Manual arc welding includes the application of cellulose electrodes and low hydrogen electrodes. The manual arc welding up welding technology is the main welding method in the past pipeline construction in China. It is characterized by large gaps in the nozzle group and the use of the arc operation method in the welding process. The thickness of each layer is large and the welding efficiency is low. . Manual arc welding down welding is a welding technology introduced from abroad in the 1980s. It is characterized by small gaps in the nozzle group, high current, multi-layer and fast welding operation methods in the welding process. It is suitable for flow operation and welding. More efficient. Since the thickness of each layer of the solder layer is thin, the heat treatment of the front solder layer by the back solder layer can improve the toughness of the ring solder joint. The manual arc welding method is flexible, simple and adaptable. The organic combination of the two methods of down welding and up welding and the good root welding adaptability of the cellulose electrode are still not replaced by the automatic welding method in many occasions. Self-shielded flux-cored wire semi-automatic welding technology was applied to pipeline construction in the 1990s, mainly for filling and covering. The utility model has the advantages that the welding efficiency is high, the whole position is formed well, the environment adaptability is strong, and the welder is easy to grasp, which is an important welding process method of the pipeline construction at present.
With the increase of the strength grade of the steel pipe for pipeline construction, the increase of the pipe diameter and the wall thickness, the automatic welding technology is gradually applied in the pipeline construction. Pipeline automatic welding technology has great potential in the application of large-diameter and thick-walled pipelines due to its high welding efficiency, low labor intensity, and small impact of the welding process by human factors. However, China's pipeline automatic welding technology is in its infancy, the root automatic welding problem has not been solved, and the supporting equipment such as the pipe end beveling machine is not yet mature, which limits the large-scale application of automatic welding technology. At present, automatic root welding mainly adopts the development trend of high pressure and ultra high pressure natural gas pipeline welding technology.
The development of the oil and gas and petrochemical industries is marked by the West-East Gas Pipeline Project. The peak period of China's long-distance pipeline construction has arrived. Long-distance oil and gas pipelines are increasingly developing in the direction of large-diameter and high-pressure transmission. Since the introduction of the long-distance pipeline down-welding technology into China since the 1960s, after decades of development, it has mature manual down-welding technology and is popularizing semi-automatic gas shielded welding technology. The combination of fully automatic gas shielded welding technology and down welding technology as the development trend of high pressure pipeline welding technology will be vigorously promoted in the construction of long-distance pipelines nationwide. Due to the successful application of the manual down-welding technology and the semi-automatic welding process of self-shielded flux-cored wire in the "West-East Gas Transmission" Shanghai I-VI section project, there are relatively complete construction work specifications, so this article is no longer Narration. For STT technology semi-automatic gas shielded welding and fully automatic gas shielded welding, there is no engineering practice or welding test in the gas pipelines in Shanghai. Therefore, the paper discusses these two welding processes in detail, and undertakes the future high-pressure gas for the Shanghai area. Pipeline engineering provides technical reference.
STT technology CO 2 gas protection semi-automatic down-welding technology STT-type CO 2 semi-automatic welding is the root welding of pipelines by STT welding technology. The shielding gas for root welding is CO 2 . A hand-welded welding process for automatic wire feeding using a flux-cored wire (such as Lincoln's NR207). STT is the abbreviation of “Surface Tension Transferâ€, meaning that the surface tension is excessive, which is a transition mechanism of welded deposited metal. (The filling surface welding using this process is similar to the semi-automatic welding filling surface technology adopted by our company. This article is no longer developed. The main description is the STT root welding technology. Process characteristics: STT welding in the welding of pressure pipes is An inexpensive and efficient welding method. Traditional CO2 gas shielded welding can not fundamentally solve the problem of large welding spatter and unsatisfactory weld formation. The STT type CO 2 semi-automatic welding machine with waveform control technology ensures the welding process. Stable, the weld is beautifully formed, the effect of dry elongation change is small, the splash is significantly reduced, and the labor intensity of the welder is reduced.
Galvanized Steel Coil immerse thin steel plate in the molten zinc groove, so that its surface adheres to a thin sheet of zinc. At present, galvanized steel coil is mainly made of continuous galvanizing process, that is, the rolled steel plate is continuously dipped into galvanized steel plate in the molten zinc plating bath, and the galvanized steel sheet is alloyed. The steel plate is also made by hot dipping, but immediately after the trough, it is heated to about 500 ℃to make the alloy film of zinc and iron. The galvanized steel coil has a good tightness and weldability of the coating.
Description of the galvanized steel coil:
Grade: Q235 Q345
Width: 600-1500mm
Thickness: 0.13-0.8mm
Zinc coat: 30-275g/m2
Length: According to your requirement
Package: Kraft paper is inside, outside is iron sheet; or according to your requirement
MOQ: 5tons except the coil with special zinc coat
Payment: T/T; L/C; Western union
Delivery: Shipped with in 10-30 days after we get your deposit.
FAQ:
1.Is free sample available?
Yes, free sample is available.
2. Does the packaging safe and arrive in good conditions?
Yes, safe packing guarantee , all the products will arrive your door under good conditions.
3. How do you ensure quality control?
we ensure the quality control by 2 steps:
1)after finish, our workers will check it one by one.
2)our package department will check before they pack.
Galvanized Steel Coil
Galvanized Steel Coil,Electro Galvanized Steel Coils,Prepainted Galvanized Steel Coil,Color Coating Galvanized Steel Coil
Shijiazhuang Zhouming Steel Building Materials Co., Ltd. , http://www.zmsteels.com