Precautions for the operation of flat welding flanges:
1. In order to prevent the corrosion between the eyes due to the heating of the flange cover, the welding current should not be too large, less than about 20% than the carbon steel electrode, the arc should not be too long, the interlayer cooling is fast, and the narrow welding bead is better.
2. The electrode should be kept dry when using it. The titanium calcium type should be kept at 150℃ for 1 hour, and the low-a hydrogen type should be kept at 200-250℃ for 1 hour to prevent the electrode coating from sticking to oil and other dirt, so as not to cause the weld. Increase the carbon content and affect the quality of weldments.
3. When flat-welded flange pipe fittings are welded, they are repeatedly heated to precipitate carbides, which reduces the corrosion resistance and mechanical properties of the product.
4. After welding, the hardenability of chrome flat welded flange pipe fittings is larger and the American standard flange is prone to cracks. If the same type of chromium stainless steel electrode (G202, G207) is used for welding, preheating above 300°C and slow cooling treatment at about 700°C after welding must be carried out. If the weldment cannot be subjected to post-weld heat treatment, flat welding flange pipe welding rods (A107, A207) should be used.
5. Flat-welded flanges, in order to improve the corrosion resistance and weldability, appropriate amount of stability elements Ti, Nb, Mo, etc. are added appropriately, and the weldability is better than that of chrome flat-welded flanges. When using the same type of chrome flat welding flange electrode (G302, G307), preheating above 200°C and tempering treatment at about 800°C after welding should be carried out. If the weldment cannot be heat treated, flat welding flange pipe welding rods (A107, A207) should be used.
The main function of flat welding flange:
1. Connect the pipeline and maintain the sealing performance of the pipeline;
2. Facilitate the replacement of a certain section of pipeline;
3. It is easy to disassemble and check the pipeline condition;
4. Facilitate the closure of a certain section of pipeline.