The use of stainless steel flange should pay attention to what aspects

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2023-06-13 10:02

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Stainless steel flanges are flanges that extend steel pipes, pipe fittings, etc. into the flanges and are connected to equipment or pipelines through fillet welds. The inner hole on one side of the flange is provided with a welding boss, and the welding boss is provided with an inner hole. The inner hole communicates with 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 the welding boss. There are many screw holes on the flange. The screw holes are symmetrically distributed around the center of the flange. The stainless steel flange is made of stainless steel, followed by a polyethylene plastic layer, a rubber layer and a PVC layer. Here we take a look at the use of stainless steel flange precautions.

1. In order to prevent corrosion between eyes caused by heating of stainless steel flanges, the welding current should not be too large, about 20% less than carbon steel electrode, the arc should not be too long, the cooling speed is between the number of layers, and the narrow bead effect is better.

2. The electrode should be kept dry during use. Perovskite type needs to be dried at 150 ℃ for 1 hour, and low hydrogen type needs to be dried at 200-250 ℃ for 1 hour (do not repeat drying many times, otherwise the coating is easy to crack and peel off) to prevent the welding rod coating from sticking oil and other pollution, 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, repeated heating will precipitate carbides, reducing corrosion resistance and mechanical properties.

4. The American standard flange with large hardenability after welding of chromium stainless steel flange pipe fittings is prone to cracks. If the same chromium stainless steel electrode is used for welding, it shall be preheated above 300 ℃ and slowly cooled at about 700 ℃ after welding. If the weldment cannot be post-weld heat treated, stainless steel flanged pipe electrodes shall be used.

5. For stainless steel flanges, add appropriate amount of stabilizing elements Ti, Nb, Mo, etc. to improve corrosion resistance and weldability. Weldability is better than chrome stainless steel flanges. When using the same type of chromium stainless steel flange welding rod, it should be preheated above 200 ℃ and tempered at about 800 ℃ after welding. If the weldment cannot be heat treated, a stainless steel flanged pipe electrode should be used.

6. Stainless steel flange pipe fittings and butt welding flange electrodes have good corrosion resistance and oxidation resistance, and are widely used in chemical, fertilizer, petroleum, and medical machinery manufacturing.

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Advantages and disadvantages of flat welding flange

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Flat welded flanges are mainly used for gas valves and natural gas pipelines. Because the short neck can improve the rigidity and carrying capacity of the flange. Flat welded flanges are used for general media. Flat welding flange with neck is suitable for flammable, explosive, corrosive and toxic places. The sealing surface of flat welding flange can be convex surface, concave convex surface and tongue and groove surface. They are different in structure, sealing effect and strength. Flat welding flange is generally called flat plate, also known as lap welding flange. The connection between the flat welding flange and the pipe is to insert the pipe into the flange inner hole to the appropriate position before the lap welding. The characteristics of flat welding flange: flat welding flange not only saves space, reduces weight, but also ensures no leakage at the joint and good sealing performance. The reason for the reduced size of the compact flange is the reduced diameter of the seal, which will reduce the cross section of the sealing surface. The advantages of flat welding flanges are as follows:

Applicable scope and purpose of welding flange

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