There are three welding processes for the Straight seam steel pipe, namely submerged arc welding, high-frequency welding, and resistance welding. Double-sided submerged arc welding is adopted for a diameter above 406mm, and high-frequency welding or resistance welding is adopted for a diameter below 406mm. The process of submerged arc welding with too small caliber cannot carry out flow production, because the steel plate is difficult to press, and it is also difficult to weld, so only for the large straight seam steel pipe, high frequency and resistance welding corresponding to the large caliber of the first step of thick plate pressing can not be done, and even the thickness of more than 14mm can not meet the requirements. The production process of the three welding processes also has differences.

The main welding process and flow of submerged arc welding are as follows. Submerged arc welding (including submerged arc surfacing and ESG surfacing, etc.) is a welding method in which the arc is burned under the flux layer. Its inherent advantages of stable welding, welding, no arc light, and little smoke make it become the main welding method in the manufacture of pressure vessels, pipe sections, box beams and columns, and other important steel structures. The welding process is automatically controlled by operating the button switch on the control panel. In the welding process, the workpiece is covered with a layer of 30-50mm thick granular flux. The continuous wire is sent to produce an arc between the welding parts and the flux layer. The heat of the arc makes the wire, the workpiece, and the flux melt, forming a metal melt pool so that they are isolated from the air. With the automatic forward movement of the welding machine, the arc continues to melt the welding metal in front of the welding wire and flux, and the edge of the rear of the molten pool began to cool and solidified to form a weld, liquid molten slag then condensed to form a hard slag shell for bridge piling, Marine wharf piling, steel support, pipeline and so on some construction projects, submerged arc welding also has a common name LSAW.

The welding process of high frequency and resistance is relatively simple because the projects using high-frequency welding are some low-pressure fluid pipelines, such as water pipes, sewage pipes, small vents, drinking water pipes, and so on. High-frequency welding refers to the use of high-frequency current, through the workpiece contact surface generated resistance to heat, and application pressure (or no pressure), so that the workpiece metal forms a connection welding method. High-frequency welding is different from resistance welding. In high-frequency welding, the welding current is only in parallel contact with the workpiece surface. The current flow of resistance welding is perpendicular to the welding interface. In general, the frequency of high-frequency welding is selected in 300 ~ 450kHz: resistance welding is the use of 50kHz power frequency electricity.

There are also differences in the prices of different production welding processes. The price of submerged arc welding large-diameter straight seam steel pipe is 4320 yuan per ton, and the price of high-frequency welding small-diameter thin-wall straight seam steel pipe is about 4180 yuan. This can not be said to be the difference in welding process, but only the difference between small-diameter straight-seam steel pipe and large-diameter straight-seam steel pipe.

Cangzhou Shenlong Pipe mainly produces seamless steel pipe, straight seam steel pipe, spiral steel pipe, but also can process galvanized, anti-corrosion coating, has more than 20 years of production history, reliable quality, and is a qualified supplier of BP oil, PetroChina.