Precautions for use of plate flange
2021-09-23 14:21:04 COMMENT：0 HITS：
1. In order to prevent the eye corrosion caused by the heating of the plate flange cover, the welding current should not be too large, about 20% less than the carbon steel electrode, the arc should not be too long, and the interlayer should be cooled quickly, and the narrow weld bead is preferred.
2. The electrode shall be kept dry during use. The titanium calcium type shall be dried at 150 ℃ for 1 hour, and the low a hydrogen type shall be dried at 200-250 ℃ for 1 hour (repeated drying is not allowed, otherwise the coating is easy to crack and peel off), so as to prevent oil and other dirt on the electrode coating, so as not to increase the carbon content of the weld and affect the quality of the weldment.
3. When stainless steel flange pipe fittings are welded, carbides are precipitated by repeated heating, which reduces corrosion resistance and mechanical properties.
4. Chromium stainless steel flange pipe fittings have large hardenability after welding, and American standard flange is easy to crack. If the same type of chromium stainless steel electrodes (g202 and G207) are used for welding, preheating above 300 ℃ and slow cooling treatment at about 700 ℃ after welding must be carried out. If the weldment cannot be subject to post weld heat treatment, stainless steel flange pipe fittings welding rods (A107, A207) shall be selected.
5. Stainless steel flange, in order to improve corrosion resistance and weldability, appropriate amount of stability elements Ti, Nb, Mo, etc. are added, and the weldability is better than that of chromium stainless steel flange. When the same type of chromium stainless steel flange electrode (G302, G307) is used, it shall be preheated above 200 ℃ and tempered at about 800 ℃ after welding. If the weldment cannot be heat treated, stainless steel flange pipe fittings welding rods (A107, A207) shall be selected.
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