Application of Pipe Automatic Welding Machine in Construction of Long Distance Pipeline

First, the characteristics of welding in the construction of long-distance pipelines

1. The effect of fluidity construction on welding quality. The construction work points continue to migrate along with the construction progress. Compared with the production of the factory products, the construction management, quality management, safety management and other aspects are more difficult; because the welding operation is in a flowing state, the quality is relatively difficult to ensure.

2. The influence of topography on welding quality. The construction unit does not have the ability to choose the ideal construction site. A long-distance pipeline may encounter a variety of terrains, such as the West-East Gas Transmission Project, from the west to the east through the Gobi, desert, Loess Plateau, mountainous areas, plains, water networks, etc. The topography and geomorphology have a direct impact on welding, so it is necessary to adapt to local conditions. Choose different welding methods to meet the needs of the project.

3. The impact of the environment on the quality of the weld. The natural environment such as wind, rain, temperature and humidity has a certain relationship with the quality of welding.

4. In addition to on-site double-tube welding, factors such as welding equipment, processes, materials and welder skills have a great impact on welding quality.

5. The influence of humanities and social environment on welding quality. In the artificially dense areas of eastern China, due to various reasons, the construction cannot be carried out continuously, which often brings difficulties to on-site welding. Due to external factors, the number of heads on the site is increased, the number of joints is increased, the quality is difficult to guarantee, and the welding cost is also increased.

Second, the status of pipeline welding

With the advancement of social technology, long-distance pipeline welding technology is gradually improving.

1. Domestic situation:

1.1 In the 1970s and before, welding was carried out by traditional manual welding methods in pipeline construction. This welding method is no longer suitable for pipeline construction due to slow welding speed and low welding quality.

1.2 In the early 1980s, the Pipeline Bureau introduced the manual down welding process of the United States and Europe, and gradually extended it to most construction companies, and the quality has reached a new level. At that time, the quality of the meter was extended according to the weld, and the pass rate of x-ray was over 95%. This welding method has replaced the traditional manual welding method.

1.3 Self-protecting semi-automatic welding consumables mainly rely on imports. Since the pipeline bureau began experimenting in 1994, it has not achieved results. It is understood that several welding consumables research institutes have been developed in China, and no official products have been seen so far. No products have been seen at all welding exhibitions.

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1.4 The advantages of automatic welding technology are reflected in:

First, the quality of the pipe groove and the counterpart is high, that is, the pipe is required to be evenly distributed throughout the week;

Second, the groove type is strict. When the wall thickness of the pipe wall is thick, the composite type or U-shaped groove is used to determine the process. It is not only necessary to reduce the workload. More importantly, the weld quality of the groove is considered. Although the small angle V-shaped groove simplifies the construction procedure, the composite slope L or U-shaped groove is better from the perspective of quality assurance;

Third, it is greatly affected by the external climate, which is also a common problem of gas shielded welding;

Fourth, the problem of gas source in remote areas, especially argon gas, such as the west of the West-East Gas Pipeline Project, is suitable for automatic welding, but the argon gas source is far away, and the mixed gas is only close to Xi'an, which invisibly increases the engineering cost.

Through analysis, the best matching of automatic welding should be said to be the external welding of copper pad root welding and forced automatic welding, because the equipment is simple, easy to ensure internal molding, there are tests to prove that copper infiltration is conditional, the process is appropriate, It is completely possible to avoid copper infiltration or to cause harmful results.

According to the above analysis and the application of various welding methods, I personally believe that under normal circumstances, long-distance pipeline welding should be based on self-protection semi-automatic welding. Pipeline projects like the West-East Gas Pipeline should be promoted and applied in flat areas. The manual traditional welding method and the manual down welding method are supplemented. When the conditions permit, partial double tube welding can be used.

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