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The welding process is directly related to the quality of the welded pipe, and the welding quality of the 316L antibacterial stainless steel pipe is related to the welding method, welding materials, welding parameters, etc. Today we will talk about the welding process requirements of 316L antibacterial stainless steel pipe.
1. Welding method
According to the characteristics of antibacterial stainless steel, the heat input is reduced as much as possible, so two methods of manual arc welding and argon arc welding are used. When the diameter is greater than 159mm, argon arc welding is used to make the bottom, and manual arc welding is used for the cover; when the diameter is less than 159mm, argon arc welding is used. The welding machine adopts manual arc welding/argon arc welding dual-purpose WS7-400 inverter arc welding machine.
2. Welding materials
316L antibacterial stainless steel pipe is the steel for a special performance. In order to meet the same performance of the joint, the welding material should be selected according to the principle of "equal composition". At the same time, in order to enhance the ability of the joint to resist thermal cracks and intergranular corrosion, so that a small amount of body appears in the joint, the welding wire for argon arc welding of HooCr19Ni12Mo2 is selected. Electrode CHS022 is used as filler material for manual arc welding.
3. Welding parameters
The outstanding feature of the austenitic antibacterial stainless steel welded pipe is that it is sensitive to overheating, so low current and fast welding are used. During multi-layer welding, the interlayer temperature must be strictly controlled to make the interlayer temperature less than 60°C.
4. Groove form and assembly positioning welding
The groove form adopts a V-shaped groove. Due to the use of a smaller welding current, the depth of penetration is small. Therefore, the blunt edge of the groove is smaller than that of carbon steel, about 0-0.5mm, and the angle of the groove is larger than that of carbon steel, about 65-70 degrees. Because the thermal expansion coefficient of 316L antibacterial stainless steel pipe is relatively large, large welding stress is generated during welding, and strict positioning welding is required. Two-point positioning is used for pipes with a diameter of less than 89mm. Three-point positioning is adopted for diameters ranging from 89mm to 219mm. For diameters greater than 219mm, use four-point positioning, and the length of the positioning weld is 6-8mm.
Five, welding technical requirements
1. When manual arc welding is used, DC reverse connection should be used for welding; if it is argon arc welding, DC positive connection should be used.
2. Before the welding wire is used, the welding rod should be dried according to the requirements to prevent the generation of pores.
3. The surface of the groove and the weldment to be welded on each side of 20mm should be cleaned. There should be no oil, paint, scale, or other impurities. If necessary, clean with alcohol or acetone, or even grind. Otherwise, the weld metal will develop porosity and carburization.
4. When back welding 316L stainless steel pipes, the thickness of the weld seam should be uniform and well fused with the root. A gentle slope should be formed when the arc is closed, and the arc crater should be filled when the arc is extinguished to prevent arc craters. crack.
5. Welding should be carried out in sections, and cooling should be carried out after welding, which can be water-cooled, which can not only increase the cooling speed of the joint but also reduce the welding stress, which can be said to kill two birds with one stone.
The above is the welding process requirements of 316L antibacterial stainless steel pipe. From the above introduction, it can be known that 316L antibacterial stainless steel pipe welding can be performed by manual arc welding and argon arc welding; HooCr19Ni12Mo2 is selected as the welding wire for argon arc welding, and CHS022 is used as the filling material for manual arc welding; the interlayer temperature during multilayer welding is less than 60°C; the groove is a V-shaped groove, the blunt edge of the groove is about 0-0.5mm, and the groove angle is 65°-70°; in addition, there are some 316L antibacterial stainless steel pipe welding technology requirements that need attention.
Dingshang Stainless Steel Co., Ltd. is a China duplex stainless steel welded pipes supplier. It specializes in wholesale and sales of stainless steel pipes/tubes. Welcome to consult.