Stainless steel flange is a flange that extends steel pipes, pipe fittings, etc. into the flange and connects it to equipment or pipelines through fillet welds. The inner hole on one side of the flange is equipped with a welding boss, and the welding boss is equipped with an inner hole. The inner hole is connected to the inner hole in the center of the flange, and there is elasticity between the flange and the welding boss. The two top surfaces of the elastic ring are respectively combined with the flange and welding boss. There are many screw holes on the flange. The screw holes are symmetrically distributed around the center of the flange. Stainless steel flanges are made of stainless steel, followed by polyethylene plastic layer, rubber layer, and PVC layer. Let's take a look at the precautions for using stainless steel flanges.
1. To prevent eye to eye corrosion caused by heating of stainless steel flanges, the welding current should not be too large, which is about 20% less than carbon steel welding rods. The arc should not be too long, and the cooling speed should be between the layers. Narrow welding beads have better effects.
2. The electrode should be kept dry during use. The perovskite type needs to be dried at 150 ℃ for 1 hour, while the low hydrogen type needs to be dried at 200-250 ℃ for 1 hour (do not repeat drying multiple times, otherwise the coating may crack and peel off) to prevent contamination such as oil stains on the electrode coating, and to avoid increasing the carbon content of the weld and affecting the quality of the weld.
3. When welding stainless steel flange fittings, repeated heating can precipitate carbides, reducing corrosion resistance and mechanical properties.
4. American standard flanges with high hardenability after welding of chrome stainless steel flange fittings are prone to cracking. If the same type of chromium stainless steel welding rod is used for welding, it needs to be preheated at 300 ℃ or above after welding and slowly cooled at around 700 ℃. If the weldment cannot undergo post weld heat treatment, stainless steel flange pipe welding rods should be used.
5. For stainless steel flanges, add an appropriate amount of stable elements such as Ti, Nb, Mo, etc. to improve corrosion resistance and weldability. The weldability is better than that of chrome stainless steel flanges. When using chromium stainless steel flange welding rods of the same model, preheating should be above 200 ℃ and tempering should be around 800 ℃ after welding. If the weldment cannot undergo heat treatment, stainless steel flange pipe welding rods should be used.
6. Stainless steel flange fittings and welding flange electrodes have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.