Precautions for welding stainless steel flanges

1. Stainless steel flange fittings have high hardenability after welding and are easy to crack. If the same type of stainless steel electrode (g202, G207) is used for welding, preheating above 300°C and slow cooling at about 700°C must be carried out after welding. If the weldment cannot be heat treated after welding, stainless steel flanged pipe electrodes (A107, A207) should be selected.

2. In order to prevent interocular corrosion of the stainless steel flange cover caused by heat, the welding current should not be too large, which is about 20% smaller than that of carbon steel electrodes, the arc should not be too long, the cooling between layers should be fast, and narrow weld bead should be used.

3. In order to improve the corrosion resistance and weldability of stainless steel flanges, an appropriate amount of stable elements Ti, Nb, Mo, etc. should be added appropriately. When the same type of stainless steel flange electrode (G302, G307) is used, preheating treatment above 200°C and tempering treatment at about 800°C should be carried out after welding. If the weldment cannot be heat treated, stainless steel flanged pipe electrodes (A107, A207) should be selected.

4. During the welding process of the stainless steel flange pipe, due to repeated heating, carbides are precipitated, which reduces the corrosion resistance and mechanical properties.