welding in line construction. 1 Overview The key to the quality control of the pressure pipeline installation project depends on the quality of the welding seam, how to control this key link. In addition to strengthening the on-site quality control technology, we also need to strengthen the welding equipment. Welding materials. The management and application of welding technology and welding technology to protect the flux core 1. The welding performance of the wire is stable, and the welding quality is reliable. The weld formation is better. With the development of welding technology, it will be widely used in Shanghai Fu line technology construction.

Qinghai Oilfield Yandun Natural Gas Line has a total length of 51 mm, a diameter of 323.9, and a pipe with a diameter of 52. Both use cellulose slave strips and Baibaojie flux-cored wire downward welding technology and welding technology to achieve good welding quality. . In order to develop the application of inner-shielded flux cored wire in pipeline design, the characteristics and application of 9-shielded flux-cored wire downward welding technology are introduced.

2 Welding characteristics of self-shielded flux cored wire ⑴ The alloy chemical agent of self-shielded flux cored wire is placed in the metal tube sleeve. In the use process, it is very different from other welding materials. It does not need to add any protective gas or flux to protect and flood.

2 The welding operation is simple and suitable for welding in all positions. Reduce welding joints. Improve welding efficiency.

Self-shielded welding uses flux-core protection, which has a high deposition rate. The self-shielded welding flux-cored wire has good weldability. It has the environmental resistance and wind resistance comparable to manual arc welding. It is wild. One of the good welding materials for pipeline construction.

3 Preparations for welding ⑴ Welding equipment should be selected for inspection and maintenance before welding, to ensure that the welding equipment is in good condition, and to provide protection for the application 1.

2 Bake the welding materials used. The baking temperature of the cellulose electrode should be less than or equal to 300350 flux cored wire, and the dried consumables should be kept warm so that they can be taken as needed.

Debris such as oil rust and dirt in the enclosure affects the welding quality.

Do a good job of two tubes and one set of quality control = general bevel angle is 6075, blunt edge is 1.01.5 Yang and Yang, the gap between the counterparts is 1.0 positioning welding root welding, use internal and external one set. Perform root welding after the counterpart meets the quality requirements. According to the size of the pipe diameter, determine the number of welders to be welded. For pipes greater than or equal to 73, 3 white shielded flux cored wire can be used in half and 1 to be fully automatic welding. , Turn around, cell, stop talking, grate him, and weld to 6 o'clock. When the root welding exceeds 2 perimeter of the pipe, the counterpart can only be detached.

4 Welding process requirements and operation points 4.1 When welding the button, the arc can be extinguished when the welding gun is withdrawn from the weld bead.

3 Determine the tilt angle of the welding torch. The inclination angle of the welding torch and the forward direction 2. The inclination angle is directly related to the melting and appearance molding. If the slag is to lead the arc, try to increase the tilt angle. However, if the inclination is too large, it will destroy the arc's protection and cause defects.

Cellulose electrode is used for welding and root welding, and the filling cover is made of self-shielded flux cored wire. Welding sequence 1. The number of welding layers is determined according to the wall thickness of the pipe.

4.2 Welding process parameters Welding process parameters should be selected 1.

When welding, in addition to considering the above requirements, at the same time, we must strictly follow the specification requirements to set the welding voltage and select a reasonable welding speed. Due to the high deposition speed of flux-cored wire, too high or too low will lead to welding defects and bad welds. The control of the welding voltage can be adjusted by the knob of the welding machine panel. During the welding process, when the arc is interrupted and the arc needs to be re-started, the arc stop should be repaired and the dry elongation part removed.

Welding layer name Welding material grade Weld number of welding wire diameter mm Welding current voltage welding speed 塍 speed root welding cellulose-filled flux-cored welding wire cover flux-cored welding wire , When welding, the arc is drawn on the groove surface of the arc starting plate, and the straight pull swings slightly. The arc length is controlled between 3.05. And 1. The welding is performed by two welders from 12 o'clock clockwise to 6 o'clock. For welding, each welder must lead the arc forward and backward 15 when starting and ending the arc. When replacing the electrode, the arc should be mechanically polished into a ramp. When welding continues, the electrode should be pushed forward quickly and pulled back to preheat the arc starting point to continue normal welding. Because the protective gas released by the coating of the cellulose electrode is earlier, the molten iron in the molten pool is slightly thicker, and the melting performance is good. During root welding, the quality of the back of the welding seam is high. But be careful. The drying temperature of the cellulose electrode should not exceed 100. If the arc is interrupted during arc welding, the electrode should be replaced.

4.3.2 Use mechanical methods to remove the debris and other debris from the root welding seam before welding on the filling cover. After confirming the qualification, perform welding.

When welding, use the button on the welding gun to set the dry elongation, usually keep the dry elongation at 15, 20, after determining the dry elongation, move 5 Points to note during the welding process The flux-cored welding wire can be self-protected for spin welding The rate is high, the meltability is good, and good welding quality can be obtained. Once the principle that violates the welding specification is not ignored, the problem of affecting the welding quality will also occur. There are many factors that affect the quality of welding. The following is a brief introduction to several typical factors.

The main cause of poor weld formation is that the voltage is too long and the elongation is too long, the wire feeding speed and welding speed are too fast, and the welding wire inclination is too large.

The reason for the blowhole defect is that the welding wire is corroded by moisture, the welding wire is short, the welding wire inclination is too large, the welding speed is too high, etc. will be affected.

The occurrence of arc deviation should be adjusted and controlled according to the welding position, changing the operation method, reducing the welding wire inclination angle, increasing the dry elongation, reducing the voltage and welding speed, etc.

6 Conclusion Through the practical application of self-shielded flux cored wire, it fully reflects the superiority of flux cored wire, because it has continuous wire feeding welding, reducing welding joints, thereby improving welding quality and welding efficiency. With China's upcoming accession and the implementation of the Western Development Strategy, engineering construction is gradually transformed into an international legal system track, the quality of engineering construction is higher and stricter, and the welding method of self-shielded flux cored wire will play an important role in pipeline construction. .

Received date December 25, 2000; revised date August 2, 2001