1. To prevent intergranular corrosion caused by heating of the flange cover, the welding current should not be too high, about 20% less than that of carbon steel welding rods. The arc should not be too long, and the interlayer should be cooled quickly. Narrow weld beads are preferred.
2. Welding rods should be kept dry during use. Titanium calcium type should be dried at 150 ℃ for 1 hour, and low alpha hydrogen type should be dried at 200-250 ℃ for 1 hour (repeated drying is not allowed, otherwise the coating is prone to cracking and peeling), to prevent the coating of the welding rod from sticking oil and other dirt, so as not to increase the carbon content of the weld and affect the quality of the welded part.
3. When welding stainless steel flange fittings, repeated heating can precipitate carbides, reducing their corrosion resistance and mechanical properties.
4. Chromium stainless steel flange fittings have a relatively large hardening after welding, and are prone to cracking. If the same type of chromium stainless steel welding rod (G202, G207) is used for welding, preheating at 300 ℃ or above and slow cooling treatment at around 700 ℃ after welding must be carried out. If the welded parts cannot undergo post weld heat treatment, stainless steel flange fittings welding rods (A107, A207) should be selected.
5. Stainless steel flanges, with the appropriate addition of stabilizing elements such as Ti, Nb, Mo to improve corrosion resistance and weldability, have better weldability than chromium stainless steel flanges. When using the same type of chromium stainless steel flange welding rods (G302, G307), preheating at 200 ℃ or above and tempering treatment at around 800 ℃ after welding should be carried out. If the welded parts cannot undergo heat treatment, stainless steel flange fittings welding rods (A107, A207) should be selected.
6. Stainless steel flange fittings and butt welded flange welding rods have good corrosion resistance and oxidation resistance, and are widely used in the manufacturing of chemical, fertilizer, petroleum, and medical machinery.
