In order to prevent the inter eye corrosion caused by the heating of non-standard flange cover, the welding current should not be too large, the amount of carbon steel electrode should not be less than 20%, the arc should not be too long, the interlayer cooling speed should be fast, and the narrow hole weld bead is the best.
When in use, the electrode should be kept dry, the titanium calcium electrode should be dried at 150 ° C for 1h, and the low-a electrode should be dried at 200-250 ° C for 1H (do not dry repeatedly, otherwise the electrode coating is easy to crack and peel off), so as to prevent the electrode coating from adhering to oil and other dirt, do not increase the carbon content of the weld, and affect the quality of the weldment.
Non standard flange pipe welding, after repeated heating, produces carbides, which reduces corrosion resistance and mechanical properties.
After welding and hardening of non-standard flange pipe fittings, the American standard flange is large and prone to cracks. If the same type of chromium stainless steel electrode (g202, G207) is used for welding, it must undergo preheating of more than 300 ° C and slow cooling treatment of about 700 ° C after welding. If the welded parts cannot be heat treated after welding, stainless steel non-standard flange pipe welding rods (A107, A207) should be selected.
For non-standard flanges, in order to improve corrosion resistance and weldability, titanium, niobium, molybdenum and other stable elements are appropriately added, and the weldability is better than that of chromium stainless steel non-standard flanges. Chromium stainless steel non-standard flange electrodes (G302, G307) of the same type shall be preheated to more than 200 ° C and tempered at 800 ° C after welding. If the welding part cannot be heat treated, stainless steel non-standard flange pipe welding rods (A107, A207) should be selected.