The stainless steel welded pipe is obtained by reacting a molten metal with an iron matrix to produce an alloy layer, thereby combining the substrate and the plating layer. Hot-dip galvanizing is to pickle the steel pipe first, in order to remove the iron oxide on the surface of the steel pipe, after pickling, it is washed by ammonium chloride or zinc chloride aqueous solution or a mixed aqueous solution of ammonium chloride and zinc chloride, and then fed. Hot dip plating tank. Hot-dip galvanizing has the advantages of uniform plating, strong adhesion and long service life.
In the welding quality standard of stainless steel pipe fittings, the single welding of double-sided welding or padding is not allowed to exist in the final welding penetration defect. For single-sided welding without padding, the permissible penetration defects are related to the importance of the weld. Important welds are not allowed to be single-passed; the more important welds are allowed to have a final penetration depth not exceeding 10% to 15% of the thickness of the base metal and not exceeding 2M. The length of the incomplete penetration does not exceed the weld of the same grade. The total length of the slag allowed; generally, the penetration depth at the end of the weld shall be less than 20% of the thickness of the base metal, and shall not exceed 3 mm, and the length shall be less than the total length of the permitted hem. To control the groove size of the stainless steel pipe joints, thoroughly clean the roots and select the appropriate welding current and welding speed. For example, a single-sided welded double-sided butt joint has a set pair gap which is generally equal to the diameter of the electrode, and the blunt edge height is about 1/2 of the diameter of the electrode.
Stainless steel welded pipe use precautions
1. A power supply with a vertical external characteristic is generally used, and a positive polarity is used for a direct current.
2. It is generally suitable for the welding of thin plates of 6mm or less, and has the characteristics of beautiful weld bead formation and small welding deformation.
3. The shielding gas is argon with a purity of 99.99%. When the welding current is 50~50A, the argon flow rate is 8~0L/min. When the current is 50~250A, the argon flow rate is 2~5L/min.
4. The length of the tungsten electrode protruding from the gas nozzle is preferably 4~5mm, 2~3mm in the place with poor shielding such as fillet welding, 5~6mm in the deep groove, and the distance from the nozzle to the work is generally not more than 5mm.
5. In order to prevent the occurrence of welding vents, the welding parts must be cleaned such as rust and oil.
6. Welding arc length, when welding ordinary steel, it is better to use 2~4mm, while when welding stainless steel, it is better to use ~3mm. If it is too long, the protection effect is not good.
7. When the bottom of the butt weld is prevented from being oxidized, the back side also needs to be protected by gas.
8. In order to make the argon gas protect the weld pool well and facilitate the welding operation, the tungsten center line and the welding workpiece should generally maintain an angle of 80~85°, and the angle between the filler wire and the workpiece surface should be as small as possible. Usually about 0 °.
9. Wind and ventilation. In windy places, take measures to block the net, and indoors should take appropriate ventilation measures.